[PATCH 0/4] Invalidate secondary IOMMU TLB on permission upgrade

[PATCH 0/4] Invalidate secondary IOMMU TLB on permission upgrade

[Alistair Popple]

The main change is to move secondary TLB invalidation mmu notifier
callbacks into the architecture specific TLB flushing functions. This
makes secondary TLB invalidation mostly match CPU invalidation while
still allowing efficient range based invalidations based on the
existing TLB batching code.

==========
Background
==========

The arm64 architecture specifies TLB permission bits may be cached and
therefore the TLB must be invalidated during permission upgrades. For
the CPU this currently occurs in the architecture specific
ptep_set_access_flags() routine.

Secondary TLBs such as implemented by the SMMU IOMMU match the CPU
architecture specification and may also cache permission bits and
require the same TLB invalidations. This may be achieved in one of two
ways.

Some SMMU implementations implement broadcast TLB maintenance
(BTM). This snoops CPU TLB invalidates and will invalidate any
secondary TLB at the same time as the CPU. However implementations are
not required to implement BTM.

Implementations without BTM rely on mmu notifier callbacks to send
explicit TLB invalidation commands to invalidate SMMU TLB. Therefore
either generic kernel code or architecture specific code needs to call
the mmu notifier on permission upgrade.

Currently that doesn't happen so devices will fault indefinitely when
writing to a PTE that was previously read-only as nothing invalidates
the SMMU TLB.

========
Solution
========

To fix this the series first renames the .invalidate_range() callback
to .arch_invalidate_secondary_tlbs() as suggested by Jason and Sean to
make it clear this callback is only used for secondary TLBs. That was
made possible thanks to Sean's series [1] to remove KVM's incorrect
usage.

Based on feedback from Jason [2] the proposed solution to the bug is
to move the calls to mmu_notifier_arch_invalidate_secondary_tlbs()
closer to the architecture specific TLB invalidation code. This
ensures the secondary TLB won't miss invalidations, including the
existing invalidation in the ARM64 code to deal with permission
upgrade.

Currently only ARM64, PowerPC and x86 have IOMMU with secondary TLBs
requiring SW invalidation so the notifier is only called for those
architectures. It is also not called for invalidation of kernel
mappings as no secondary IOMMU implementations can access those and
hence it is not required.

[1] - https://lore.kernel.org/all/20230602011518.787006-1-seanjc@google.com/
[2] - https://lore.kernel.org/linux-mm/ZJMR5bw8l+BbzdJ7@ziepe.ca/

Alistair Popple (4):
  mm_notifiers: Rename invalidate_range notifier
  arm64/smmu: Use TLBI ASID when invalidating entire range
  mmu_notifiers: Call arch_invalidate_secondary_tlbs() when invalidating TLBs
  mmu_notifiers: Don't invalidate secondary TLBs as part of mmu_notifier_invalidate_range_end()

 arch/arm64/include/asm/tlbflush.h               |   5 +-
 arch/powerpc/include/asm/book3s/64/tlbflush.h   |   1 +-
 arch/powerpc/mm/book3s64/radix_hugetlbpage.c    |   1 +-
 arch/powerpc/mm/book3s64/radix_tlb.c            |   6 +-
 arch/x86/mm/tlb.c                               |   3 +-
 drivers/iommu/amd/iommu_v2.c                    |  10 +-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c |  29 +++--
 drivers/iommu/intel/svm.c                       |   8 +-
 drivers/misc/ocxl/link.c                        |   8 +-
 include/asm-generic/tlb.h                       |   1 +-
 include/linux/mmu_notifier.h                    | 104 ++++-------------
 kernel/events/uprobes.c                         |   2 +-
 mm/huge_memory.c                                |  29 +----
 mm/hugetlb.c                                    |   8 +-
 mm/memory.c                                     |   8 +-
 mm/migrate_device.c                             |   9 +-
 mm/mmu_notifier.c                               |  47 +++-----
 mm/rmap.c                                       |  40 +-------
 18 files changed, 109 insertions(+), 210 deletions(-)

base-commit: fdf0eaf11452d72945af31804e2a1048ee1b574c
-- 
git-series 0.9.1

[PATCH 1/4] mm_notifiers: Rename invalidate_range notifier

[Alistair Popple]

There are two main use cases for mmu notifiers. One is by KVM which
uses mmu_notifier_invalidate_range_start()/end() to manage a software
TLB.

The other is to manage hardware TLBs which need to use the
invalidate_range() callback because HW can establish new TLB entries
at any time. Hence using start/end() can lead to memory corruption as
these callbacks happen too soon/late during page unmap.

mmu notifier users should therefore either use the start()/end()
callbacks or the invalidate_range() callbacks. To make this usage
clearer rename the invalidate_range() callback to
arch_invalidate_secondary_tlbs() and update documention.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
---
 arch/x86/mm/tlb.c                               |  1 +-
 drivers/iommu/amd/iommu_v2.c                    | 10 +--
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 13 ++--
 drivers/iommu/intel/svm.c                       |  8 +--
 drivers/misc/ocxl/link.c                        |  8 +--
 include/asm-generic/tlb.h                       |  2 +-
 include/linux/mmu_notifier.h                    | 54 +++++++++---------
 mm/huge_memory.c                                |  4 +-
 mm/hugetlb.c                                    | 10 +--
 mm/mmu_notifier.c                               | 52 ++++++++++-------
 mm/rmap.c                                       | 42 +++++++-------
 11 files changed, 110 insertions(+), 94 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 267acf2..eaefc10 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -10,6 +10,7 @@
 #include <linux/debugfs.h>
 #include <linux/sched/smt.h>
 #include <linux/task_work.h>
+#include <linux/mmu_notifier.h>
 
 #include <asm/tlbflush.h>
 #include <asm/mmu_context.h>
diff --git a/drivers/iommu/amd/iommu_v2.c b/drivers/iommu/amd/iommu_v2.c
index 261352a..2596466 100644
--- a/drivers/iommu/amd/iommu_v2.c
+++ b/drivers/iommu/amd/iommu_v2.c
@@ -355,9 +355,9 @@ static struct pasid_state *mn_to_state(struct mmu_notifier *mn)
 	return container_of(mn, struct pasid_state, mn);
 }
 
-static void mn_invalidate_range(struct mmu_notifier *mn,
-				struct mm_struct *mm,
-				unsigned long start, unsigned long end)
+static void mn_arch_invalidate_secondary_tlbs(struct mmu_notifier *mn,
+					struct mm_struct *mm,
+					unsigned long start, unsigned long end)
 {
 	struct pasid_state *pasid_state;
 	struct device_state *dev_state;
@@ -391,8 +391,8 @@ static void mn_release(struct mmu_notifier *mn, struct mm_struct *mm)
 }
 
 static const struct mmu_notifier_ops iommu_mn = {
-	.release		= mn_release,
-	.invalidate_range       = mn_invalidate_range,
+	.release			= mn_release,
+	.arch_invalidate_secondary_tlbs	= mn_arch_invalidate_secondary_tlbs,
 };
 
 static void set_pri_tag_status(struct pasid_state *pasid_state,
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
index a5a63b1..aa63cff 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
@@ -186,9 +186,10 @@ static void arm_smmu_free_shared_cd(struct arm_smmu_ctx_desc *cd)
 	}
 }
 
-static void arm_smmu_mm_invalidate_range(struct mmu_notifier *mn,
-					 struct mm_struct *mm,
-					 unsigned long start, unsigned long end)
+static void arm_smmu_mm_arch_invalidate_secondary_tlbs(struct mmu_notifier *mn,
+						struct mm_struct *mm,
+						unsigned long start,
+						unsigned long end)
 {
 	struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn);
 	struct arm_smmu_domain *smmu_domain = smmu_mn->domain;
@@ -237,9 +238,9 @@ static void arm_smmu_mmu_notifier_free(struct mmu_notifier *mn)
 }
 
 static const struct mmu_notifier_ops arm_smmu_mmu_notifier_ops = {
-	.invalidate_range	= arm_smmu_mm_invalidate_range,
-	.release		= arm_smmu_mm_release,
-	.free_notifier		= arm_smmu_mmu_notifier_free,
+	.arch_invalidate_secondary_tlbs	= arm_smmu_mm_arch_invalidate_secondary_tlbs,
+	.release			= arm_smmu_mm_release,
+	.free_notifier			= arm_smmu_mmu_notifier_free,
 };
 
 /* Allocate or get existing MMU notifier for this {domain, mm} pair */
diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index e95b339..8f6d680 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -219,9 +219,9 @@ static void intel_flush_svm_range(struct intel_svm *svm, unsigned long address,
 }
 
