linux-kernel - Re: [PATCH v15 29/41] KVM: SEV: Synchronize MSR_IA32

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: <nvd4fg4mfd6cdcnqqaqyaqthn5ljuzswplvnslpv2pkuano4mf@yn45t5solwzp>
Date: Mon, 22 Sep 2025 10:54:23 +0100
From: Kiryl Shutsemau <kas@...nel.org>
To: "Upadhyay, Neeraj" <neeraj.upadhyay@....com>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>, 
	"thomas.lendacky@....com" <thomas.lendacky@....com>, "john.allen@....com" <john.allen@....com>, 
	"Gao, Chao" <chao.gao@...el.com>, "seanjc@...gle.com" <seanjc@...gle.com>, 
	"Li, Xiaoyao" <xiaoyao.li@...el.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"minipli@...ecurity.net" <minipli@...ecurity.net>, "mlevitsk@...hat.com" <mlevitsk@...hat.com>, 
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>, "pbonzini@...hat.com" <pbonzini@...hat.com>, naveen.rao@....com
Subject: Re: [PATCH v15 29/41] KVM: SEV: Synchronize MSR_IA32_XSS from the
 GHCB when it's valid

On Mon, Sep 22, 2025 at 03:03:59PM +0530, Upadhyay, Neeraj wrote:
> 
> > 
> > In TDX case, VAPIC state is protected VMM. It covers ISR, so guest can
> > safely check ISR to detect if the exception is external or internal.
> > 
> > IIUC, VAPIC state is controlled by VMM in SEV case and ISR is not
> > reliable.
> > 
> > I am not sure if Secure AVIC[1] changes the situation for AMD.
> > 
> > Neeraj?
> > 
> 
> For Secure AVIC enabled guests, guest's vAPIC ISR state is not visible to
> (and not controlled by) host or VMM.

In this case, I think you should make ia32_disable() in sme_early_init()
conditional on !Secure AVIC.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov