Michael Ellerman <mpe@xxxxxxxxxxxxxx> writes: > Alistair Popple <apopple@xxxxxxxxxx> 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 >> arahitecutre specific ptep_set_access_flags() which calls > ^ > architecture Oh. I'd forgotten to apt install codespell ;-) >> 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@xxxxxxxxxx> >> Suggested-by: Jason Gunthorpe <jgg@xxxxxxxx> >> > ... > >> 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. I suspect you're correct. It's been a while since I last worked on PPC TLB invalidation code though and it's changed a fair bit since then so was being conservative and appreciate any comments there. Was worried I may have missed some clever optimisation that detects a local flush is all that's needed, but I see OCXL calls mm_context_add_copro() though so that should be ok. Will respin and drop it. > cheers
