linux-kernel - Re: [PATCH v3 05/10] KVM: TDX: restore host xsave state when exit from the guest TD

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: <CABgObfZOhNtk0DKq+nB2UC+FFhsEkyiysngZoovoJP-vF43bYA@mail.gmail.com>
Date: Wed, 12 Mar 2025 12:36:58 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: Xiaoyao Li <xiaoyao.li@...el.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org, adrian.hunter@...el.com, 
	seanjc@...gle.com, rick.p.edgecombe@...el.com, 
	Isaku Yamahata <isaku.yamahata@...el.com>
Subject: Re: [PATCH v3 05/10] KVM: TDX: restore host xsave state when exit
 from the guest TD

On Mon, Mar 10, 2025 at 8:24 AM Xiaoyao Li <xiaoyao.li@...el.com> wrote:
>
> On 3/8/2025 5:20 AM, Paolo Bonzini wrote:
> > From: Isaku Yamahata <isaku.yamahata@...el.com>
> >
> > On exiting from the guest TD, xsave state is clobbered; restore it.
>
> I prefer the implementation as this patch, which is straightforward.
> (I would be much better if the changelog can describe more)

Ok:

Do not use kvm_load_host_xsave_state(), as it relies on vcpu->arch
to find out whether other KVM_RUN code has loaded guest state into
XCR0/PKRU/XSS or not.  In the case of TDX, the exit values are known
independent of the guest CR0 and CR4, and in fact the latter are not
available.

Thanks!

Paolo