 /* Pages have been freed at this point */
-static void intel_invalidate_range(struct mmu_notifier *mn,
-				   struct mm_struct *mm,
-				   unsigned long start, unsigned long end)
+static void intel_arch_invalidate_secondary_tlbs(struct mmu_notifier *mn,
+					struct mm_struct *mm,
+					unsigned long start, unsigned long end)
 {
 	struct intel_svm *svm = container_of(mn, struct intel_svm, notifier);
 
@@ -256,7 +256,7 @@ static void intel_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 
 static const struct mmu_notifier_ops intel_mmuops = {
 	.release = intel_mm_release,
-	.invalidate_range = intel_invalidate_range,
+	.arch_invalidate_secondary_tlbs = intel_arch_invalidate_secondary_tlbs,
 };
 
 static DEFINE_MUTEX(pasid_mutex);
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 4cf4c55..c06c699 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -491,9 +491,9 @@ void ocxl_link_release(struct pci_dev *dev, void *link_handle)
 }
 EXPORT_SYMBOL_GPL(ocxl_link_release);
 
-static void invalidate_range(struct mmu_notifier *mn,
-			     struct mm_struct *mm,
-			     unsigned long start, unsigned long end)
+static void arch_invalidate_secondary_tlbs(struct mmu_notifier *mn,
+					struct mm_struct *mm,
+					unsigned long start, unsigned long end)
 {
 	struct pe_data *pe_data = container_of(mn, struct pe_data, mmu_notifier);
 	struct ocxl_link *link = pe_data->link;
@@ -509,7 +509,7 @@ static void invalidate_range(struct mmu_notifier *mn,
 }
 
 static const struct mmu_notifier_ops ocxl_mmu_notifier_ops = {
-	.invalidate_range = invalidate_range,
+	.arch_invalidate_secondary_tlbs = arch_invalidate_secondary_tlbs,
 };
 
 static u64 calculate_cfg_state(bool kernel)
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index b466172..48c81b9 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -456,7 +456,7 @@ static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
 		return;
 
 	tlb_flush(tlb);
-	mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
+	mmu_notifier_invalidate_secondary_tlbs(tlb->mm, tlb->start, tlb->end);
 	__tlb_reset_range(tlb);
 }
 
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 64a3e05..a4bc818 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -187,27 +187,27 @@ struct mmu_notifier_ops {
 				     const struct mmu_notifier_range *range);
 
 	/*
-	 * invalidate_range() is either called between
-	 * invalidate_range_start() and invalidate_range_end() when the
-	 * VM has to free pages that where unmapped, but before the
-	 * pages are actually freed, or outside of _start()/_end() when
-	 * a (remote) TLB is necessary.
+	 * arch_invalidate_secondary_tlbs() is used to manage a non-CPU TLB
+	 * which shares page-tables with the CPU. The
+	 * invalidate_range_start()/end() callbacks should not be implemented as
+	 * invalidate_secondary_tlbs() already catches the points in time when
+	 * an external TLB needs to be flushed.
 	 *
-	 * If invalidate_range() is used to manage a non-CPU TLB with
-	 * shared page-tables, it not necessary to implement the
-	 * invalidate_range_start()/end() notifiers, as
-	 * invalidate_range() already catches the points in time when an
-	 * external TLB range needs to be flushed. For more in depth
-	 * discussion on this see Documentation/mm/mmu_notifier.rst
+	 * This requires arch_invalidate_secondary_tlbs() to be called while
+	 * holding the ptl spin-lock and therefore this callback is not allowed
+	 * to sleep.
 	 *
-	 * Note that this function might be called with just a sub-range
-	 * of what was passed to invalidate_range_start()/end(), if
-	 * called between those functions.
+	 * This is called by architecture code whenever invalidating a TLB
+	 * entry. It is assumed that any secondary TLB has the same rules for
+	 * when invalidations are required. If this is not the case architecture
+	 * code will need to call this explicitly when required for secondary
+	 * TLB invalidation.
 	 */
-	void (*invalidate_range)(struct mmu_notifier *subscription,
-				 struct mm_struct *mm,
-				 unsigned long start,
-				 unsigned long end);
+	void (*arch_invalidate_secondary_tlbs)(
+					struct mmu_notifier *subscription,
+					struct mm_struct *mm,
+					unsigned long start,
+					unsigned long end);
 
 	/*
 	 * These callbacks are used with the get/put interface to manage the
@@ -397,8 +397,8 @@ extern void __mmu_notifier_change_pte(struct mm_struct *mm,
 extern int __mmu_notifier_invalidate_range_start(struct mmu_notifier_range *r);
 extern void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *r,
 				  bool only_end);
-extern void __mmu_notifier_invalidate_range(struct mm_struct *mm,
-				  unsigned long start, unsigned long end);
+extern void __mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
+					unsigned long start, unsigned long end);
 extern bool
 mmu_notifier_range_update_to_read_only(const struct mmu_notifier_range *range);
 
@@ -491,11 +491,11 @@ mmu_notifier_invalidate_range_only_end(struct mmu_notifier_range *range)
 		__mmu_notifier_invalidate_range_end(range, true);
 }
 
-static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
-				  unsigned long start, unsigned long end)
+static inline void mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
+					unsigned long start, unsigned long end)
 {
 	if (mm_has_notifiers(mm))
-		__mmu_notifier_invalidate_range(mm, start, end);
+		__mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, end);
 }
 
 static inline void mmu_notifier_subscriptions_init(struct mm_struct *mm)
@@ -589,7 +589,7 @@ static inline void mmu_notifier_range_init_owner(
 	pte_t ___pte;							\
 									\
 	___pte = ptep_clear_flush(__vma, __address, __ptep);		\
-	mmu_notifier_invalidate_range(___mm, ___addr,			\
+	mmu_notifier_arch_invalidate_secondary_tlbs(___mm, ___addr,		\
 					___addr + PAGE_SIZE);		\
 									\
 	___pte;								\
@@ -602,7 +602,7 @@ static inline void mmu_notifier_range_init_owner(
 	pmd_t ___pmd;							\
 									\
 	___pmd = pmdp_huge_clear_flush(__vma, __haddr, __pmd);		\
-	mmu_notifier_invalidate_range(___mm, ___haddr,			\
+	mmu_notifier_arch_invalidate_secondary_tlbs(___mm, ___haddr,		\
 				      ___haddr + HPAGE_PMD_SIZE);	\
 									\
 	___pmd;								\
@@ -615,7 +615,7 @@ static inline void mmu_notifier_range_init_owner(
 	pud_t ___pud;							\
 									\
 	___pud = pudp_huge_clear_flush(__vma, __haddr, __pud);		\
-	mmu_notifier_invalidate_range(___mm, ___haddr,			\
+	mmu_notifier_arch_invalidate_secondary_tlbs(___mm, ___haddr,		\
 				      ___haddr + HPAGE_PUD_SIZE);	\
 									\
 	___pud;								\
@@ -716,7 +716,7 @@ mmu_notifier_invalidate_range_only_end(struct mmu_notifier_range *range)
 {
 }
 
-static inline void mmu_notifier_invalidate_range(struct mm_struct *mm,
+static inline void mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
 				  unsigned long start, unsigned long end)
 {
 }
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index eb36783..a232891 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2124,8 +2124,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 	if (is_huge_zero_pmd(*pmd)) {
 		/*
 		 * FIXME: Do we want to invalidate secondary mmu by calling
-		 * mmu_notifier_invalidate_range() see comments below inside
-		 * __split_huge_pmd() ?
+		 * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below
+		 * inside __split_huge_pmd() ?
 		 *
 		 * We are going from a zero huge page write protected to zero
 		 * small page also write protected so it does not seems useful
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 64a3239..178c930 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5690,7 +5690,8 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
 
