linux-kernel - Re: [PATCH v5 1/9] KVM: VMX: Use on-stack copy of @flags in __vmx_vcpu

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: <20251114164038.GDaRdbhpoLbiq02vDu@fat_crate.local>
Date: Fri, 14 Nov 2025 17:40:38 +0100
From: Borislav Petkov <bp@...en8.de>
To: Sean Christopherson <seanjc@...gle.com>
Cc: 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,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
	Brendan Jackman <jackmanb@...gle.com>
Subject: Re: [PATCH v5 1/9] KVM: VMX: Use on-stack copy of @flags in
 __vmx_vcpu_run()

On Thu, Nov 13, 2025 at 03:37:38PM -0800, Sean Christopherson wrote:
> Suggested-by: Borislav Petkov <bp@...en8.de>

Bah, I didn't suggest that - that's all your effort :)

> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kvm/vmx/run_flags.h | 10 +++-------
>  arch/x86/kvm/vmx/vmenter.S   | 13 ++++---------
>  2 files changed, 7 insertions(+), 16 deletions(-)

...

> @@ -173,8 +167,9 @@ SYM_FUNC_START(__vmx_vcpu_run)
>  	/* Clobbers EFLAGS.ZF */
>  	CLEAR_CPU_BUFFERS
>  
> -	/* Check EFLAGS.CF from the VMX_RUN_VMRESUME bit test above. */
> -	jnc .Lvmlaunch
> +	/* Check @flags to see if vmlaunch or vmresume is needed. */

VMRESUME/VMLAUNCH in caps, like the rest of the file. We like our x86 insns in
all caps. :)

> +	testl $VMX_RUN_VMRESUME, WORD_SIZE(%_ASM_SP)
> +	jz .Lvmlaunch
>  
>  	/*
>  	 * After a successful VMRESUME/VMLAUNCH, control flow "magically"
> -- 

But yeah, AFAIU this code, that's a nice cleanup.

Acked-by: Borislav Petkov (AMD) <bp@...en8.de>

-- 
Regards/Gruss,
    Boris.

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