lkml.org 
[lkml]   [2020]   [Jul]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip: x86/timers] x86/xen/time: Set the X86_FEATURE_TSC_KNOWN_FREQ flag in xen_tsc_khz()
The following commit has been merged into the x86/timers branch of tip:

Commit-ID: 898ec52d2ba05915aaedcdb21bff2e944c883cb8
Gitweb: https://git.kernel.org/tip/898ec52d2ba05915aaedcdb21bff2e944c883cb8
Author: Hayato Ohhashi <o8@vmm.dev>
AuthorDate: Tue, 21 Jul 2020 16:12:31
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 25 Jul 2020 15:49:41 +02:00

x86/xen/time: Set the X86_FEATURE_TSC_KNOWN_FREQ flag in xen_tsc_khz()

If the TSC frequency is known from the pvclock page,
the TSC frequency does not need to be recalibrated.

We can avoid recalibration by setting X86_FEATURE_TSC_KNOWN_FREQ.

Signed-off-by: Hayato Ohhashi <o8@vmm.dev>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20200721161231.6019-1-o8@vmm.dev
---
arch/x86/xen/time.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index c8897aa..91f5b33 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -39,6 +39,7 @@ static unsigned long xen_tsc_khz(void)
struct pvclock_vcpu_time_info *info =
&HYPERVISOR_shared_info->vcpu_info[0].time;

+ setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
return pvclock_tsc_khz(info);
}

\
 
 \ /
  Last update: 2020-07-25 15:54    [W:1.467 / U:0.716 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site