2024-02-23 10:42:37

by Paolo Bonzini

Subject: [PATCH v2 06/11] KVM: SEV: disable DEBUG_SWAP by default

Disable all VMSA features in KVM_SEV_INIT and KVM_SEV_ES_INIT. They are
not actually supported by SEV (a SEV guest does not have a VMSA to which
you can apply features) and they cause unexpected changes in measurement
for SEV-ES.

Going on, the way to enable them will be to use a new initialization ioctl
that takes the VMSA features as a parameter.

Signed-off-by: Paolo Bonzini <[email protected]>
---
arch/x86/kvm/svm/sev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index b0e97f9617e3..06e03a6fe7e4 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -267,7 +267,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)

sev->active = true;
sev->es_active = argp->id == KVM_SEV_ES_INIT;
- sev->vmsa_features = sev_supported_vmsa_features;
+ sev->vmsa_features = 0;

asid = sev_asid_new(sev);
if (asid < 0)
--
2.39.1

2024-02-23 16:17:08

by Sean Christopherson

Subject: Re: [PATCH v2 06/11] KVM: SEV: disable DEBUG_SWAP by default

On Fri, Feb 23, 2024, Paolo Bonzini wrote:
> Disable all VMSA features in KVM_SEV_INIT and KVM_SEV_ES_INIT. They are
> not actually supported by SEV (a SEV guest does not have a VMSA to which
> you can apply features) and they cause unexpected changes in measurement
> for SEV-ES.

Sorry :-(

I've done my best to avoid having to deal with attestation, so it's a bit of a
blind spot for me.