Re: [PATCH] x86/msr: Remove misleading "unrecognized" wording in write warning

[Borislav Petkov]

On Wed, Mar 25, 2026 at 06:48:52PM +0100, Roman Storozhenko wrote:
> The term "unrecognized" in the warning message
> 
>   "Write to unrecognized MSR..."
> 
>   creates the impression that the MSR access is invalid or
>   prohibited, which is not necessarily the case.
> 
>   Remove this wording to avoid misleading users about the nature
>   of the access.
> 
> Signed-off-by: Roman Storozhenko <romeusmeister@xxxxxxxxx>
> ---
> Additional context:
> 
> A utility that uses direct MSR writes triggered this warning during
> post-silicon validation. The message was interpreted as evidence of
> incorrect or prohibited MSR access due to the use of the term
> "unrecognized".
> 
> This led to confusion among validation teams, although the MSR accesses
> were intentional and valid.
> 
> Clarify the message to avoid misleading users in similar scenarios.
> ---
>  arch/x86/kernel/msr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
> index 4469c784eaa0..16f6cde7d471 100644
> --- a/arch/x86/kernel/msr.c
> +++ b/arch/x86/kernel/msr.c
> @@ -98,7 +98,7 @@ static int filter_write(u32 reg)
>  	if (!__ratelimit(&fw_rs))
>  		return 0;
>  
> -	pr_warn("Write to unrecognized MSR 0x%x by %s (pid: %d), tainting CPU_OUT_OF_SPEC.\n",
> +	pr_warn("Write to MSR 0x%x by %s (pid: %d), tainting CPU_OUT_OF_SPEC.\n",
>  	        reg, current->comm, current->pid);
>  	pr_warn("See https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/about for details.\n");
>  
> 
> ---

# modprobe msr allow_writes=on
# grep -r . /sys/module/msr/parameters/allow_writes 
on

-- 
Regards/Gruss,
    Boris.

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