On 09/07/2012 03:07 PM, Liu, Jinsong wrote: > Avi Kivity wrote: >>> 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; >> >> I prefer a patch making kvm for x86 depend on hrtimers. kvm already >> provides a high resolution timer to the guest in the local apic, >> backing it with the jiffies event source will likely cause some >> guests to malfunction. > > Yep, I did a draft test for kvm lapic timer, it also worked fail when > CONFIG_HIGH_RES_TIMERS disabled. > > Attached is the udpated patch. > > Thanks, > Jinsong > > ==================== > From 64d0458ec50a7d6917adf1e9735ba6e6ae6024ad Mon Sep 17 00:00:00 2001 > From: Liu, Jinsong <jinsong....@intel.com> > Date: Sat, 8 Sep 2012 03:32:31 +0800 > Subject: [PATCH] KVM: select HIGH_RES_TIMERS when KVM enabled > > This is for 2 reasons: > 1. it's pointless for kvm lapic timer and tsc deadline timer > when kernel hrtimer not configured as high resolution, since > that would be not accurate based on wheel; > 2. kvm lapic timer and 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 then make kvm lapic timer and tsc deadline timer fail. > > Signed-off-by: Liu, Jinsong <jinsong....@intel.com> > --- > arch/x86/kvm/Kconfig | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig > index a28f338..5f861ca 100644 > --- a/arch/x86/kvm/Kconfig > +++ b/arch/x86/kvm/Kconfig > @@ -24,6 +24,8 @@ config KVM > depends on PCI > # for TASKSTATS/TASK_DELAY_ACCT: > depends on NET > + # for HIGH_RES_TIMERS > + depends on !ARCH_USES_GETTIMEOFFSET > select PREEMPT_NOTIFIERS > select MMU_NOTIFIER > select ANON_INODES > @@ -37,6 +39,8 @@ config KVM > select TASK_DELAY_ACCT > select PERF_EVENTS > select HAVE_KVM_MSI > + select GENERIC_CLOCKEVENTS > + select HIGH_RES_TIMERS
hrtimers is an intrusive feature, I don't think we should force-enable it. Please change it to a depends on. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
