linux-kernel - Re: [PATCH RESEND v2 2/3] x86/cpu: Add setcpuid cmdline param

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Message-ID: <20250217110334.GHZ7MXhq4xNWSkKHCH@fat_crate.local>
Date: Mon, 17 Feb 2025 12:03:34 +0100
From: Borislav Petkov <bp@...en8.de>
To: Brendan Jackman <jackmanb@...gle.com>
Cc: Jonathan Corbet <corbet@....net>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v2 2/3] x86/cpu: Add setcpuid cmdline param

On Wed, Jan 29, 2025 at 03:35:40PM +0000, Brendan Jackman wrote:
> In preparation for adding support to fake out CPU bugs, add a general
> facility to force enablement of CPU flags.

"... to force-enable ..."

> 
> The flag taints the kernel and the documentation attempts to be clear
> that this is highly unsuitable for uses outside of kernel development
> and platform experimentation.
> 
> The new arg is parsed just like clearcpuid, but instead of leading to
> setup_clear_cpu_cap() it leads to setup_force_cpu_cap().
> 
> I've tested this by booting a nested QEMU guest on an Intel host, which
> with setcpuid=svm will claim that it supports AMD virtualization.

Move this sentence...

> Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
> ---

... here as it doesn't belong in a commit message.

-- 
Regards/Gruss,
    Boris.

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