 		/* Break COW or unshare */
 		huge_ptep_clear_flush(vma, haddr, ptep);
-		mmu_notifier_invalidate_range(mm, range.start, range.end);
+		mmu_notifier_arch_invalidate_secondary_tlbs(mm, range.start,
+						range.end);
 		page_remove_rmap(&old_folio->page, vma, true);
 		hugepage_add_new_anon_rmap(new_folio, vma, haddr);
 		if (huge_pte_uffd_wp(pte))
@@ -6822,8 +6823,9 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
 	else
 		flush_hugetlb_tlb_range(vma, start, end);
 	/*
-	 * No need to call mmu_notifier_invalidate_range() we are downgrading
-	 * page table protection not changing it to point to a new page.
+	 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs() we are
+	 * downgrading page table protection not changing it to point to a new
+	 * page.
 	 *
 	 * See Documentation/mm/mmu_notifier.rst
 	 */
@@ -7467,7 +7469,7 @@ static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
 	i_mmap_unlock_write(vma->vm_file->f_mapping);
 	hugetlb_vma_unlock_write(vma);
 	/*
-	 * No need to call mmu_notifier_invalidate_range(), see
+	 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs(), see
 	 * Documentation/mm/mmu_notifier.rst.
 	 */
 	mmu_notifier_invalidate_range_end(&range);
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 50c0dde..34c5a84 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -207,7 +207,7 @@ mmu_interval_read_begin(struct mmu_interval_notifier *interval_sub)
 	 *    spin_lock
 	 *     seq = ++subscriptions->invalidate_seq
 	 *    spin_unlock
-	 *     op->invalidate_range():
+	 *     op->invalidate_secondary_tlbs():
 	 *       user_lock
 	 *        mmu_interval_set_seq()
 	 *         interval_sub->invalidate_seq = seq
@@ -560,23 +560,23 @@ mn_hlist_invalidate_end(struct mmu_notifier_subscriptions *subscriptions,
 	hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist,
 				 srcu_read_lock_held(&srcu)) {
 		/*
-		 * Call invalidate_range here too to avoid the need for the
-		 * subsystem of having to register an invalidate_range_end
-		 * call-back when there is invalidate_range already. Usually a
-		 * subsystem registers either invalidate_range_start()/end() or
-		 * invalidate_range(), so this will be no additional overhead
-		 * (besides the pointer check).
+		 * Subsystems should register either invalidate_secondary_tlbs()
+		 * or invalidate_range_start()/end() callbacks.
 		 *
-		 * We skip call to invalidate_range() if we know it is safe ie
-		 * call site use mmu_notifier_invalidate_range_only_end() which
-		 * is safe to do when we know that a call to invalidate_range()
-		 * already happen under page table lock.
+		 * We call invalidate_secondary_tlbs() here so that subsystems
+		 * can use larger range based invalidations. In some cases
+		 * though invalidate_secondary_tlbs() needs to be called while
+		 * holding the page table lock. In that case call sites use
+		 * mmu_notifier_invalidate_range_only_end() and we know it is
+		 * safe to skip secondary TLB invalidation as it will have
+		 * already been done.
 		 */
-		if (!only_end && subscription->ops->invalidate_range)
-			subscription->ops->invalidate_range(subscription,
-							    range->mm,
-							    range->start,
-							    range->end);
+		if (!only_end && subscription->ops->invalidate_secondary_tlbs)
+			subscription->ops->invalidate_secondary_tlbs(
+				subscription,
+				range->mm,
+				range->start,
+				range->end);
 		if (subscription->ops->invalidate_range_end) {
 			if (!mmu_notifier_range_blockable(range))
 				non_block_start();
@@ -604,8 +604,8 @@ void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range,
 	lock_map_release(&__mmu_notifier_invalidate_range_start_map);
 }
 
-void __mmu_notifier_invalidate_range(struct mm_struct *mm,
-				  unsigned long start, unsigned long end)
+void __mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
+					unsigned long start, unsigned long end)
 {
 	struct mmu_notifier *subscription;
 	int id;
@@ -614,9 +614,10 @@ void __mmu_notifier_invalidate_range(struct mm_struct *mm,
 	hlist_for_each_entry_rcu(subscription,
 				 &mm->notifier_subscriptions->list, hlist,
 				 srcu_read_lock_held(&srcu)) {
-		if (subscription->ops->invalidate_range)
-			subscription->ops->invalidate_range(subscription, mm,
-							    start, end);
+		if (subscription->ops->arch_invalidate_secondary_tlbs)
+			subscription->ops->arch_invalidate_secondary_tlbs(
+				subscription, mm,
+				start, end);
 	}
 	srcu_read_unlock(&srcu, id);
 }
@@ -635,6 +636,15 @@ int __mmu_notifier_register(struct mmu_notifier *subscription,
 	mmap_assert_write_locked(mm);
 	BUG_ON(atomic_read(&mm->mm_users) <= 0);
 
+	/*
+	 * Subsystems should only register for invalidate_secondary_tlbs() or
+	 * invalidate_range_start()/end() callbacks, not both.
+	 */
+	if (WARN_ON_ONCE(subscription->ops->arch_invalidate_secondary_tlbs &&
+				(subscription->ops->invalidate_range_start ||
+				subscription->ops->invalidate_range_end)))
+		return -EINVAL;
+
 	if (!mm->notifier_subscriptions) {
 		/*
 		 * kmalloc cannot be called under mm_take_all_locks(), but we
diff --git a/mm/rmap.c b/mm/rmap.c
index 0c0d885..b74fc2c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -991,9 +991,9 @@ static int page_vma_mkclean_one(struct page_vma_mapped_walk *pvmw)
 		}
 
 		/*
-		 * No need to call mmu_notifier_invalidate_range() as we are
-		 * downgrading page table protection not changing it to point
-		 * to a new page.
+		 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs() as
+		 * we are downgrading page table protection not changing it to
+		 * point to a new page.
 		 *
 		 * See Documentation/mm/mmu_notifier.rst
 		 */
@@ -1554,8 +1554,8 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 					hugetlb_vma_unlock_write(vma);
 					flush_tlb_range(vma,
 						range.start, range.end);
-					mmu_notifier_invalidate_range(mm,
-						range.start, range.end);
+					mmu_notifier_arch_invalidate_secondary_tlbs(
+						mm, range.start, range.end);
 					/*
 					 * The ref count of the PMD page was
 					 * dropped which is part of the way map
@@ -1629,7 +1629,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 			 */
 			dec_mm_counter(mm, mm_counter(&folio->page));
 			/* We have to invalidate as we cleared the pte */
-			mmu_notifier_invalidate_range(mm, address,
+			mmu_notifier_arch_invalidate_secondary_tlbs(mm, address,
 						      address + PAGE_SIZE);
 		} else if (folio_test_anon(folio)) {
 			swp_entry_t entry = { .val = page_private(subpage) };
@@ -1643,7 +1643,8 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 				WARN_ON_ONCE(1);
 				ret = false;
 				/* We have to invalidate as we cleared the pte */
-				mmu_notifier_invalidate_range(mm, address,
+				mmu_notifier_arch_invalidate_secondary_tlbs(mm,
+							address,
 							address + PAGE_SIZE);
 				page_vma_mapped_walk_done(&pvmw);
 				break;
@@ -1676,8 +1677,9 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 				if (ref_count == 1 + map_count &&
 				    !folio_test_dirty(folio)) {
 					/* Invalidate as we cleared the pte */
-					mmu_notifier_invalidate_range(mm,
-						address, address + PAGE_SIZE);
+					mmu_notifier_arch_invalidate_secondary_tlbs(
+						mm, address,
+						address + PAGE_SIZE);
 					dec_mm_counter(mm, MM_ANONPAGES);
 					goto discard;
 				}
@@ -1733,7 +1735,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 				swp_pte = pte_swp_mkuffd_wp(swp_pte);
 			set_pte_at(mm, address, pvmw.pte, swp_pte);
 			/* Invalidate as we cleared the pte */
-			mmu_notifier_invalidate_range(mm, address,
+			mmu_notifier_arch_invalidate_secondary_tlbs(mm, address,
 						      address + PAGE_SIZE);
 		} else {
 			/*
@@ -1751,9 +1753,9 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 		}
 discard:
 		/*
-		 * No need to call mmu_notifier_invalidate_range() it has be
-		 * done above for all cases requiring it to happen under page
-		 * table lock before mmu_notifier_invalidate_range_end()
+		 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs() it
+		 * has be done above for all cases requiring it to happen under
+		 * page table lock before mmu_notifier_invalidate_range_end()
 		 *
 		 * See Documentation/mm/mmu_notifier.rst
 		 */
@@ -1935,8 +1937,8 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 					hugetlb_vma_unlock_write(vma);
 					flush_tlb_range(vma,
 						range.start, range.end);
-					mmu_notifier_invalidate_range(mm,
-						range.start, range.end);
+					mmu_notifier_arch_invalidate_secondary_tlbs(
+						mm, range.start, range.end);
 
 					/*
 					 * The ref count of the PMD page was
@@ -2042,8 +2044,8 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 			 */
 			dec_mm_counter(mm, mm_counter(&folio->page));
 			/* We have to invalidate as we cleared the pte */
-			mmu_notifier_invalidate_range(mm, address,
-						      address + PAGE_SIZE);
+			mmu_notifier_arch_invalidate_secondary_tlbs(mm, address,
+							address + PAGE_SIZE);
 		} else {
 			swp_entry_t entry;
 			pte_t swp_pte;
@@ -2108,9 +2110,9 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 		}
 
 		/*
-		 * No need to call mmu_notifier_invalidate_range() it has be
-		 * done above for all cases requiring it to happen under page
-		 * table lock before mmu_notifier_invalidate_range_end()
+		 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs() it
+		 * has be done above for all cases requiring it to happen under
+		 * page table lock before mmu_notifier_invalidate_range_end()
 		 *
 		 * See Documentation/mm/mmu_notifier.rst
 		 */
-- 
git-series 0.9.1

[PATCH 2/4] arm64/smmu: Use TLBI ASID when invalidating entire range

[Alistair Popple]

The ARM SMMU has a specific command for invalidating the TLB for an
entire ASID. Currently this is used for the IO_PGTABLE API but not for
ATS when called from the MMU notifier.

