linux-kernel - Re: [PATCH v4 1/8] x86/bugs: Use VM_CLEAR_CPU

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: <20251112102336.GAaRRgKJ6lHCKQgxdd@fat_crate.local>
Date: Wed, 12 Nov 2025 11:23:36 +0100
From: Borislav Petkov <bp@...en8.de>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Brendan Jackman <jackmanb@...gle.com>
Subject: Re: [PATCH v4 1/8] x86/bugs: Use VM_CLEAR_CPU_BUFFERS in VMX as well

On Tue, Nov 11, 2025 at 02:03:40PM -0800, Sean Christopherson wrote:
> How about:
> 
> /* If necessary, emit VERW on exit-to-userspace to clear CPU buffers. */
> #define CLEAR_CPU_BUFFERS \
> 	ALTERNATIVE "", __CLEAR_CPU_BUFFERS, X86_FEATURE_CLEAR_CPU_BUF

By the "If necessary" you mean whether X86_FEATURE_CLEAR_CPU_BUF is set or
not, I presume...

I was just wondering whether this macro is going to be used somewhere else
*except* on the kernel->user vector.

> Ya, and this goes away (moved into SVM) by the end of the series.

Aha, lemme look at the rest too then.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette