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Tue, 25 Jul 2023 13:42:00 +1000 (AEST) From: Michael Ellerman To: Alistair Popple , akpm@linux-foundation.org Cc: ajd@linux.ibm.com, catalin.marinas@arm.com, fbarrat@linux.ibm.com, iommu@lists.linux.dev, jgg@ziepe.ca, jhubbard@nvidia.com, kevin.tian@intel.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, nicolinc@nvidia.com, npiggin@gmail.com, robin.murphy@arm.com, seanjc@google.com, will@kernel.org, x86@kernel.org, zhi.wang.linux@gmail.com, Alistair Popple Subject: Re: [PATCH v2 3/5] mmu_notifiers: Call invalidate_range() when invalidating TLBs In-Reply-To: <8f293bb51a423afa71ddc3ba46e9f323ee9ffbc7.1689768831.git-series.apopple@nvidia.com> References: <8f293bb51a423afa71ddc3ba46e9f323ee9ffbc7.1689768831.git-series.apopple@nvidia.com> Date: Tue, 25 Jul 2023 13:41:59 +1000 Message-ID: <87y1j4y7w8.fsf@mail.lhotse> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 94D73C000D X-Stat-Signature: irhsft4c4aq7eejf5nstwzwiw4tnfr6r X-Rspam-User: X-HE-Tag: 1690256524-587761 X-HE-Meta: U2FsdGVkX1+p8knLsM48nq8GtEYIq/3IGAUR60K7hyZmS1TSEKzZ8mFE18u+z13MNMrgp0RojsbUh1IBDs7lDB8bjCrRu2lvwhxgl00+rV6xde4qFXlM2G6EaeDL7Aq/hTL8fCiFT+D+Z8uthrc60msu74dDZfAw1LPwXq0BMu3ZpUiorzdnAxDoXp2G0+4R77OQwg37DBV24lKi5OtZt8wU18dW9ftYjSe/B8JaC2x6PUPAqpbeDXqhh2KUaXzai/J7DbSTP9pUY8ZJTWWXGoEDY/A6l4UTzbKNsdxUbZnjo13fVtBFGKxFRp5BKD06D1ZbTFc2NUsozjz7V0iSQgIzskXWxCSiMm0DvXwzJaEhVKLd526yvdJx/gdoGEdhHqAV6xJ/XVIhc+3lFAUcmlFCk0dEYJvHgMj4zFPPjLufs5wXs1Jtl5rhRnS/5xI/gjcvAOp+3jE0mQcglOrnc/zTzv79V0xrsF2OCDCN1IDRmpmQUEDumUsJb915+50g/MKZt+YW2ypCQjyIXHpKwzGdD0HBuCm9dPKfo74fN2997hK4QXoV8gatCOueNv5alDHO5sasK+FmgN8eQGkJoXoQY8QO4voJWSw8jS5oD+wDKbtQN7E6IRZNDRInWprypGsQV9EnkgdZUciCWBjOb++pmoP5FUgcKzzuOzJb6nDnkQ7krzRJTZTRZJ31Lz58TLuton3HWIMPkT4zX5wOmO7HXMm8402EQYRcmwPhIdonN6Qy70uI5El18mOnKZysuj3mJLY0qrvSANQ338f5I7bEQPHvbmXOI9zDMC3fIxNnm7WZWNE2xyx55aavNONLguILSZk8jekQpD1Jc9ABWHFyZCp0ar+KtPTYuNX7ZVNq3kq1Dbpkvtoy6ZP50du+gY498Wcmwdnetr1RFuj6rmXJPI4jh6oK3Q9TCXZcTpmvYxE3lidTmWC0CVpoIzsZL0J9c+8/upZxJnSQQsr nVJV4VJ3 6y/EF+6VHOBVHzNaIYGyaPDVke7yliZfksHqDDTnwZv49e4JDRVdtnWopEHogQYB4abWBqgLfXuD8/WFCK0hg+ADEE5Ox+xfhLPD9o02PhjEOb9vOqIDoCbnYyq2Ys3ZWSpqrbPDM99NUTV+wn6zgMryt8FTuy1Uk87k3HmwMWUH9JMLmAuQbC5M3lZKYDJ3ceELUjWV0yy8XgWB+vV9ritXHngCdHrayeyMmJET30ZMd1JtZviZoIUM0K2QXkHUxKTiIb5Bp3KTZpgPg5JnZ1dbxhSKZyC8G6bTV X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Alistair Popple writes: > The invalidate_range() is going to become 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 ^ architecture > 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 > Suggested-by: Jason Gunthorpe > ... > diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c > index 0bd4866..9724b26 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_invalidate_range(vma->vm_mm, vmaddr, > + vmaddr + mmu_virtual_psize); > } > EXPORT_SYMBOL(radix__local_flush_tlb_page); I think we can skip calling the notifier there? It's explicitly a local flush. cheers