linux-kernel - Re: [PATCH 0/9] KVM: SVM: Fix (hilarious) exit

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Message-ID: <176494714145.295908.1538917525859193574.b4-ty@google.com>
Date: Fri,  5 Dec 2025 08:59:31 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Vitaly Kuznetsov <vkuznets@...hat.com>, "K. Y. Srinivasan" <kys@...rosoft.com>, 
	Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>, 
	Dexuan Cui <decui@...rosoft.com>
Cc: kvm@...r.kernel.org, linux-hyperv@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Jim Mattson <jmattson@...gle.com>, 
	Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: Re: [PATCH 0/9] KVM: SVM: Fix (hilarious) exit_code bugs

On Thu, 13 Nov 2025 14:56:12 -0800, Sean Christopherson wrote:
> Hyper-V folks, y'all are getting Cc'd because of a change in
> include/hyperv/hvgdk.h to ensure HV_SVM_EXITCODE_ENL is an unsigned value.
> AFAICT, only KVM consumes that macro.  That said, any insight you can provide
> on relevant Hyper-V behavior would be appreciated :-)
> 
> 
> Fix bugs in SVM that mostly impact nested SVM where KVM treats exit codes
> as 32-bit values instead of 64-bit values.  I have no idea how KVM ended up
> with such an egregious flaw, as the blame trail goes all the way back to
> commit 6aa8b732ca01 ("[PATCH] kvm: userspace interface").  Maybe there was
> pre-production hardware or something?
> 
> [...]

Applied 1 and 2 to kvm-x86 fixes.  I'll send v2 for the rest soon-ish.

[1/9] KVM: nSVM: Clear exit_code_hi in VMCB when synthesizing nested VM-Exits
      https://github.com/kvm-x86/linux/commit/da01f64e7470
[2/9] KVM: nSVM: Set exit_code_hi to -1 when synthesizing SVM_EXIT_ERR (failed VMRUN)
      https://github.com/kvm-x86/linux/commit/f402ecd7a8b6

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