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Subject[PATCH 12/12] KVM: nSVM: Trace VM-Enter consistency check failures
From
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@google.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
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