The current implementation of notifiers does not attempt to invalidate
such a large address range, instead walking each VMA and invalidating
each range individually during mmap removal. However in future SMMU
TLB invalidations are going to be sent as part of the normal
flush_tlb_*() kernel calls. To better deal with that add handling to
use TLBI ASID when invalidating the entire address space.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
index aa63cff..dbc812a 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
@@ -201,10 +201,20 @@ static void arm_smmu_mm_arch_invalidate_secondary_tlbs(struct mmu_notifier *mn,
 	 * range. So do a simple translation here by calculating size correctly.
 	 */
 	size = end - start;
+	if (size == ULONG_MAX)
+		size = 0;
+
+	if (!(smmu_domain->smmu->features & ARM_SMMU_FEAT_BTM)) {
+		if (!size)
+			arm_smmu_tlb_inv_asid(smmu_domain->smmu,
+					      smmu_mn->cd->asid);
+		else
+			arm_smmu_tlb_inv_range_asid(start, size,
+						    smmu_mn->cd->asid,
+						    PAGE_SIZE, false,
+						    smmu_domain);
+	}
 
-	if (!(smmu_domain->smmu->features & ARM_SMMU_FEAT_BTM))
-		arm_smmu_tlb_inv_range_asid(start, size, smmu_mn->cd->asid,
-					    PAGE_SIZE, false, smmu_domain);
 	arm_smmu_atc_inv_domain(smmu_domain, mm->pasid, start, size);
 }
 
-- 
git-series 0.9.1

[PATCH 3/4] mmu_notifiers: Call arch_invalidate_secondary_tlbs() when invalidating TLBs

[Alistair Popple]

The arch_invalidate_secondary_tlbs() is an architecture specific mmu
notifier used to keep the TLB of secondary MMUs such as an IOMMU in
sync with the CPU page tables. Currently it is called from separate
code paths to the main CPU TLB invalidations. This can lead to a
secondary TLB not getting invalidated when required and makes it hard
to reason about when exactly the secondary TLB is invalidated.

To fix this move the notifier call to the architecture specific TLB
maintenance functions for architectures that have secondary MMUs
requiring explicit software invalidations.

This fixes a SMMU bug on ARM64. On ARM64 PTE permission upgrades
require a TLB invalidation. This invalidation is done by the
architecutre specific ptep_set_access_flags() which calls
flush_tlb_page() if required. However this doesn't call the notifier
resulting in infinite faults being generated by devices using the SMMU
if it has previously cached a read-only PTE in it's TLB.

Moving the invalidations into the TLB invalidation functions ensures
all invalidations happen at the same time as the CPU invalidation. The
architecture specific flush_tlb_all() routines do not call the
notifier as none of the IOMMUs require this.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Suggested-by: Jason Gunthorpe <jgg@ziepe.ca>
---
 arch/arm64/include/asm/tlbflush.h             | 5 +++++
 arch/powerpc/include/asm/book3s/64/tlbflush.h | 1 +
 arch/powerpc/mm/book3s64/radix_hugetlbpage.c  | 1 +
 arch/powerpc/mm/book3s64/radix_tlb.c          | 6 ++++++
 arch/x86/mm/tlb.c                             | 2 ++
 include/asm-generic/tlb.h                     | 1 -
 6 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index 412a3b9..386f0f7 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -13,6 +13,7 @@
 #include <linux/bitfield.h>
 #include <linux/mm_types.h>
 #include <linux/sched.h>
+#include <linux/mmu_notifier.h>
 #include <asm/cputype.h>
 #include <asm/mmu.h>
 
@@ -252,6 +253,7 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
 	__tlbi(aside1is, asid);
 	__tlbi_user(aside1is, asid);
 	dsb(ish);
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, 0, -1UL);
 }
 
 static inline void flush_tlb_page_nosync(struct vm_area_struct *vma,
@@ -263,6 +265,8 @@ static inline void flush_tlb_page_nosync(struct vm_area_struct *vma,
 	addr = __TLBI_VADDR(uaddr, ASID(vma->vm_mm));
 	__tlbi(vale1is, addr);
 	__tlbi_user(vale1is, addr);
+	mmu_notifier_arch_invalidate_secondary_tlbs(vma->vm_mm, uaddr & PAGE_MASK,
+						(uaddr & PAGE_MASK) + PAGE_SIZE);
 }
 
 static inline void flush_tlb_page(struct vm_area_struct *vma,
@@ -358,6 +362,7 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
 		scale++;
 	}
 	dsb(ish);
+	mmu_notifier_arch_invalidate_secondary_tlbs(vma->vm_mm, start, end);
 }
 
 static inline void flush_tlb_range(struct vm_area_struct *vma,
diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush.h b/arch/powerpc/include/asm/book3s/64/tlbflush.h
index 0d0c144..dca0477 100644
--- a/arch/powerpc/include/asm/book3s/64/tlbflush.h
+++ b/arch/powerpc/include/asm/book3s/64/tlbflush.h
@@ -5,6 +5,7 @@
 #define MMU_NO_CONTEXT	~0UL
 
 #include <linux/mm_types.h>
+#include <linux/mmu_notifier.h>
 #include <asm/book3s/64/tlbflush-hash.h>
 #include <asm/book3s/64/tlbflush-radix.h>
 
diff --git a/arch/powerpc/mm/book3s64/radix_hugetlbpage.c b/arch/powerpc/mm/book3s64/radix_hugetlbpage.c
index 5e31955..17075c7 100644
--- a/arch/powerpc/mm/book3s64/radix_hugetlbpage.c
+++ b/arch/powerpc/mm/book3s64/radix_hugetlbpage.c
@@ -39,6 +39,7 @@ void radix__flush_hugetlb_tlb_range(struct vm_area_struct *vma, unsigned long st
 		radix__flush_tlb_pwc_range_psize(vma->vm_mm, start, end, psize);
 	else
 		radix__flush_tlb_range_psize(vma->vm_mm, start, end, psize);
+	mmu_notifier_arch_invalidate_secondary_tlbs(vma->vm_mm, start, end);
 }
 
 void radix__huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c
index 0bd4866..64c11a4 100644
--- a/arch/powerpc/mm/book3s64/radix_tlb.c
+++ b/arch/powerpc/mm/book3s64/radix_tlb.c
@@ -752,6 +752,8 @@ void radix__local_flush_tlb_page(struct vm_area_struct *vma, unsigned long vmadd
 		return radix__local_flush_hugetlb_page(vma, vmaddr);
 #endif
 	radix__local_flush_tlb_page_psize(vma->vm_mm, vmaddr, mmu_virtual_psize);
+	mmu_notifier_arch_invalidate_secondary_tlbs(vma->vm_mm, vmaddr,
+						vmaddr + mmu_virtual_psize);
 }
 EXPORT_SYMBOL(radix__local_flush_tlb_page);
 
@@ -987,6 +989,7 @@ void radix__flush_tlb_mm(struct mm_struct *mm)
 		}
 	}
 	preempt_enable();
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, 0, -1UL);
 }
 EXPORT_SYMBOL(radix__flush_tlb_mm);
 
@@ -1020,6 +1023,7 @@ static void __flush_all_mm(struct mm_struct *mm, bool fullmm)
 			_tlbiel_pid_multicast(mm, pid, RIC_FLUSH_ALL);
 	}
 	preempt_enable();
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, 0, -1UL);
 }
 
 void radix__flush_all_mm(struct mm_struct *mm)
@@ -1228,6 +1232,7 @@ static inline void __radix__flush_tlb_range(struct mm_struct *mm,
 	}
 out:
 	preempt_enable();
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, end);
 }
 
 void radix__flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
@@ -1392,6 +1397,7 @@ static void __radix__flush_tlb_range_psize(struct mm_struct *mm,
 	}
 out:
 	preempt_enable();
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, end);
 }
 
 void radix__flush_tlb_range_psize(struct mm_struct *mm, unsigned long start,
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index eaefc10..0b990fb 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -1037,6 +1037,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 
 	put_flush_tlb_info();
 	put_cpu();
+	mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, end);
 }
 
 
@@ -1264,6 +1265,7 @@ void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
 
 	put_flush_tlb_info();
 	put_cpu();
+	mmu_notifier_arch_invalidate_secondary_tlbs(current->mm, 0, -1UL);
 }
 
 /*
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 48c81b9..bc32a22 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -456,7 +456,6 @@ static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
 		return;
 
 	tlb_flush(tlb);
-	mmu_notifier_invalidate_secondary_tlbs(tlb->mm, tlb->start, tlb->end);
 	__tlb_reset_range(tlb);
 }
 
