From 425333bf3a7743715c17e503049d0837d6c4a603 Mon Sep 17 00:00:00 2001 From: Alexey Kardashevskiy Date: Mon, 10 Sep 2018 18:29:07 +1000 Subject: KVM: PPC: Avoid marking DMA-mapped pages dirty in real mode At the moment the real mode handler of H_PUT_TCE calls iommu_tce_xchg_rm() which in turn reads the old TCE and if it was a valid entry, marks the physical page dirty if it was mapped for writing. Since it is in real mode, realmode_pfn_to_page() is used instead of pfn_to_page() to get the page struct. However SetPageDirty() itself reads the compound page head and returns a virtual address for the head page struct and setting dirty bit for that kills the system. This adds additional dirty bit tracking into the MM/IOMMU API for use in the real mode. Note that this does not change how VFIO and KVM (in virtual mode) set this bit. The KVM (real mode) changes include: - use the lowest bit of the cached host phys address to carry the dirty bit; - mark pages dirty when they are unpinned which happens when the preregistered memory is released which always happens in virtual mode; - add mm_iommu_ua_mark_dirty_rm() helper to set delayed dirty bit; - change iommu_tce_xchg_rm() to take the kvm struct for the mm to use in the new mm_iommu_ua_mark_dirty_rm() helper; - move iommu_tce_xchg_rm() to book3s_64_vio_hv.c (which is the only caller anyway) to reduce the real mode KVM and IOMMU knowledge across different subsystems. This removes realmode_pfn_to_page() as it is not used anymore. While we at it, remove some EXPORT_SYMBOL_GPL() as that code is for the real mode only and modules cannot call it anyway. Signed-off-by: Alexey Kardashevskiy Reviewed-by: David Gibson Signed-off-by: Paul Mackerras --- arch/powerpc/include/asm/mmu_context.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/powerpc/include/asm/mmu_context.h') diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h index b2f89b621b15..b694d6af1150 100644 --- a/arch/powerpc/include/asm/mmu_context.h +++ b/arch/powerpc/include/asm/mmu_context.h @@ -38,6 +38,7 @@ extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem, unsigned long ua, unsigned int pageshift, unsigned long *hpa); extern long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem, unsigned long ua, unsigned int pageshift, unsigned long *hpa); +extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua); extern long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem); extern void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem); #endif -- cgit v1.2.3