WARN and inject #UD when emulating VMFUNC for L2 if the function is
out-of-bounds or if VMFUNC is not enabled in vmcs12. Neither condition
should occur in practice, as the CPU is supposed to prioritize the #UD
over VM-Exit for out-of-bounds input and KVM is supposed to enable
VMFUNC in vmcs02 if and only if it's enabled in vmcs12, but neither of
those dependencies is obvious.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index f686618d9ede..0075d3f0f8fa 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5494,6 +5494,16 @@ static int handle_vmfunc(struct kvm_vcpu *vcpu)
}
vmcs12 = get_vmcs12(vcpu);
+
+ /*
+ * #UD on out-of-bounds function has priority over VM-Exit, and VMFUNC
+ * is enabled in vmcs02 if and only if it's enabled in vmcs12.
+ */
+ if (WARN_ON_ONCE((function > 63) || !nested_cpu_has_vmfunc(vmcs12))) {
+ kvm_queue_exception(vcpu, UD_VECTOR);
+ return 1;
+ }
+
if (!(vmcs12->vm_function_control & BIT_ULL(function)))
goto fail;
--
2.32.0.rc1.229.g3e70b5a671-goog