-- 
git-series 0.9.1

[PATCH 4/4] mmu_notifiers: Don't invalidate secondary TLBs as part of mmu_notifier_invalidate_range_end()

[Alistair Popple]

Secondary TLBs are now invalidated from the architecture specific TLB
invalidation functions. Therefore there is no need to explicitly
notify or invalidate as part of the range end functions. This means we
can remove mmu_notifier_invalidate_range_end_only() and some of the
ptep_*_notify() functions.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 include/linux/mmu_notifier.h | 56 +------------------------------------
 kernel/events/uprobes.c      |  2 +-
 mm/huge_memory.c             | 25 ++---------------
 mm/hugetlb.c                 |  2 +-
 mm/memory.c                  |  8 +----
 mm/migrate_device.c          |  9 +-----
 mm/mmu_notifier.c            | 25 ++---------------
 mm/rmap.c                    | 42 +----------------------------
 8 files changed, 14 insertions(+), 155 deletions(-)

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index a4bc818..6e3c857 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -395,8 +395,7 @@ extern int __mmu_notifier_test_young(struct mm_struct *mm,
 extern void __mmu_notifier_change_pte(struct mm_struct *mm,
 				      unsigned long address, pte_t pte);
 extern int __mmu_notifier_invalidate_range_start(struct mmu_notifier_range *r);
-extern void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *r,
-				  bool only_end);
+extern void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *r);
 extern void __mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
 					unsigned long start, unsigned long end);
 extern bool
@@ -481,14 +480,7 @@ mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range)
 		might_sleep();
 
 	if (mm_has_notifiers(range->mm))
-		__mmu_notifier_invalidate_range_end(range, false);
-}
-
-static inline void
-mmu_notifier_invalidate_range_only_end(struct mmu_notifier_range *range)
-{
-	if (mm_has_notifiers(range->mm))
-		__mmu_notifier_invalidate_range_end(range, true);
+		__mmu_notifier_invalidate_range_end(range);
 }
 
 static inline void mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
@@ -582,45 +574,6 @@ static inline void mmu_notifier_range_init_owner(
 	__young;							\
 })
 
-#define	ptep_clear_flush_notify(__vma, __address, __ptep)		\
-({									\
-	unsigned long ___addr = __address & PAGE_MASK;			\
-	struct mm_struct *___mm = (__vma)->vm_mm;			\
-	pte_t ___pte;							\
-									\
-	___pte = ptep_clear_flush(__vma, __address, __ptep);		\
-	mmu_notifier_arch_invalidate_secondary_tlbs(___mm, ___addr,		\
-					___addr + PAGE_SIZE);		\
-									\
-	___pte;								\
-})
-
-#define pmdp_huge_clear_flush_notify(__vma, __haddr, __pmd)		\
-({									\
-	unsigned long ___haddr = __haddr & HPAGE_PMD_MASK;		\
-	struct mm_struct *___mm = (__vma)->vm_mm;			\
-	pmd_t ___pmd;							\
-									\
-	___pmd = pmdp_huge_clear_flush(__vma, __haddr, __pmd);		\
-	mmu_notifier_arch_invalidate_secondary_tlbs(___mm, ___haddr,		\
-				      ___haddr + HPAGE_PMD_SIZE);	\
-									\
-	___pmd;								\
-})
-
-#define pudp_huge_clear_flush_notify(__vma, __haddr, __pud)		\
-({									\
-	unsigned long ___haddr = __haddr & HPAGE_PUD_MASK;		\
-	struct mm_struct *___mm = (__vma)->vm_mm;			\
-	pud_t ___pud;							\
-									\
-	___pud = pudp_huge_clear_flush(__vma, __haddr, __pud);		\
-	mmu_notifier_arch_invalidate_secondary_tlbs(___mm, ___haddr,		\
-				      ___haddr + HPAGE_PUD_SIZE);	\
-									\
-	___pud;								\
-})
-
 /*
  * set_pte_at_notify() sets the pte _after_ running the notifier.
  * This is safe to start by updating the secondary MMUs, because the primary MMU
@@ -711,11 +664,6 @@ void mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range)
 {
 }
 
-static inline void
-mmu_notifier_invalidate_range_only_end(struct mmu_notifier_range *range)
-{
-}
-
 static inline void mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm,
 				  unsigned long start, unsigned long end)
 {
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index f0ac5b8..3048589 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -193,7 +193,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 	}
 
 	flush_cache_page(vma, addr, pte_pfn(ptep_get(pvmw.pte)));
-	ptep_clear_flush_notify(vma, addr, pvmw.pte);
+	ptep_clear_flush(vma, addr, pvmw.pte);
 	if (new_page)
 		set_pte_at_notify(mm, addr, pvmw.pte,
 				  mk_pte(new_page, vma->vm_page_prot));
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a232891..c80d0f9 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2003,7 +2003,7 @@ static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
 
 	count_vm_event(THP_SPLIT_PUD);
 
-	pudp_huge_clear_flush_notify(vma, haddr, pud);
+	pudp_huge_clear_flush(vma, haddr, pud);
 }
 
 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
@@ -2023,11 +2023,7 @@ void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
 
 out:
 	spin_unlock(ptl);
-	/*
-	 * No need to double call mmu_notifier->invalidate_range() callback as
-	 * the above pudp_huge_clear_flush_notify() did already call it.
-	 */
-	mmu_notifier_invalidate_range_only_end(&range);
+	mmu_notifier_invalidate_range_end(&range);
 }
 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 
@@ -2094,7 +2090,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 	count_vm_event(THP_SPLIT_PMD);
 
 	if (!vma_is_anonymous(vma)) {
-		old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+		old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd);
 		/*
 		 * We are going to unmap this huge page. So
 		 * just go ahead and zap it
@@ -2304,20 +2300,7 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 
 out:
 	spin_unlock(ptl);
-	/*
-	 * No need to double call mmu_notifier->invalidate_range() callback.
-	 * They are 3 cases to consider inside __split_huge_pmd_locked():
-	 *  1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
-	 *  2) __split_huge_zero_page_pmd() read only zero page and any write
-	 *    fault will trigger a flush_notify before pointing to a new page
-	 *    (it is fine if the secondary mmu keeps pointing to the old zero
-	 *    page in the meantime)
-	 *  3) Split a huge pmd into pte pointing to the same page. No need
-	 *     to invalidate secondary tlb entry they are all still valid.
-	 *     any further changes to individual pte will notify. So no need
-	 *     to call mmu_notifier->invalidate_range()
-	 */
-	mmu_notifier_invalidate_range_only_end(&range);
+	mmu_notifier_invalidate_range_end(&range);
 }
 
 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 178c930..b903377 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5690,8 +5690,6 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
 
 		/* Break COW or unshare */
 		huge_ptep_clear_flush(vma, haddr, ptep);
-		mmu_notifier_arch_invalidate_secondary_tlbs(mm, range.start,
-						range.end);
 		page_remove_rmap(&old_folio->page, vma, true);
 		hugepage_add_new_anon_rmap(new_folio, vma, haddr);
 		if (huge_pte_uffd_wp(pte))
diff --git a/mm/memory.c b/mm/memory.c
index 01f39e8..fbfcc01 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3149,7 +3149,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 		 * that left a window where the new PTE could be loaded into
 		 * some TLBs while the old PTE remains in others.
 		 */
-		ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
+		ptep_clear_flush(vma, vmf->address, vmf->pte);
 		folio_add_new_anon_rmap(new_folio, vma, vmf->address);
 		folio_add_lru_vma(new_folio, vma);
 		/*
@@ -3195,11 +3195,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 		pte_unmap_unlock(vmf->pte, vmf->ptl);
 	}
 
-	/*
-	 * No need to double call mmu_notifier->invalidate_range() callback as
-	 * the above ptep_clear_flush_notify() did already call it.
-	 */
-	mmu_notifier_invalidate_range_only_end(&range);
+	mmu_notifier_invalidate_range_end(&range);
 
 	if (new_folio)
 		folio_put(new_folio);
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 8365158..9ce8214 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -658,7 +658,7 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
 
 	if (flush) {
 		flush_cache_page(vma, addr, pte_pfn(orig_pte));
-		ptep_clear_flush_notify(vma, addr, ptep);
+		ptep_clear_flush(vma, addr, ptep);
 		set_pte_at_notify(mm, addr, ptep, entry);
 		update_mmu_cache(vma, addr, ptep);
 	} else {
@@ -754,13 +754,8 @@ static void __migrate_device_pages(unsigned long *src_pfns,
 			src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
 	}
 
-	/*
-	 * No need to double call mmu_notifier->invalidate_range() callback as
-	 * the above ptep_clear_flush_notify() inside migrate_vma_insert_page()
-	 * did already call it.
-	 */
 	if (notified)
-		mmu_notifier_invalidate_range_only_end(&range);
+		mmu_notifier_invalidate_range_end(&range);
 }
 
