Re: [PATCH v11 09/35] KVM: x86: Determine shared/private faults based on vm_type
From: Paolo Bonzini <pbonzini@redhat.com>
Date: 2024-02-12 10:31:41
Also in:
kvm, linux-coco, lkml
On Sat, Dec 30, 2023 at 6:24 PM Michael Roth [off-list ref] wrote:
quoted hunk ↗ jump to hunk
For KVM_X86_SNP_VM, only the PFERR_GUEST_ENC_MASK flag is needed to determine with an #NPF is due to a private/shared access by the guest. Implement that handling here. Also add handling needed to deal with SNP guests which in some cases will make MMIO accesses with the encryption bit. Signed-off-by: Michael Roth <redacted> --- arch/x86/kvm/mmu/mmu.c | 12 ++++++++++-- arch/x86/kvm/mmu/mmu_internal.h | 20 +++++++++++++++++++- 2 files changed, 29 insertions(+), 3 deletions(-)diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index d3fbfe0686a0..61213f6648a1 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c@@ -4331,6 +4331,7 @@ static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { struct kvm_memory_slot *slot = fault->slot; + bool private_fault = fault->is_private;
I think it's nicer to just make the fault !is_private in kvm_mmu_do_page_fault().
+static bool kvm_mmu_fault_is_private(struct kvm *kvm, gpa_t gpa, u64 err)
+{
+ bool private_fault = false;
+
+ if (kvm_is_vm_type(kvm, KVM_X86_SNP_VM)) {
+ private_fault = !!(err & PFERR_GUEST_ENC_MASK);
+ } else if (kvm_is_vm_type(kvm, KVM_X86_SW_PROTECTED_VM)) {
+ /*
+ * This handling is for gmem self-tests and guests that treat
+ * userspace as the authority on whether a fault should be
+ * private or not.
+ */
+ private_fault = kvm_mem_is_private(kvm, gpa >> PAGE_SHIFT);
+ }Any reason to remove the is_private page fault that was there in previous versions of the patch? I don't really like having both TDX and SVM-specific code in this function. Paolo
quoted hunk ↗ jump to hunk
+ return private_fault; +} + /* * Return values of handle_mmio_page_fault(), mmu.page_fault(), fast_page_fault(), * and of course kvm_mmu_do_page_fault().@@ -298,7 +316,7 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, .max_level = KVM_MAX_HUGEPAGE_LEVEL, .req_level = PG_LEVEL_4K, .goal_level = PG_LEVEL_4K, - .is_private = kvm_mem_is_private(vcpu->kvm, cr2_or_gpa >> PAGE_SHIFT), + .is_private = kvm_mmu_fault_is_private(vcpu->kvm, cr2_or_gpa, err), }; int r; --2.25.1