[PATCH v12 28/77] KVM: x86: disable gpa_available optimization for fetch and page-walk SPT violations
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STALE1836d
From: Adalbert Lazăr <hidden>
Date: 2021-10-06 17:40:42
Also in:
kvm
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Revision v12 of 7 in this series.
Revisions (7)
From: Mircea Cîrjaliu <redacted> This change is needed because the introspection tool can write-protect guest page tables or exec-protect heap/stack pages. Signed-off-by: Mircea Cîrjaliu <redacted> Co-developed-by: Adalbert Lazăr <redacted> Signed-off-by: Adalbert Lazăr <redacted> --- arch/x86/include/asm/kvm_host.h | 5 +++++ arch/x86/kvm/mmu/mmu.c | 7 +++++++ arch/x86/kvm/x86.c | 2 +- 3 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 692e55a5c312..dc3c83edc4bc 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h@@ -1664,6 +1664,10 @@ extern u64 kvm_mce_cap_supported; * retry native execution under certain conditions, * Can only be set in conjunction with EMULTYPE_PF. * + * EMULTYPE_GPA_AVAILABLE_PF - Set when the emulator can avoid a page walk + * to get the GPA. + * Can only be set in conjunction with EMULTYPE_PF. + * * EMULTYPE_TRAP_UD_FORCED - Set when emulating an intercepted #UD that was * triggered by KVM's magic "force emulation" prefix, * which is opt in via module param (off by default).
@@ -1686,6 +1690,7 @@ extern u64 kvm_mce_cap_supported; #define EMULTYPE_TRAP_UD_FORCED (1 << 4) #define EMULTYPE_VMWARE_GP (1 << 5) #define EMULTYPE_PF (1 << 6) +#define EMULTYPE_GPA_AVAILABLE_PF (1 << 7) int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type); int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index b5685e342945..c90683284098 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c@@ -5297,6 +5297,13 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa))) return RET_PF_RETRY; + /* + * With shadow page tables, fault_address contains a GVA or nGPA. + * On a fetch fault, fault_address contains the instruction pointer. + */ + if (direct && likely(!(error_code & PFERR_FETCH_MASK)) && + (error_code & PFERR_GUEST_FINAL_MASK)) + emulation_type |= EMULTYPE_GPA_AVAILABLE_PF; r = RET_PF_INVALID; if (unlikely(error_code & PFERR_RSVD_MASK)) {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c52ac5e9a020..ab97e0175c04 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c@@ -7933,7 +7933,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, ctxt->exception.address = cr2_or_gpa; /* With shadow page tables, cr2 contains a GVA or nGPA. */ - if (vcpu->arch.mmu->direct_map) { + if (emulation_type & EMULTYPE_GPA_AVAILABLE_PF) { ctxt->gpa_available = true; ctxt->gpa_val = cr2_or_gpa; }
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