 /**
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 34c5a84..42bcc0a 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -551,7 +551,7 @@ int __mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
 
 static void
 mn_hlist_invalidate_end(struct mmu_notifier_subscriptions *subscriptions,
-			struct mmu_notifier_range *range, bool only_end)
+			struct mmu_notifier_range *range)
 {
 	struct mmu_notifier *subscription;
 	int id;
@@ -559,24 +559,6 @@ mn_hlist_invalidate_end(struct mmu_notifier_subscriptions *subscriptions,
 	id = srcu_read_lock(&srcu);
 	hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist,
 				 srcu_read_lock_held(&srcu)) {
-		/*
-		 * Subsystems should register either invalidate_secondary_tlbs()
-		 * or invalidate_range_start()/end() callbacks.
-		 *
-		 * We call invalidate_secondary_tlbs() here so that subsystems
-		 * can use larger range based invalidations. In some cases
-		 * though invalidate_secondary_tlbs() needs to be called while
-		 * holding the page table lock. In that case call sites use
-		 * mmu_notifier_invalidate_range_only_end() and we know it is
-		 * safe to skip secondary TLB invalidation as it will have
-		 * already been done.
-		 */
-		if (!only_end && subscription->ops->invalidate_secondary_tlbs)
-			subscription->ops->invalidate_secondary_tlbs(
-				subscription,
-				range->mm,
-				range->start,
-				range->end);
 		if (subscription->ops->invalidate_range_end) {
 			if (!mmu_notifier_range_blockable(range))
 				non_block_start();
@@ -589,8 +571,7 @@ mn_hlist_invalidate_end(struct mmu_notifier_subscriptions *subscriptions,
 	srcu_read_unlock(&srcu, id);
 }
 
-void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range,
-					 bool only_end)
+void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range)
 {
 	struct mmu_notifier_subscriptions *subscriptions =
 		range->mm->notifier_subscriptions;
@@ -600,7 +581,7 @@ void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range,
 		mn_itree_inv_end(subscriptions);
 
 	if (!hlist_empty(&subscriptions->list))
-		mn_hlist_invalidate_end(subscriptions, range, only_end);
+		mn_hlist_invalidate_end(subscriptions, range);
 	lock_map_release(&__mmu_notifier_invalidate_range_start_map);
 }
 
diff --git a/mm/rmap.c b/mm/rmap.c
index b74fc2c..1fbe83e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -990,13 +990,6 @@ static int page_vma_mkclean_one(struct page_vma_mapped_walk *pvmw)
 #endif
 		}
 
-		/*
-		 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs() as
-		 * we are downgrading page table protection not changing it to
-		 * point to a new page.
-		 *
-		 * See Documentation/mm/mmu_notifier.rst
-		 */
 		if (ret)
 			cleaned++;
 	}
@@ -1554,8 +1547,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 					hugetlb_vma_unlock_write(vma);
 					flush_tlb_range(vma,
 						range.start, range.end);
-					mmu_notifier_arch_invalidate_secondary_tlbs(
-						mm, range.start, range.end);
 					/*
 					 * The ref count of the PMD page was
 					 * dropped which is part of the way map
@@ -1628,9 +1619,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 			 * copied pages.
 			 */
 			dec_mm_counter(mm, mm_counter(&folio->page));
-			/* We have to invalidate as we cleared the pte */
-			mmu_notifier_arch_invalidate_secondary_tlbs(mm, address,
-						      address + PAGE_SIZE);
 		} else if (folio_test_anon(folio)) {
 			swp_entry_t entry = { .val = page_private(subpage) };
 			pte_t swp_pte;
@@ -1642,10 +1630,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 					folio_test_swapcache(folio))) {
 				WARN_ON_ONCE(1);
 				ret = false;
-				/* We have to invalidate as we cleared the pte */
-				mmu_notifier_arch_invalidate_secondary_tlbs(mm,
-							address,
-							address + PAGE_SIZE);
 				page_vma_mapped_walk_done(&pvmw);
 				break;
 			}
@@ -1676,10 +1660,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 				 */
 				if (ref_count == 1 + map_count &&
 				    !folio_test_dirty(folio)) {
-					/* Invalidate as we cleared the pte */
-					mmu_notifier_arch_invalidate_secondary_tlbs(
-						mm, address,
-						address + PAGE_SIZE);
 					dec_mm_counter(mm, MM_ANONPAGES);
 					goto discard;
 				}
@@ -1734,9 +1714,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 			if (pte_uffd_wp(pteval))
 				swp_pte = pte_swp_mkuffd_wp(swp_pte);
 			set_pte_at(mm, address, pvmw.pte, swp_pte);
-			/* Invalidate as we cleared the pte */
-			mmu_notifier_arch_invalidate_secondary_tlbs(mm, address,
-						      address + PAGE_SIZE);
 		} else {
 			/*
 			 * This is a locked file-backed folio,
@@ -1752,13 +1729,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 			dec_mm_counter(mm, mm_counter_file(&folio->page));
 		}
 discard:
-		/*
-		 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs() it
-		 * has be done above for all cases requiring it to happen under
-		 * page table lock before mmu_notifier_invalidate_range_end()
-		 *
-		 * See Documentation/mm/mmu_notifier.rst
-		 */
 		page_remove_rmap(subpage, vma, folio_test_hugetlb(folio));
 		if (vma->vm_flags & VM_LOCKED)
 			mlock_drain_local();
@@ -1937,8 +1907,6 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 					hugetlb_vma_unlock_write(vma);
 					flush_tlb_range(vma,
 						range.start, range.end);
-					mmu_notifier_arch_invalidate_secondary_tlbs(
-						mm, range.start, range.end);
 
 					/*
 					 * The ref count of the PMD page was
@@ -2043,9 +2011,6 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 			 * copied pages.
 			 */
 			dec_mm_counter(mm, mm_counter(&folio->page));
-			/* We have to invalidate as we cleared the pte */
-			mmu_notifier_arch_invalidate_secondary_tlbs(mm, address,
-							address + PAGE_SIZE);
 		} else {
 			swp_entry_t entry;
 			pte_t swp_pte;
@@ -2109,13 +2074,6 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 			 */
 		}
 
-		/*
-		 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs() it
-		 * has be done above for all cases requiring it to happen under
-		 * page table lock before mmu_notifier_invalidate_range_end()
-		 *
-		 * See Documentation/mm/mmu_notifier.rst
-		 */
 		page_remove_rmap(subpage, vma, folio_test_hugetlb(folio));
 		if (vma->vm_flags & VM_LOCKED)
 			mlock_drain_local();
-- 
git-series 0.9.1

Re: [PATCH 1/4] mm_notifiers: Rename invalidate_range notifier

[Jason Gunthorpe]

On Tue, Jul 18, 2023 at 05:56:15PM +1000, Alistair Popple wrote:
> diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
> index b466172..48c81b9 100644
> --- a/include/asm-generic/tlb.h
> +++ b/include/asm-generic/tlb.h
> @@ -456,7 +456,7 @@ static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
>  		return;
>  
>  	tlb_flush(tlb);
> -	mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
> +	mmu_notifier_invalidate_secondary_tlbs(tlb->mm, tlb->start, tlb->end);
>  	__tlb_reset_range(tlb);

Does this compile? I don't see
"mmu_notifier_invalidate_secondary_tlbs" ?

Maybe we don't need to rename this function since you pretty much
remove it in the next patches?

> diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
> index 50c0dde..34c5a84 100644
> --- a/mm/mmu_notifier.c
> +++ b/mm/mmu_notifier.c
> @@ -207,7 +207,7 @@ mmu_interval_read_begin(struct mmu_interval_notifier *interval_sub)
>  	 *    spin_lock
>  	 *     seq = ++subscriptions->invalidate_seq
>  	 *    spin_unlock
> -	 *     op->invalidate_range():
> +	 *     op->invalidate_secondary_tlbs():

The later patch should delete this stuff from the comment too, we
no longer guarantee this relationship?

