[PATCH] KVM: SEV: Update SEV-ES shutdown intercepts with more metadata

Peter Gonda
2023-09-05T17:09:00Z

Currently if an SEV-ES VM shuts down userspace sees KVM_RUN struct with
only the INVALID_ARGUMENT. This is a very limited amount of information
to debug the situation. Instead KVM can return a
KVM_SYSTEM_EVENT_SEV_TERM to alert userspace the VM is shutting down and
is not usable any further. This latter point can be enforced using the
kvm_vm_dead() functionality.

Signed-off-by: Peter Gonda <pgonda@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

---

I am not sure if this is the right path forward maybe just returning
KVM_EXIT_SHUTDOWN is better. But the current behavior is very unhelpful.

---

arch/x86/kvm/svm/svm.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 956726d867aa..547526616d60 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2131,12 +2131,16 @@ static int shutdown_interception(struct kvm_vcpu *vcpu)
* The VM save area has already been encrypted so it
* cannot be reinitialized - just terminate.
*/
- if (sev_es_guest(vcpu->kvm))
- return -EINVAL;
+ if (sev_es_guest(vcpu->kvm)) {
+ vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
+ vcpu->run->system_event.type = KVM_SYSTEM_EVENT_SEV_TERM;
+ kvm_vm_dead(vcpu->kvm);
+ return 0;
+ }

/*
* VMCB is undefined after a SHUTDOWN intercept. INIT the vCPU to put
- * the VMCB in a known good state. Unfortuately, KVM doesn't have
+ * the VMCB in a known good state. Unfortunately, KVM doesn't have
* KVM_MP_STATE_SHUTDOWN and can't add it without potentially breaking
* userspace. At a platform view, INIT is acceptable behavior as
* there exist bare metal platforms that automatically INIT the CPU
--
2.42.0.283.g2d96d420d3-goog