[PATCH] tlb: hugetlb: Add arm64 contiguous hint awareness

[Steve Capper <steve.capper@arm.com>]

tlb_remove_huge_tlb_entry only considers PMD_SIZE and PUD_SIZE when
updating the mmu_gather structure.

Unfortunately on arm64 there are two additional huge page sizes that
need to be covered: CONT_PTE_SIZE and CONT_PMD_SIZE. Where an end-user
attempts to employ contiguous huge pages, a VM_BUG_ON can be experienced
due to the fact that the tlb structure hasn't been correctly updated by
the relevant tlb_flush_p.._range() call from tlb_remove_huge_tlb_entry.

This patch adds the ability to define per-arch implementations of
tlb_remove_huge_tlb_entry and supplies an arm64 implementation that
covers the contiguous hint sizes.

Reported-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/linux-mm/811c5c8e-b3a2-85d2-049c-717f17c3a03a@redhat.com/
Signed-off-by: Steve Capper <steve.capper@arm.com>
---
 arch/arm64/include/asm/tlb.h | 14 ++++++++++++++
 include/asm-generic/tlb.h    |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
index c995d1f4594f..311d201d4e72 100644
--- a/arch/arm64/include/asm/tlb.h
+++ b/arch/arm64/include/asm/tlb.h
@@ -19,6 +19,20 @@ static inline void __tlb_remove_table(void *_table)
 #define tlb_flush tlb_flush
 static void tlb_flush(struct mmu_gather *tlb);
 
+#define tlb_remove_huge_tlb_entry(h, tlb, ptep, address)	\
+	do {							\
+		unsigned long _sz = huge_page_size(h);		\
+		if (_sz == CONT_PTE_SIZE)			\
+			tlb_flush_pte_range(tlb, address, _sz);	\
+		else if (_sz == PMD_SIZE)			\
+			tlb_flush_pmd_range(tlb, address, _sz);	\
+		else if (_sz == CONT_PMD_SIZE)			\
+			tlb_flush_pmd_range(tlb, address, _sz);	\
+		else if (_sz == PUD_SIZE)			\
+			tlb_flush_pud_range(tlb, address, _sz);	\
+		__tlb_remove_tlb_entry(tlb, ptep, address);	\
+	} while (0)
+
 #include <asm-generic/tlb.h>
 
 /*
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 2c68a545ffa7..4622ee45f739 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -562,6 +562,7 @@ static inline void tlb_flush_p4d_range(struct mmu_gather *tlb,
 		__tlb_remove_tlb_entry(tlb, ptep, address);	\
 	} while (0)
 
+#ifndef tlb_remove_huge_tlb_entry
 #define tlb_remove_huge_tlb_entry(h, tlb, ptep, address)	\
 	do {							\
 		unsigned long _sz = huge_page_size(h);		\
@@ -571,6 +572,7 @@ static inline void tlb_flush_p4d_range(struct mmu_gather *tlb,
 			tlb_flush_pud_range(tlb, address, _sz);	\
 		__tlb_remove_tlb_entry(tlb, ptep, address);	\
 	} while (0)
+#endif
 
 /**
  * tlb_remove_pmd_tlb_entry - remember a pmd mapping for later tlb invalidation
-- 
2.35.1