[PATCH] KVM: nVMX: Add VM-Enter failed tracepoints for super early checks

From: Sean Christopherson
Date: Wed Aug 12 2020 - 14:06:19 EST


Add tracepoints for the early consistency checks in nested_vmx_run().
The "VMLAUNCH vs. VMRESUME" check in particular is useful to trace, as
there is no architectural way to check VMCS.LAUNCH_STATE, and subtle
bugs such as VMCLEAR on the wrong HPA can lead to confusing errors in
the L1 VMM.

Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 23b58c28a1c92..fb37f0972e78a 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3468,11 +3468,11 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
if (evmptrld_status == EVMPTRLD_ERROR) {
kvm_queue_exception(vcpu, UD_VECTOR);
return 1;
- } else if (evmptrld_status == EVMPTRLD_VMFAIL) {
+ } else if (CC(evmptrld_status == EVMPTRLD_VMFAIL)) {
return nested_vmx_failInvalid(vcpu);
}

- if (!vmx->nested.hv_evmcs && vmx->nested.current_vmptr == -1ull)
+ if (CC(!vmx->nested.hv_evmcs && vmx->nested.current_vmptr == -1ull))
return nested_vmx_failInvalid(vcpu);

vmcs12 = get_vmcs12(vcpu);
@@ -3483,7 +3483,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
* rather than RFLAGS.ZF, and no error number is stored to the
* VM-instruction error field.
*/
- if (vmcs12->hdr.shadow_vmcs)
+ if (CC(vmcs12->hdr.shadow_vmcs))
return nested_vmx_failInvalid(vcpu);

if (vmx->nested.hv_evmcs) {
@@ -3504,10 +3504,10 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
* for misconfigurations which will anyway be caught by the processor
* when using the merged vmcs02.
*/
- if (interrupt_shadow & KVM_X86_SHADOW_INT_MOV_SS)
+ if (CC(interrupt_shadow & KVM_X86_SHADOW_INT_MOV_SS))
return nested_vmx_fail(vcpu, VMXERR_ENTRY_EVENTS_BLOCKED_BY_MOV_SS);

- if (vmcs12->launch_state == launch)
+ if (CC(vmcs12->launch_state == launch))
return nested_vmx_fail(vcpu,
launch ? VMXERR_VMLAUNCH_NONCLEAR_VMCS
: VMXERR_VMRESUME_NONLAUNCHED_VMCS);
--
2.28.0