[PATCH] KVM: tsc deadline timer works only when hrtimer high resol=

[Liu , Jinsong]

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 =3D kvm_has_tsc_control;
 		break;
 	case KVM_CAP_TSC_DEADLINE_TIMER:
+#ifdef CONFIG_HIGH_RES_TIMERS
 		r =3D boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER);
+#else
+		r =3D 0;
+#endif
 		break;
 	default:
 		r =3D 0;
--=20
1.7.1

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	size=1218; creation-date="Tue, 04 Sep 2012 11:48:55 GMT";
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