linux-kernel - Re: [PATCH v15 14/41] KVM: VMX: Emulate read and write to CET MSRs

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

Message-ID: <6a638dc4-bd99-4a93-8498-2ba1c0c61b30@intel.com>
Date: Tue, 16 Sep 2025 16:10:21 +0800
From: Xiaoyao Li <xiaoyao.li@...el.com>
To: Chao Gao <chao.gao@...el.com>
Cc: Sean Christopherson <seanjc@...gle.com>,
 Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, Tom Lendacky <thomas.lendacky@....com>,
 Mathias Krause <minipli@...ecurity.net>, John Allen <john.allen@....com>,
 Rick Edgecombe <rick.p.edgecombe@...el.com>,
 Maxim Levitsky <mlevitsk@...hat.com>, Zhang Yi Z <yi.z.zhang@...ux.intel.com>
Subject: Re: [PATCH v15 14/41] KVM: VMX: Emulate read and write to CET MSRs

On 9/16/2025 3:48 PM, Chao Gao wrote:
> On Tue, Sep 16, 2025 at 03:07:06PM +0800, Xiaoyao Li wrote:
>> On 9/13/2025 7:22 AM, Sean Christopherson wrote:
>>> From: Yang Weijiang <weijiang.yang@...el.com>
>>>
>>> Add emulation interface for CET MSR access. The emulation code is split
>>> into common part and vendor specific part. The former does common checks
>>> for MSRs, e.g., accessibility, data validity etc., then passes operation
>>> to either XSAVE-managed MSRs via the helpers or CET VMCS fields.
>>>
>>> SSP can only be read via RDSSP. Writing even requires destructive and
>>> potentially faulting operations such as SAVEPREVSSP/RSTORSSP or
>>> SETSSBSY/CLRSSBSY. Let the host use a pseudo-MSR that is just a wrapper
>>> for the GUEST_SSP field of the VMCS.
>>>
>>> Suggested-by: Sean Christopherson <seanjc@...gle.com>
>>> Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
>>> Tested-by: Mathias Krause <minipli@...ecurity.net>
>>> Tested-by: John Allen <john.allen@....com>
>>> Tested-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
>>> Signed-off-by: Chao Gao <chao.gao@...el.com>
>>> [sean: drop call to kvm_set_xstate_msr() for S_CET, consolidate code]
>>
>> Is the change/update of "drop call to kvm_set_xstate_msr() for S_CET" true
>> for this patch?
> 
> v14 has that call, but it is incorrect. So Sean dropped it. See v14:
> 
> https://lore.kernel.org/kvm/20250909093953.202028-12-chao.gao@intel.com/

Sorry, my fault. I missed it somehow, when bouncing between the 3 MSR 
handlers.

>>
>>> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
>>
>> Reviewed-by: Xiaoyao Li <xiaoyao.li@...el.com>