linux-kernel - [PATCH linux-next v2 2/2] x86/xen/time: cleanup xen_tsc_safe

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Date:   Wed, 22 Feb 2023 09:54:56 -0800
From:   Krister Johansen <kjlx@...pleofstupid.com>
To:     xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>, Jan Beulich <jbeulich@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Anthony Liguori <aliguori@...zon.com>,
        David Reaver <me@...idreaver.com>,
        Brendan Gregg <brendan@...el.com>
Subject: [PATCH linux-next v2 2/2] x86/xen/time: cleanup
 xen_tsc_safe_clocksource

Modifies xen_tsc_safe_clocksource() to use newly defined constants from
arch/x86/include/asm/xen/cpuid.h.  This replaces a numeric value with
XEN_CPUID_TSC_MODE_NEVER_EMULATE, and deletes a comment that is now self
explanatory.

There should be no change in the function's behavior.

Signed-off-by: Krister Johansen <kjlx@...pleofstupid.com>
---
 arch/x86/xen/time.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 95140609c8a8..94056013a2a4 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -20,6 +20,7 @@
 #include <asm/pvclock.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
+#include <asm/xen/cpuid.h>
 
 #include <xen/events.h>
 #include <xen/features.h>
@@ -495,11 +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)
-		return 0;
-
-	return 1;
+	return ebx == XEN_CPUID_TSC_MODE_NEVER_EMULATE;
 }
 
 static void __init xen_time_init(void)
-- 
2.25.1