On Wed, Sep 06, 2023, Tom Lendacky wrote:
> On 9/6/23 10:14, Peter Gonda wrote:
> > Currently if an SEV-ES VM shuts down userspace sees KVM_RUN struct with
>
> s/down userspace/down, userspace/
Heh, yeah, I read that the same way you did.
> > only the INVALID_ARGUMENT. This is a very limited amount of information
> > to debug the situation. Instead KVM can return a
> > KVM_EXIT_SHUTDOWN to alert userspace the VM is shutting down and
> > is not usable any further.
> >
> > Signed-off-by: Peter Gonda <pgonda@xxxxxxxxxx>
> > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
> > Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
> > Cc: Joerg Roedel <joro@xxxxxxxxxx>
> > Cc: Borislav Petkov <bp@xxxxxxxxx>
> > Cc: x86@xxxxxxxxxx
> > Cc: kvm@xxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> >
> > ---
> > arch/x86/kvm/svm/svm.c | 8 +++++---
> > 1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > index 956726d867aa..cecf6a528c9b 100644
> > --- a/arch/x86/kvm/svm/svm.c
> > +++ b/arch/x86/kvm/svm/svm.c
> > @@ -2131,12 +2131,14 @@ 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)) {
> > + kvm_run->exit_reason = KVM_EXIT_SHUTDOWN;
> > + return 0;
> > + }
>
> Just a nit... feel free to ignore, but, since KVM_EXIT_SHUTDOWN is also set
> at the end of the function and I don't think kvm_vcpu_reset() clears the
> value from kvm_run, you could just set kvm_run->exit_reason on entry and
> just return 0 early for an SEV-ES guest.
kvm_run is writable by userspace though, so KVM can't rely on kvm_run->exit_reason
for correctness.
And IIUC, the VMSA is also toast, i.e. doing anything other than marking the VM
dead is futile, no?
