From:   Thomas Gleixner <tglx@linutronix.de>
To:     Krister Johansen <kjlx@templeofstupid.com>,
        xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org
Cc:     Juergen Gross <jgross@suse.com>, Jan Beulich <jbeulich@suse.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Marcelo Tosatti <mtosatti@redhat.com>,
        Anthony Liguori <aliguori@amazon.com>,
        David Reaver <me@davidreaver.com>,
        Brendan Gregg <brendan@intel.com>
Subject: Re: [PATCH linux-next 2/2] x86/xen/time: cleanup
 xen_tsc_safe_clocksource
In-Reply-To: <f6bab47230b00cecb67f2c5d94716c8236609967.1676610413.git.kjlx@templeofstupid.com>
References: <cover.1676610413.git.kjlx@templeofstupid.com>
 <f6bab47230b00cecb67f2c5d94716c8236609967.1676610413.git.kjlx@templeofstupid.com>
Date:   Mon, 20 Feb 2023 23:01:18 +0100
Message-ID: <87h6vgov2p.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Mon, Feb 20 2023 at 09:17, Krister Johansen wrote:
> @@ -495,8 +496,7 @@ static int __init xen_tsc_safe_clocksource(void)
>  	/* Leaf 4, sub-leaf 0 (0x40000x03) */
>  	cpuid_count(xen_cpuid_base() + 3, 0, &eax, &ebx, &ecx, &edx);
>  
> -	/* tsc_mode = no_emulate (2) */
> -	if (ebx != 2)
> +	if (ebx != XEN_CPUID_TSC_MODE_NEVER_EMULATE)
>  		return 0;
>  
>  	return 1;

What about removing more stupidity from that function?

static bool __init xen_tsc_safe_clocksource(void)
{
	u32 eax, ebx. ecx, edx;
 
	/* Leaf 4, sub-leaf 0 (0x40000x03) */
	cpuid_count(xen_cpuid_base() + 3, 0, &eax, &ebx, &ecx, &edx);

	return ebx == XEN_CPUID_TSC_MODE_NEVER_EMULATE;
}

Thanks,

        tglx