From 694556d54f354d3fe43bb2e61fd6103cca2638a4 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 23 Aug 2018 09:58:27 +0100 Subject: KVM: arm/arm64: Clean dcache to PoC when changing PTE due to CoW When triggering a CoW, we unmap the RO page via an MMU notifier (invalidate_range_start), and then populate the new PTE using another one (change_pte). In the meantime, we'll have copied the old page into the new one. The problem is that the data for the new page is sitting in the cache, and should the guest have an uncached mapping to that page (or its MMU off), following accesses will bypass the cache. In a way, this is similar to what happens on a translation fault: We need to clean the page to the PoC before mapping it. So let's just do that. This fixes a KVM unit test regression observed on a HiSilicon platform, and subsequently reproduced on Seattle. Fixes: a9c0e12ebee5 ("KVM: arm/arm64: Only clean the dcache on translation fault") Cc: stable@vger.kernel.org # v4.16+ Reported-by: Mike Galbraith Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall --- virt/kvm/arm/mmu.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'virt/kvm') diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c index 91aaf73b00df..111a660be3be 100644 --- a/virt/kvm/arm/mmu.c +++ b/virt/kvm/arm/mmu.c @@ -1860,13 +1860,20 @@ static int kvm_set_spte_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte) { unsigned long end = hva + PAGE_SIZE; + kvm_pfn_t pfn = pte_pfn(pte); pte_t stage2_pte; if (!kvm->arch.pgd) return; trace_kvm_set_spte_hva(hva); - stage2_pte = pfn_pte(pte_pfn(pte), PAGE_S2); + + /* + * We've moved a page around, probably through CoW, so let's treat it + * just like a translation fault and clean the cache to the PoC. + */ + clean_dcache_guest_page(pfn, PAGE_SIZE); + stage2_pte = pfn_pte(pfn, PAGE_S2); handle_hva_to_gpa(kvm, hva, end, &kvm_set_spte_handler, &stage2_pte); } -- cgit v1.2.3-70-g09d2 From a35381e10dc46dd75e65e4b3832d9a0005d48d44 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 23 Aug 2018 10:18:14 +0100 Subject: KVM: Remove obsolete kvm_unmap_hva notifier backend kvm_unmap_hva is long gone, and we only have kvm_unmap_hva_range to deal with. Drop the now obsolete code. Fixes: fb1522e099f0 ("KVM: update to new mmu_notifier semantic v2") Cc: James Hogan Reviewed-by: Paolo Bonzini Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall --- arch/arm/include/asm/kvm_host.h | 1 - arch/arm64/include/asm/kvm_host.h | 1 - arch/mips/include/asm/kvm_host.h | 1 - arch/mips/kvm/mmu.c | 10 ---------- arch/x86/include/asm/kvm_host.h | 1 - arch/x86/kvm/mmu.c | 5 ----- virt/kvm/arm/mmu.c | 12 ------------ virt/kvm/arm/trace.h | 15 --------------- 8 files changed, 46 deletions(-) (limited to 'virt/kvm') diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index 79906cecb091..3ad482d2f1eb 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -223,7 +223,6 @@ int __kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu, struct kvm_vcpu_events *events); #define KVM_ARCH_WANT_MMU_NOTIFIER -int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end); void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte); diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index f26055f2306e..8e6d46df38aa 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -357,7 +357,6 @@ int __kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu, struct kvm_vcpu_events *events); #define KVM_ARCH_WANT_MMU_NOTIFIER -int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end); void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte); diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h index a9af1d2dcd69..2c1c53d12179 100644 --- a/arch/mips/include/asm/kvm_host.h +++ b/arch/mips/include/asm/kvm_host.h @@ -931,7 +931,6 @@ enum kvm_mips_fault_result kvm_trap_emul_gva_fault(struct kvm_vcpu *vcpu, bool write); #define KVM_ARCH_WANT_MMU_NOTIFIER -int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end); void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte); diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c index ee64db032793..d8dcdb350405 100644 --- a/arch/mips/kvm/mmu.c +++ b/arch/mips/kvm/mmu.c @@ -512,16 +512,6 @@ static int kvm_unmap_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end, return 1; } -int kvm_unmap_hva(struct kvm *kvm, unsigned long hva) -{ - unsigned long end = hva + PAGE_SIZE; - - handle_hva_to_gpa(kvm, hva, end, &kvm_unmap_hva_handler, NULL); - - kvm_mips_callbacks->flush_shadow_all(kvm); - return 0; -} - int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end) { handle_hva_to_gpa(kvm, start, end, &kvm_unmap_hva_handler, NULL); diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 00ddb0c9e612..e6a33420b871 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1450,7 +1450,6 @@ asmlinkage void kvm_spurious_fault(void); ____kvm_handle_fault_on_reboot(insn, "") #define KVM_ARCH_WANT_MMU_NOTIFIER -int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end); int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end); int kvm_test_age_hva(struct kvm *kvm, unsigned long hva); diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index a282321329b5..d440154e8938 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1853,11 +1853,6 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva, return kvm_handle_hva_range(kvm, hva, hva + 1, data, handler); } -int kvm_unmap_hva(struct kvm *kvm, unsigned long hva) -{ - return kvm_handle_hva(kvm, hva, 0, kvm_unmap_rmapp); -} - int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end) { return kvm_handle_hva_range(kvm, start, end, 0, kvm_unmap_rmapp); diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c index 111a660be3be..ed162a6c57c5 100644 --- a/virt/kvm/arm/mmu.c +++ b/virt/kvm/arm/mmu.c @@ -1817,18 +1817,6 @@ static int kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *dat return 0; } -int kvm_unmap_hva(struct kvm *kvm, unsigned long hva) -{ - unsigned long end = hva + PAGE_SIZE; - - if (!kvm->arch.pgd) - return 0; - - trace_kvm_unmap_hva(hva); - handle_hva_to_gpa(kvm, hva, end, &kvm_unmap_hva_handler, NULL); - return 0; -} - int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end) { diff --git a/virt/kvm/arm/trace.h b/virt/kvm/arm/trace.h index e53b596f483b..57b3edebbb40 100644 --- a/virt/kvm/arm/trace.h +++ b/virt/kvm/arm/trace.h @@ -134,21 +134,6 @@ TRACE_EVENT(kvm_mmio_emulate, __entry->vcpu_pc, __entry->instr, __entry->cpsr) ); -TRACE_EVENT(kvm_unmap_hva, - TP_PROTO(unsigned long hva), - TP_ARGS(hva), - - TP_STRUCT__entry( - __field( unsigned long, hva ) - ), - - TP_fast_assign( - __entry->hva = hva; - ), - - TP_printk("mmu notifier unmap hva: %#08lx", __entry->hva) -); - TRACE_EVENT(kvm_unmap_hva_range, TP_PROTO(unsigned long start, unsigned long end), TP_ARGS(start, end), -- cgit v1.2.3-70-g09d2