Walk the host page tables to identify hugepage mappings for ZONE_DEVICE pfns, i.e. DAX pages. Explicitly query kvm_is_zone_device_pfn() when deciding whether or not to bother walking the host page tables, as DAX pages do not set up the head/tail infrastructure, i.e. will return false for PageCompound() even when using huge pages.
Zap ZONE_DEVICE sptes when disabling dirty logging, e.g. if live migration fails, to allow KVM to rebuild large pages for DAX-based mappings. Presumably DAX favors large pages, and worst case scenario is a minor performance hit as KVM will need to re-fault all DAX-based pages. Suggested-by: Barret Rhoden <[email protected]> Cc: David Hildenbrand <[email protected]> Cc: Dan Williams <[email protected]> Cc: Jason Zeng <[email protected]> Cc: Dave Jiang <[email protected]> Cc: Liran Alon <[email protected]> Cc: linux-nvdimm <[email protected]> Signed-off-by: Sean Christopherson <[email protected]> --- arch/x86/kvm/mmu/mmu.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 1e4e0ac169a7..324e1919722f 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3250,7 +3250,7 @@ static int host_pfn_mapping_level(struct kvm_vcpu *vcpu, gfn_t gfn, PT_DIRECTORY_LEVEL != (int)PG_LEVEL_2M || PT_PDPE_LEVEL != (int)PG_LEVEL_1G); - if (!PageCompound(pfn_to_page(pfn))) + if (!PageCompound(pfn_to_page(pfn)) && !kvm_is_zone_device_pfn(pfn)) return PT_PAGE_TABLE_LEVEL; /* @@ -3282,8 +3282,7 @@ static int kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t gfn, if (unlikely(max_level == PT_PAGE_TABLE_LEVEL)) return PT_PAGE_TABLE_LEVEL; - if (is_error_noslot_pfn(pfn) || kvm_is_reserved_pfn(pfn) || - kvm_is_zone_device_pfn(pfn)) + if (is_error_noslot_pfn(pfn) || kvm_is_reserved_pfn(pfn)) return PT_PAGE_TABLE_LEVEL; slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); @@ -5910,8 +5909,8 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, * mapping if the indirect sp has level = 1. */ if (sp->role.direct && !kvm_is_reserved_pfn(pfn) && - !kvm_is_zone_device_pfn(pfn) && - PageCompound(pfn_to_page(pfn))) { + (kvm_is_zone_device_pfn(pfn) || + PageCompound(pfn_to_page(pfn)))) { pte_list_remove(rmap_head, sptep); if (kvm_available_flush_tlb_with_range()) -- 2.24.1 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