> @@ -560,23 +560,23 @@ mn_hlist_invalidate_end(struct mmu_notifier_subscriptions *subscriptions,
>  	hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist,
>  				 srcu_read_lock_held(&srcu)) {
>  		/*
> -		 * Call invalidate_range here too to avoid the need for the
> -		 * subsystem of having to register an invalidate_range_end
> -		 * call-back when there is invalidate_range already. Usually a
> -		 * subsystem registers either invalidate_range_start()/end() or
> -		 * invalidate_range(), so this will be no additional overhead
> -		 * (besides the pointer check).
> +		 * Subsystems should register either invalidate_secondary_tlbs()
> +		 * or invalidate_range_start()/end() callbacks.
>  		 *
> -		 * We skip call to invalidate_range() if we know it is safe ie
> -		 * call site use mmu_notifier_invalidate_range_only_end() which
> -		 * is safe to do when we know that a call to invalidate_range()
> -		 * already happen under page table lock.
> +		 * We call invalidate_secondary_tlbs() here so that subsystems
> +		 * can use larger range based invalidations. In some cases
> +		 * though invalidate_secondary_tlbs() needs to be called while
> +		 * holding the page table lock. In that case call sites use
> +		 * mmu_notifier_invalidate_range_only_end() and we know it is
> +		 * safe to skip secondary TLB invalidation as it will have
> +		 * already been done.
>  		 */
> -		if (!only_end && subscription->ops->invalidate_range)
> -			subscription->ops->invalidate_range(subscription,
> -							    range->mm,
> -							    range->start,
> -							    range->end);
> +		if (!only_end && subscription->ops->invalidate_secondary_tlbs)
> +			subscription->ops->invalidate_secondary_tlbs(

More doesn't compile, and the comment has the same issue..

But I think the approach in this series looks fine, it is so much
cleaner after we remove all the cruft in patch 4, just look at the
diffstat..

Jason

Re: [PATCH 3/4] mmu_notifiers: Call arch_invalidate_secondary_tlbs() when invalidating TLBs

[Andrew Morton]

On Tue, 18 Jul 2023 17:56:17 +1000 Alistair Popple <apopple@nvidia.com> wrote:

> The arch_invalidate_secondary_tlbs() is an architecture specific mmu
> notifier used to keep the TLB of secondary MMUs such as an IOMMU in
> sync with the CPU page tables. Currently it is called from separate
> code paths to the main CPU TLB invalidations. This can lead to a
> secondary TLB not getting invalidated when required and makes it hard
> to reason about when exactly the secondary TLB is invalidated.
> 
> To fix this move the notifier call to the architecture specific TLB
> maintenance functions for architectures that have secondary MMUs
> requiring explicit software invalidations.
> 
> This fixes a SMMU bug on ARM64. On ARM64 PTE permission upgrades
> require a TLB invalidation. This invalidation is done by the
> architecutre specific ptep_set_access_flags() which calls
> flush_tlb_page() if required. However this doesn't call the notifier
> resulting in infinite faults being generated by devices using the SMMU
> if it has previously cached a read-only PTE in it's TLB.

This sounds like a pretty serious bug.  Can it happen in current
released kernels?  If so, is a -stable backport needed?

> Moving the invalidations into the TLB invalidation functions ensures
> all invalidations happen at the same time as the CPU invalidation. The
> architecture specific flush_tlb_all() routines do not call the
> notifier as none of the IOMMUs require this.

Re: [PATCH 3/4] mmu_notifiers: Call arch_invalidate_secondary_tlbs() when invalidating TLBs

[Jason Gunthorpe]

On Tue, Jul 18, 2023 at 11:17:59AM -0700, Andrew Morton wrote:
> On Tue, 18 Jul 2023 17:56:17 +1000 Alistair Popple <apopple@nvidia.com> wrote:
> 
> > The arch_invalidate_secondary_tlbs() is an architecture specific mmu
> > notifier used to keep the TLB of secondary MMUs such as an IOMMU in
> > sync with the CPU page tables. Currently it is called from separate
> > code paths to the main CPU TLB invalidations. This can lead to a
> > secondary TLB not getting invalidated when required and makes it hard
> > to reason about when exactly the secondary TLB is invalidated.
> > 
> > To fix this move the notifier call to the architecture specific TLB
> > maintenance functions for architectures that have secondary MMUs
> > requiring explicit software invalidations.
> > 
> > This fixes a SMMU bug on ARM64. On ARM64 PTE permission upgrades
> > require a TLB invalidation. This invalidation is done by the
> > architecutre specific ptep_set_access_flags() which calls
> > flush_tlb_page() if required. However this doesn't call the notifier
> > resulting in infinite faults being generated by devices using the SMMU
> > if it has previously cached a read-only PTE in it's TLB.
> 
> This sounds like a pretty serious bug.  Can it happen in current
> released kernels?  If so, is a -stable backport needed?

There are currently no in-kernel drivers using the IOMMU SVA API, so
the impact for -stable is sort of muted. But it is serious if you are
unlucky to hit it.

Jason

Re: [PATCH 1/4] mm_notifiers: Rename invalidate_range notifier

[Andrew Morton]

On Tue, 18 Jul 2023 14:57:12 -0300 Jason Gunthorpe <jgg@ziepe.ca> wrote:

> On Tue, Jul 18, 2023 at 05:56:15PM +1000, Alistair Popple wrote:
> > diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
> > index b466172..48c81b9 100644
> > --- a/include/asm-generic/tlb.h
> > +++ b/include/asm-generic/tlb.h
> > @@ -456,7 +456,7 @@ static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
> >  		return;
> >  
> >  	tlb_flush(tlb);
> > -	mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
> > +	mmu_notifier_invalidate_secondary_tlbs(tlb->mm, tlb->start, tlb->end);
> >  	__tlb_reset_range(tlb);
> 
> Does this compile? I don't see
> "mmu_notifier_invalidate_secondary_tlbs" ?

Seems this call gets deleted later in the series.

> But I think the approach in this series looks fine, it is so much
> cleaner after we remove all the cruft in patch 4, just look at the
> diffstat..

I'll push this into -next if it compiles OK for me, but yes, a redo is
desirable please.

Re: [PATCH 1/4] mm_notifiers: Rename invalidate_range notifier

[Alistair Popple]

Andrew Morton <akpm@linux-foundation.org> writes:

> On Tue, 18 Jul 2023 14:57:12 -0300 Jason Gunthorpe <jgg@ziepe.ca> wrote:
>
>> On Tue, Jul 18, 2023 at 05:56:15PM +1000, Alistair Popple wrote:
>> > diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
>> > index b466172..48c81b9 100644
>> > --- a/include/asm-generic/tlb.h
>> > +++ b/include/asm-generic/tlb.h
>> > @@ -456,7 +456,7 @@ static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
>> >  		return;
>> >  
>> >  	tlb_flush(tlb);
>> > -	mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
>> > +	mmu_notifier_invalidate_secondary_tlbs(tlb->mm, tlb->start, tlb->end);
>> >  	__tlb_reset_range(tlb);
>> 
>> Does this compile? I don't see
>> "mmu_notifier_invalidate_secondary_tlbs" ?

Dang, sorry. The original rename was to that but then we added *_arch_*
and I obviously missed some of the already renamed calls.

> Seems this call gets deleted later in the series.
>
>> But I think the approach in this series looks fine, it is so much
>> cleaner after we remove all the cruft in patch 4, just look at the
>> diffstat..
>
> I'll push this into -next if it compiles OK for me, but yes, a redo is
> desirable please.

Yep, will respin.

Re: [PATCH 0/4] Invalidate secondary IOMMU TLB on permission upgrade

[Anshuman Khandual]

On 7/18/23 13:26, Alistair Popple wrote:
> The main change is to move secondary TLB invalidation mmu notifier
> callbacks into the architecture specific TLB flushing functions. This
> makes secondary TLB invalidation mostly match CPU invalidation while
> still allowing efficient range based invalidations based on the
> existing TLB batching code.
> 
> ==========
> Background
> ==========
> 
> The arm64 architecture specifies TLB permission bits may be cached and
> therefore the TLB must be invalidated during permission upgrades. For
> the CPU this currently occurs in the architecture specific
> ptep_set_access_flags() routine.
> 
> Secondary TLBs such as implemented by the SMMU IOMMU match the CPU
> architecture specification and may also cache permission bits and
> require the same TLB invalidations. This may be achieved in one of two
> ways.
> 
> Some SMMU implementations implement broadcast TLB maintenance
> (BTM). This snoops CPU TLB invalidates and will invalidate any
> secondary TLB at the same time as the CPU. However implementations are
> not required to implement BTM.

So, the implementations with BTM do not even need a MMU notifier callback
for secondary TLB invalidation purpose ? Perhaps mmu_notifier_register()
could also be skipped for such cases i.e with ARM_SMMU_FEAT_BTM enabled ?

BTW, dont see ARM_SMMU_FEAT_BTM being added as a feature any where during
the probe i.e arm_smmu_device_hw_probe().

> 
> Implementations without BTM rely on mmu notifier callbacks to send
> explicit TLB invalidation commands to invalidate SMMU TLB. Therefore
> either generic kernel code or architecture specific code needs to call
> the mmu notifier on permission upgrade.
> 
> Currently that doesn't happen so devices will fault indefinitely when
> writing to a PTE that was previously read-only as nothing invalidates
> the SMMU TLB.

Why does not the current SMMU MMU notifier intercept all invalidation from
generic MM code and do the required secondary TLB invalidation ? Is there
a timing issue involved here ? Secondary TLB invalidation does happen but
after the damage has been done ? Could you please point us to a real world
bug report taking such indefinite faults as mentioned above ?

