linux-kernel - Re: [PATCH] KVM: x86: Call out MSR_IA32_S

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <176227794159.3934184.6943075964127868106.b4-ty@google.com>
Date: Tue,  4 Nov 2025 09:44:56 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Chao Gao <chao.gao@...el.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Binbin Wu <binbin.wu@...ux.intel.com>, 
	Xiaoyao Li <xiaoyao.li@...el.com>
Subject: Re: [PATCH] KVM: x86: Call out MSR_IA32_S_CET is not handled by XSAVES

On Mon, 27 Oct 2025 23:01:41 -0700, Chao Gao wrote:
> Update the comment above is_xstate_managed_msr() to note that
> MSR_IA32_S_CET isn't saved/restored by XSAVES/XRSTORS.
> 
> MSR_IA32_S_CET isn't part of CET_U/S state as the SDM states:
>   The register state used by Control-Flow Enforcement Technology (CET)
>   comprises the two 64-bit MSRs (IA32_U_CET and IA32_PL3_SSP) that manage
>   CET when CPL = 3 (CET_U state); and the three 64-bit MSRs
>   (IA32_PL0_SSP–IA32_PL2_SSP) that manage CET when CPL < 3 (CET_S state).
> 
> [...]

Applied to kvm-x86 fixes, with an opportunistic tweak of the comment (the whole
spiel about the safety was attached to the wrong function).  Thanks!

[1/1] KVM: x86: Call out MSR_IA32_S_CET is not handled by XSAVES
      https://github.com/kvm-x86/linux/commit/cab4098be418

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