[v10,19/81] KVM: x86: save the error code during EPT/NPF exits handling

Commit Message

Adalbert Lazăr Nov. 25, 2020, 9:34 a.m. UTC

From: Mihai Donțu <[e-mail]>

This is needed for kvm_page_track_emulation_failure().

When the introspection tool {read,write,exec}-protect a guest memory
page, it is notified from the read/write/fetch callbacks used by
the KVM emulator. If the emulation fails it is possible that the
read/write callbacks were not used. In such cases, the emulator will
call kvm_page_track_emulation_failure() to ensure that the introspection
tool is notified of the read/write #PF (based on this saved error code),
which in turn can emulate the instruction or unprotect the memory page
(and let the guest execute the instruction).

Signed-off-by: Mihai Donțu <[e-mail]>
Signed-off-by: Adalbert Lazăr <[e-mail]>
---
 arch/x86/include/asm/kvm_host.h | 3 +++
 arch/x86/kvm/svm/svm.c          | 2 ++
 arch/x86/kvm/vmx/vmx.c          | 1 +
 3 files changed, 6 insertions(+)

Patch

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 01853453a659..86048037da23 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -813,6 +813,9 @@  struct kvm_vcpu_arch {
 		 */
 		bool enforce;
 	} pv_cpuid;
+
+	/* #PF translated error code from EPT/NPT exit reason */
+	u64 error_code;
 };
 
 struct kvm_lpage_info {
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 2bfefcfbddd7..43a2e4ec6178 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1916,6 +1916,8 @@  static int npf_interception(struct vcpu_svm *svm)
 	u64 fault_address = __sme_clr(svm->vmcb->control.exit_info_2);
 	u64 error_code = svm->vmcb->control.exit_info_1;
 
+	svm->vcpu.arch.error_code = error_code;
+
 	trace_kvm_page_fault(fault_address, error_code);
 	return kvm_mmu_page_fault(&svm->vcpu, fault_address, error_code,
 			static_cpu_has(X86_FEATURE_DECODEASSISTS) ?
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a7d2bab38233..d5d4203378d3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5390,6 +5390,7 @@  static int handle_ept_violation(struct kvm_vcpu *vcpu)
 		      ? PFERR_GUEST_FINAL_MASK : PFERR_GUEST_PAGE_MASK;
 
 	vcpu->arch.exit_qualification = exit_qualification;
+	vcpu->arch.error_code = error_code;
 
 	/*
 	 * Check that the GPA doesn't exceed physical memory limits, as that is