linux-kernel - [PATCH 12/12] KVM: nSVM: Trace VM-Enter consistency check failures

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Message-Id: <20210204000117.3303214-13-seanjc@google.com>
Date:   Wed,  3 Feb 2021 16:01:17 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Tom Lendacky <thomas.lendacky@....com>,
        Brijesh Singh <brijesh.singh@....com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>
Subject: [PATCH 12/12] KVM: nSVM: Trace VM-Enter consistency check failures

Use trace_kvm_nested_vmenter_failed() and its macro magic to trace
consistency check failures on nested VMRUN.  Tracing such failures by
running the buggy VMM as a KVM guest is often the only way to get a
precise explanation of why VMRUN failed.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/nested.c | 33 +++++++++++++++++++--------------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index add3cd4295e1..16fea02471a7 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -29,6 +29,8 @@
 #include "lapic.h"
 #include "svm.h"
 
+#define CC KVM_NESTED_VMENTER_CONSISTENCY_CHECK
+
 static void nested_svm_inject_npf_exit(struct kvm_vcpu *vcpu,
 				       struct x86_exception *fault)
 {
@@ -216,14 +218,13 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu)
 
 static bool nested_vmcb_check_controls(struct vmcb_control_area *control)
 {
-	if ((vmcb_is_intercept(control, INTERCEPT_VMRUN)) == 0)
+	if (CC(!vmcb_is_intercept(control, INTERCEPT_VMRUN)))
 		return false;
 
-	if (control->asid == 0)
+	if (CC(control->asid == 0))
 		return false;
 
-	if ((control->nested_ctl & SVM_NESTED_CTL_NP_ENABLE) &&
-	    !npt_enabled)
+	if (CC((control->nested_ctl & SVM_NESTED_CTL_NP_ENABLE) && !npt_enabled))
 		return false;
 
 	return true;
@@ -240,32 +241,36 @@ static bool nested_vmcb_check_cr3_cr4(struct vcpu_svm *svm,
 	 * CR0.PG && EFER.LME.
 	 */
 	if ((save->efer & EFER_LME) && (save->cr0 & X86_CR0_PG)) {
-		if (!(save->cr4 & X86_CR4_PAE) || !(save->cr0 & X86_CR0_PE) ||
-		    kvm_vcpu_is_illegal_gpa(vcpu, save->cr3))
+		if (CC(!(save->cr4 & X86_CR4_PAE)) ||
+		    CC(!(save->cr0 & X86_CR0_PE)) ||
+		    CC(kvm_vcpu_is_illegal_gpa(vcpu, save->cr3)))
 			return false;
 	}
 
-	return kvm_is_valid_cr4(&svm->vcpu, save->cr4);
+	if (CC(!kvm_is_valid_cr4(vcpu, save->cr4)))
+		return false;
+
+	return true;
 }
 
 /* Common checks that apply to both L1 and L2 state.  */
 static bool nested_vmcb_valid_sregs(struct vcpu_svm *svm,
 				    struct vmcb_save_area *save)
 {
-	if (!(save->efer & EFER_SVME))
+	if (CC(!(save->efer & EFER_SVME)))
 		return false;
 
-	if (((save->cr0 & X86_CR0_CD) == 0 && (save->cr0 & X86_CR0_NW)) ||
-	    (save->cr0 & ~0xffffffffULL))
+	if (CC((save->cr0 & X86_CR0_CD) == 0 && (save->cr0 & X86_CR0_NW)) ||
+	    CC(save->cr0 & ~0xffffffffULL))
 		return false;
 
-	if (!kvm_dr6_valid(save->dr6) || !kvm_dr7_valid(save->dr7))
+	if (CC(!kvm_dr6_valid(save->dr6)) || CC(!kvm_dr7_valid(save->dr7)))
 		return false;
 
 	if (!nested_vmcb_check_cr3_cr4(svm, save))
 		return false;
 
-	if (!kvm_valid_efer(&svm->vcpu, save->efer))
+	if (CC(!kvm_valid_efer(&svm->vcpu, save->efer)))
 		return false;
 
 	return true;
@@ -367,12 +372,12 @@ static inline bool nested_npt_enabled(struct vcpu_svm *svm)
 static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
 			       bool nested_npt)
 {
-	if (kvm_vcpu_is_illegal_gpa(vcpu, cr3))
+	if (CC(kvm_vcpu_is_illegal_gpa(vcpu, cr3)))
 		return -EINVAL;
 
 	if (!nested_npt && is_pae_paging(vcpu) &&
 	    (cr3 != kvm_read_cr3(vcpu) || pdptrs_changed(vcpu))) {
-		if (!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
+		if (CC(!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3)))
 			return -EINVAL;
 	}
 
-- 
2.30.0.365.g02bc693789-goog