From: Sean Christopherson <seanjc@google.com>
To: Kevin Cheng <chengkev@google.com>
Cc: pbonzini@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, yosry.ahmed@linux.dev
Subject: Re: [PATCH V3 2/5] KVM: SVM: Inject #UD for STGI if EFER.SVME=0 and SVM Lock and DEV are not available
Date: Thu, 12 Feb 2026 13:18:24 -0800 [thread overview]
Message-ID: <aY5DoEINs4PhXv7_@google.com> (raw)
In-Reply-To: <aY5DHUQl3jWnk3TN@google.com>
On Thu, Feb 12, 2026, Sean Christopherson wrote:
> On Thu, Jan 22, 2026, Kevin Cheng wrote:
> > The AMD APM states that STGI causes a #UD if SVM is not enabled and
> > neither SVM Lock nor the device exclusion vector (DEV) are supported.
> > Support for DEV is part of the SKINIT architecture. Fix the STGI exit
> > handler by injecting #UD when these conditions are met.
>
> This is entirely pointless. SVML and SKINIT can never bet set in guest caps.
> There are many things that are documented in the SDM/APM that don't have "correct"
> handling in KVM, because they're completely unsupported.
>
> _If_ this is causing someone enough heartburn to want to "fix", just add a comment
> in nested_svm_check_permissions() stating that KVM doesn't support SVML or SKINIT.
Case in point, patch 4 is flawed because it forces interception of STGI if
EFER.SVME=0. I.e. by trying to handle the impossible, you're introducing new
and novel ways for KVM to do things "wrong".
next prev parent reply other threads:[~2026-02-12 21:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-22 4:57 [PATCH V3 0/5] Align SVM with APM defined behaviors Kevin Cheng
2026-01-22 4:57 ` [PATCH V3 1/5] KVM: SVM: Move STGI and CLGI intercept handling Kevin Cheng
2026-01-22 4:57 ` [PATCH V3 2/5] KVM: SVM: Inject #UD for STGI if EFER.SVME=0 and SVM Lock and DEV are not available Kevin Cheng
2026-02-12 21:16 ` Sean Christopherson
2026-02-12 21:18 ` Sean Christopherson [this message]
2026-02-12 21:57 ` Kevin Cheng
2026-02-13 15:06 ` Sean Christopherson
2026-01-22 4:57 ` [PATCH V3 3/5] KVM: SVM: Inject #UD for INVLPGA if EFER.SVME=0 Kevin Cheng
2026-01-22 4:57 ` [PATCH V3 4/5] KVM: SVM: Recalc instructions intercepts when EFER.SVME is toggled Kevin Cheng
2026-01-22 4:57 ` [PATCH V3 5/5] KVM: SVM: Raise #UD if VMMCALL instruction is not intercepted Kevin Cheng
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