From: Sean Christopherson <seanjc@google.com>
To: Kim Phillips <kim.phillips@amd.com>
Cc: kvm@vger.kernel.org, linux-coco@lists.linux.dev,
linux-kernel@vger.kernel.org, x86@kernel.org,
Tom Lendacky <thomas.lendacky@amd.com>,
Michael Roth <michael.roth@amd.com>,
Ashish Kalra <ashish.kalra@amd.com>,
"Nikunj A . Dadhania" <nikunj@amd.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2 2/2] KVM: SEV: Configure "ALLOWED_SEV_FEATURES" VMCB Field
Date: Thu, 22 Aug 2024 16:31:44 -0700 [thread overview]
Message-ID: <ZsfKYHFkWA-Rh23C@google.com> (raw)
In-Reply-To: <20240822221938.2192109-3-kim.phillips@amd.com>
On Thu, Aug 22, 2024, Kim Phillips wrote:
> AMD EPYC 5th generation processors have introduced a feature that allows
> the hypervisor to control the SEV_FEATURES that are set for, or by, a
> guest [1]. ALLOWED_SEV_FEATURES can be used by the hypervisor to enforce
> that SEV-ES and SEV-SNP guests cannot enable features that the
> hypervisor does not want to be enabled.
>
> When ALLOWED_SEV_FEATURES is enabled, a VMRUN will fail if any
> non-reserved bits are 1 in SEV_FEATURES but are 0 in
> ALLOWED_SEV_FEATURES.
This may need additional uAPI so that userspace can opt-in. Dunno. I hope guests
aren't abusing features, but IIUC, flipping this on has the potential to break
existing VMs, correct?
prev parent reply other threads:[~2024-08-22 23:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-22 22:19 [PATCH v2 0/2] KVM: SEV: Add support for the ALLOWED_SEV_FEATURES feature Kim Phillips
2024-08-22 22:19 ` [PATCH v2 1/2] x86/cpufeatures: Add "Allowed SEV Features" Feature Kim Phillips
2024-08-25 12:35 ` Thomas Gleixner
2024-08-22 22:19 ` [PATCH v2 2/2] KVM: SEV: Configure "ALLOWED_SEV_FEATURES" VMCB Field Kim Phillips
2024-08-22 23:31 ` Sean Christopherson [this message]
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