linux-kernel - Re: [PATCH 2/3] KVM: nSVM: Propagate SVM_EXIT_CR0_SEL

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 for Android: free password hash cracker in your pocket

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

Message-ID: <42uppdj3ehrnihk7xnejblgla6enenqgredjpe4vknur7iof6r@4d2yi6zataqp>
Date: Wed, 5 Nov 2025 19:59:17 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jim Mattson <jmattson@...gle.com>, 
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org, stable@...r.kernel, 
	Matteo Rizzo <matteorizzo@...gle.com>
Subject: Re: [PATCH 2/3] KVM: nSVM: Propagate SVM_EXIT_CR0_SEL_WRITE
 correctly for LMSW emulation

On Wed, Nov 05, 2025 at 11:44:27AM -0800, Sean Christopherson wrote:
> On Fri, Oct 24, 2025, Yosry Ahmed wrote:
> > When emulating L2 instructions, svm_check_intercept() checks whether a
> > write to CR0 should trigger a synthesized #VMEXIT with
> > SVM_EXIT_CR0_SEL_WRITE. For MOV-to-CR0, SVM_EXIT_CR0_SEL_WRITE is only
> > triggered if any bit other than CR0.MP and CR0.TS is updated. However,
> > according to the APM (24593—Rev.  3.42—March 2024, Table 15-7):
> > 
> >   The LMSW instruction treats the selective CR0-write
> >   intercept as a non-selective intercept (i.e., it intercepts
> >   regardless of the value being written).
> > 
> > Skip checking the changed bits for x86_intercept_lmsw and always inject
> > SVM_EXIT_CR0_SEL_WRITE.
> > 
> > Fixes: cfec82cb7d31 ("KVM: SVM: Add intercept check for emulated cr accesses")
> > Cc: stable@...r.kernel
> 
> Bad email (mostly in case you're using a macro for this; the next patch has the
> same typo).

Yeah I realized after sending it. Will fixup if there's a new version.