Avi Kivity wrote: > 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.liu@xxxxxxxxx> >> 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.liu@xxxxxxxxx> --- >> 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. Hmm, if it changed as config KVM depends on HIGH_RES_TIMERS The item 'Kernel-based Virtual Machine (KVM) support (NEW)' even didn't appear to user when make menuconfig (when HIGH_RES_TIMERS disable) Is it good? I just have a little concern here:) Thanks, Jinsong-- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
