>From 728a17e2de591b557c3c8ba31076b4bf2ca5ab42 Mon Sep 17 00:00:00 2001 From: Liu, Jinsong <jinsong.liu@xxxxxxxxx> Date: Wed, 5 Sep 2012 03:18:15 +0800 Subject: [PATCH] KVM: tsc deadline timer works only when hrtimer high resolution configured This is for 2 reasons: 1. it's pointless to enable tsc deadline timer to guest when kernel hrtimer not configured as high resolution, since that would be un-precise based on wheel; 2. tsc deadline timer based on hrtimer, setting a leftmost node to rb tree and then do hrtimer reprogram. If hrtimer not configured as high resolution, hrtimer_enqueue_reprogram do nothing and would make tsc deadline timer fail. Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx> --- arch/x86/kvm/x86.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 148ed66..0e64997 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2210,7 +2210,11 @@ int kvm_dev_ioctl_check_extension(long ext) r = kvm_has_tsc_control; break; case KVM_CAP_TSC_DEADLINE_TIMER: +#ifdef CONFIG_HIGH_RES_TIMERS r = boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER); +#else + r = 0; +#endif break; default: r = 0; -- 1.7.1
Attachment:
0001-KVM-tsc-deadline-timer-works-only-when-hrtimer-high-.patch
Description: 0001-KVM-tsc-deadline-timer-works-only-when-hrtimer-high-.patch
