The AMD APM states that if VMMCALL instruction is not intercepted, the
instruction raises a #UD exception.
Create a vmmcall exit handler that generates a #UD if a VMMCALL exit
from L2 is being handled by L0, which means that L1 did not intercept
the VMMCALL instruction.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Kevin Cheng <chengkev@google.com>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Reviewed-by: Manali Shukla <manali.shukla@amd.com>
Tested-by: Manali Shukla <manali.shukla@amd.com>
---
arch/x86/kvm/svm/svm.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 1888211e20988..9257976ded539 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3194,6 +3194,20 @@ static int bus_lock_exit(struct kvm_vcpu *vcpu)
return 0;
}
+static int vmmcall_interception(struct kvm_vcpu *vcpu)
+{
+ /*
+ * VMMCALL #UDs if it's not intercepted, and KVM reaches this point if
+ * and only if the VMMCALL intercept is not set in vmcb12.
+ */
+ if (is_guest_mode(vcpu)) {
+ kvm_queue_exception(vcpu, UD_VECTOR);
+ return 1;
+ }
+
+ return kvm_emulate_hypercall(vcpu);
+}
+
static int (*const svm_exit_handlers[])(struct kvm_vcpu *vcpu) = {
[SVM_EXIT_READ_CR0] = cr_interception,
[SVM_EXIT_READ_CR3] = cr_interception,
@@ -3244,7 +3258,7 @@ static int (*const svm_exit_handlers[])(struct kvm_vcpu *vcpu) = {
[SVM_EXIT_TASK_SWITCH] = task_switch_interception,
[SVM_EXIT_SHUTDOWN] = shutdown_interception,
[SVM_EXIT_VMRUN] = vmrun_interception,
- [SVM_EXIT_VMMCALL] = kvm_emulate_hypercall,
+ [SVM_EXIT_VMMCALL] = vmmcall_interception,
[SVM_EXIT_VMLOAD] = vmload_interception,
[SVM_EXIT_VMSAVE] = vmsave_interception,
[SVM_EXIT_STGI] = stgi_interception,
--
2.52.0.457.g6b5491de43-goog