> 
> ========
> Solution
> ========
> 
> To fix this the series first renames the .invalidate_range() callback
> to .arch_invalidate_secondary_tlbs() as suggested by Jason and Sean to
> make it clear this callback is only used for secondary TLBs. That was
> made possible thanks to Sean's series [1] to remove KVM's incorrect
> usage.
> 
> Based on feedback from Jason [2] the proposed solution to the bug is
> to move the calls to mmu_notifier_arch_invalidate_secondary_tlbs()
> closer to the architecture specific TLB invalidation code. This
> ensures the secondary TLB won't miss invalidations, including the
> existing invalidation in the ARM64 code to deal with permission
> upgrade.

ptep_set_access_flags() is the only problematic place where this issue
is being reported ? If yes, why dont fix that instead of moving these
into platform specific callbacks ? OR there are other problematic areas
I might be missing.

> 
> Currently only ARM64, PowerPC and x86 have IOMMU with secondary TLBs
> requiring SW invalidation so the notifier is only called for those
> architectures. It is also not called for invalidation of kernel
> mappings as no secondary IOMMU implementations can access those and
> hence it is not required.
> 
> [1] - https://lore.kernel.org/all/20230602011518.787006-1-seanjc@google.com/
> [2] - https://lore.kernel.org/linux-mm/ZJMR5bw8l+BbzdJ7@ziepe.ca/
> 
> Alistair Popple (4):
>   mm_notifiers: Rename invalidate_range notifier
>   arm64/smmu: Use TLBI ASID when invalidating entire range
>   mmu_notifiers: Call arch_invalidate_secondary_tlbs() when invalidating TLBs
>   mmu_notifiers: Don't invalidate secondary TLBs as part of mmu_notifier_invalidate_range_end()
> 
>  arch/arm64/include/asm/tlbflush.h               |   5 +-
>  arch/powerpc/include/asm/book3s/64/tlbflush.h   |   1 +-
>  arch/powerpc/mm/book3s64/radix_hugetlbpage.c    |   1 +-
>  arch/powerpc/mm/book3s64/radix_tlb.c            |   6 +-
>  arch/x86/mm/tlb.c                               |   3 +-
>  drivers/iommu/amd/iommu_v2.c                    |  10 +-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c |  29 +++--
>  drivers/iommu/intel/svm.c                       |   8 +-
>  drivers/misc/ocxl/link.c                        |   8 +-
>  include/asm-generic/tlb.h                       |   1 +-
>  include/linux/mmu_notifier.h                    | 104 ++++-------------
>  kernel/events/uprobes.c                         |   2 +-
>  mm/huge_memory.c                                |  29 +----
>  mm/hugetlb.c                                    |   8 +-
>  mm/memory.c                                     |   8 +-
>  mm/migrate_device.c                             |   9 +-
>  mm/mmu_notifier.c                               |  47 +++-----
>  mm/rmap.c                                       |  40 +-------
>  18 files changed, 109 insertions(+), 210 deletions(-)
> 
> base-commit: fdf0eaf11452d72945af31804e2a1048ee1b574c

RE: [PATCH 0/4] Invalidate secondary IOMMU TLB on permission upgrade

[Tian, Kevin]

> From: Anshuman Khandual <anshuman.khandual@arm.com>
> Sent: Wednesday, July 19, 2023 11:04 AM
> 
> On 7/18/23 13:26, Alistair Popple wrote:
> > The main change is to move secondary TLB invalidation mmu notifier
> > callbacks into the architecture specific TLB flushing functions. This
> > makes secondary TLB invalidation mostly match CPU invalidation while
> > still allowing efficient range based invalidations based on the
> > existing TLB batching code.
> >
> > ==========
> > Background
> > ==========
> >
> > The arm64 architecture specifies TLB permission bits may be cached and
> > therefore the TLB must be invalidated during permission upgrades. For
> > the CPU this currently occurs in the architecture specific
> > ptep_set_access_flags() routine.
> >
> > Secondary TLBs such as implemented by the SMMU IOMMU match the CPU
> > architecture specification and may also cache permission bits and
> > require the same TLB invalidations. This may be achieved in one of two
> > ways.
> >
> > Some SMMU implementations implement broadcast TLB maintenance
> > (BTM). This snoops CPU TLB invalidates and will invalidate any
> > secondary TLB at the same time as the CPU. However implementations are
> > not required to implement BTM.
> 
> So, the implementations with BTM do not even need a MMU notifier callback
> for secondary TLB invalidation purpose ? Perhaps mmu_notifier_register()
> could also be skipped for such cases i.e with ARM_SMMU_FEAT_BTM
> enabled ?
> 

Out of curiosity. How does BTM work with device tlb? Can SMMU translate
a TLB broadcast request (based on ASID) into a set of PCI ATS invalidation
requests (based on PCI requestor ID and PASID) in hardware?

If software intervention is required then it might be the reason why mmu
notifier cannot be skipped. With BTM enabled it just means the notifier
callback can skip iotlb invalidation...

Re: [PATCH 0/4] Invalidate secondary IOMMU TLB on permission upgrade

[Alistair Popple]

"Tian, Kevin" <kevin.tian@intel.com> writes:

>> From: Anshuman Khandual <anshuman.khandual@arm.com>
>> Sent: Wednesday, July 19, 2023 11:04 AM
>> 
>> On 7/18/23 13:26, Alistair Popple wrote:
>> > The main change is to move secondary TLB invalidation mmu notifier
>> > callbacks into the architecture specific TLB flushing functions. This
>> > makes secondary TLB invalidation mostly match CPU invalidation while
>> > still allowing efficient range based invalidations based on the
>> > existing TLB batching code.
>> >
>> > ==========
>> > Background
>> > ==========
>> >
>> > The arm64 architecture specifies TLB permission bits may be cached and
>> > therefore the TLB must be invalidated during permission upgrades. For
>> > the CPU this currently occurs in the architecture specific
>> > ptep_set_access_flags() routine.
>> >
>> > Secondary TLBs such as implemented by the SMMU IOMMU match the CPU
>> > architecture specification and may also cache permission bits and
>> > require the same TLB invalidations. This may be achieved in one of two
>> > ways.
>> >
>> > Some SMMU implementations implement broadcast TLB maintenance
>> > (BTM). This snoops CPU TLB invalidates and will invalidate any
>> > secondary TLB at the same time as the CPU. However implementations are
>> > not required to implement BTM.
>> 
>> So, the implementations with BTM do not even need a MMU notifier callback
>> for secondary TLB invalidation purpose ? Perhaps mmu_notifier_register()
>> could also be skipped for such cases i.e with ARM_SMMU_FEAT_BTM
>> enabled ?
>> 

A notifier callback is still required to send the PCIe ATC request to
devices. As I understand it BTM means just that SMMU TLB maintenance
isn't required. In other words SMMU with BTM will snoop CPU TLB
invalidates to maintain the SMMU TLB but still won't generate ATC
requests based on snooping.

> Out of curiosity. How does BTM work with device tlb? Can SMMU translate
> a TLB broadcast request (based on ASID) into a set of PCI ATS invalidation
> requests (based on PCI requestor ID and PASID) in hardware?

See above but I don't think so.

> If software intervention is required then it might be the reason why mmu
> notifier cannot be skipped. With BTM enabled it just means the notifier
> callback can skip iotlb invalidation...

Right. If you look at the implementation for
arm_smmu_mm_arch_invalidate_secondary_tlbs() you can see
arm_smmu_tlb_inv_range_asid() is only called if BTM is not supported to
invalidate SMMU TLB vs. arm_smmu_atc_inv_domain() which is always called
to send the invalidations down to the devices.

>> Based on feedback from Jason [2] the proposed solution to the bug is
>> to move the calls to mmu_notifier_arch_invalidate_secondary_tlbs()
>> closer to the architecture specific TLB invalidation code. This
>> ensures the secondary TLB won't miss invalidations, including the
>> existing invalidation in the ARM64 code to deal with permission
>> upgrade.
>
> ptep_set_access_flags() is the only problematic place where this issue
> is being reported ? If yes, why dont fix that instead of moving these
> into platform specific callbacks ? OR there are other problematic areas
> I might be missing.

See the previous feedback, and in particular this thread -
https://lore.kernel.org/all/5d8e1f752051173d2d1b5c3e14b54eb3506ed3ef.1684892404.git-series.apopple@nvidia.com/.

TLDR - I don't think there are any other problematic areas, but it's
hard to reason about when TLB notifiers should be called when it all
happens out of band and it's easy to miss. For example this bug would
not have been possible had they been called from the TLB flushing code.

Ideally I think most kernel code should call some generic TLB flushing
function that could call this. However at the moment no intermediate
functions exist - kernel calls the architecture specific implementations
directly. Adding a layer of indirection seems like it would be a lot of
churn with possible performance implications as well.