linux-kernel - Re: [PATCH v2] KVM: SVM: Fix SNP AP destroy race with VMRUN

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Message-ID: <174562142846.1001255.4839400657801617260.b4-ty@google.com>
Date: Fri, 25 Apr 2025 16:23:22 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	x86@...nel.org, Tom Lendacky <thomas.lendacky@....com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, Ingo Molnar <mingo@...hat.com>, 
	Thomas Gleixner <tglx@...utronix.de>, Michael Roth <michael.roth@....com>
Subject: Re: [PATCH v2] KVM: SVM: Fix SNP AP destroy race with VMRUN

On Thu, 27 Mar 2025 12:39:56 -0500, Tom Lendacky wrote:
> An AP destroy request for a target vCPU is typically followed by an
> RMPADJUST to remove the VMSA attribute from the page currently being
> used as the VMSA for the target vCPU. This can result in a vCPU that
> is about to VMRUN to exit with #VMEXIT_INVALID.
> 
> This usually does not happen as APs are typically sitting in HLT when
> being destroyed and therefore the vCPU thread is not running at the time.
> However, if HLT is allowed inside the VM, then the vCPU could be about to
> VMRUN when the VMSA attribute is removed from the VMSA page, resulting in
> a #VMEXIT_INVALID when the vCPU actually issues the VMRUN and causing the
> guest to crash. An RMPADJUST against an in-use (already running) VMSA
> results in a #NPF for the vCPU issuing the RMPADJUST, so the VMSA
> attribute cannot be changed until the VMRUN for target vCPU exits. The
> Qemu command line option '-overcommit cpu-pm=on' is an example of allowing
> HLT inside the guest.
> 
> [...]

Applied to kvm-x86 svm, thanks!

[1/1] KVM: SVM: Fix SNP AP destroy race with VMRUN
      https://github/kvm-x86/linux/commit/309d28576f0a

--
https://github.com/kvm-x86/linux/tree/next