From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Lieven Subject: Re: [RFC PATCH v3 1/2] add support for Hyper-V reference time counter Date: Wed, 08 Jan 2014 12:48:02 +0100 Message-ID: <52CD3AF2.3040108@dlhnet.de> References: <1386502419-26614-1-git-send-email-vrozenfe@redhat.com> <1386502419-26614-2-git-send-email-vrozenfe@redhat.com> <20131211185305.GA28207@amt.cnet> <20131211185904.GB28207@amt.cnet> <52C59941.4090200@dlhnet.de> <1389087361.10148.55.camel@localhost> <52CC3ED3.5070804@dlhnet.de> <1389174021.9714.7.camel@localhost> <52CD2553.60903@dlhnet.de> <1389177885.9714.21.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org, pbonzini@redhat.com To: Vadim Rozenfeld Return-path: Received: from ssl.dlhnet.de ([82.141.21.42]:48078 "EHLO ssl.dlhnet.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755160AbaAHLqX (ORCPT ); Wed, 8 Jan 2014 06:46:23 -0500 In-Reply-To: <1389177885.9714.21.camel@localhost> Sender: kvm-owner@vger.kernel.org List-ID: On 08.01.2014 11:44, Vadim Rozenfeld wrote: > On Wed, 2014-01-08 at 11:15 +0100, Peter Lieven wrote: >> On 08.01.2014 10:40, Vadim Rozenfeld wrote: >>> On Tue, 2014-01-07 at 18:52 +0100, Peter Lieven wrote: >>>> Am 07.01.2014 10:36, schrieb Vadim Rozenfeld: >>>>> On Thu, 2014-01-02 at 17:52 +0100, Peter Lieven wrote: >>>>>> Am 11.12.2013 19:59, schrieb Marcelo Tosatti: >>>>>>> On Wed, Dec 11, 2013 at 04:53:05PM -0200, Marcelo Tosatti wrote: >>>>>>>> On Sun, Dec 08, 2013 at 10:33:38PM +1100, Vadim Rozenfeld wrote: >>>>>>>>> Signed-off: Peter Lieven >>>>>>>>> Signed-off: Gleb Natapov >>>>>>>>> Signed-off: Vadim Rozenfeld >>>>>>>>> >>>>>>>>> v1 -> v2 >>>>>>>>> 1. mark TSC page dirty as suggested by >>>>>>>>> Eric Northup and Gleb >>>>>>>>> 2. disable local irq when calling get_kernel_ns, >>>>>>>>> as it was done by Peter Lieven >>>>>>>>> 3. move check for TSC page enable from second patch >>>>>>>>> to this one. >>>>>>>>> >>>>>>>>> --- >>>>>>>>> arch/x86/include/asm/kvm_host.h | 2 ++ >>>>>>>>> arch/x86/include/uapi/asm/hyperv.h | 13 +++++++++++++ >>>>>>>>> arch/x86/kvm/x86.c | 39 +++++++++++++++++++++++++++++++++++++- >>>>>>>>> include/uapi/linux/kvm.h | 1 + >>>>>>>>> 4 files changed, 54 insertions(+), 1 deletion(-) >>>>>>>>> >>>>>>>>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >>>>>>>>> index ae5d783..2fd0753 100644 >>>>>>>>> --- a/arch/x86/include/asm/kvm_host.h >>>>>>>>> +++ b/arch/x86/include/asm/kvm_host.h >>>>>>>>> @@ -605,6 +605,8 @@ struct kvm_arch { >>>>>>>>> /* fields used by HYPER-V emulation */ >>>>>>>>> u64 hv_guest_os_id; >>>>>>>>> u64 hv_hypercall; >>>>>>>>> + u64 hv_ref_count; >>>>>>>>> + u64 hv_tsc_page; >>>>>>>>> >>>>>>>>> #ifdef CONFIG_KVM_MMU_AUDIT >>>>>>>>> int audit_point; >>>>>>>>> diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h >>>>>>>>> index b8f1c01..462efe7 100644 >>>>>>>>> --- a/arch/x86/include/uapi/asm/hyperv.h >>>>>>>>> +++ b/arch/x86/include/uapi/asm/hyperv.h >>>>>>>>> @@ -28,6 +28,9 @@ >>>>>>>>> /* Partition Reference Counter (HV_X64_MSR_TIME_REF_COUNT) available*/ >>>>>>>>> #define HV_X64_MSR_TIME_REF_COUNT_AVAILABLE (1 << 1) >>>>>>>>> >>>>>>>>> +/* A partition's reference time stamp counter (TSC) page */ >>>>>>>>> +#define HV_X64_MSR_REFERENCE_TSC 0x40000021 >>>>>>>>> + >>>>>>>>> /* >>>>>>>>> * There is a single feature flag that signifies the presence of the MSR >>>>>>>>> * that can be used to retrieve both the local APIC Timer frequency as >>>>>>>>> @@ -198,6 +201,9 @@ >>>>>>>>> #define HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_MASK \ >>>>>>>>> (~((1ull << HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_SHIFT) - 1)) >>>>>>>>> >>>>>>>>> +#define HV_X64_MSR_TSC_REFERENCE_ENABLE 0x00000001 >>>>>>>>> +#define HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT 12 >>>>>>>>> + >>>>>>>>> #define HV_PROCESSOR_POWER_STATE_C0 0 >>>>>>>>> #define HV_PROCESSOR_POWER_STATE_C1 1 >>>>>>>>> #define HV_PROCESSOR_POWER_STATE_C2 2 >>>>>>>>> @@ -210,4 +216,11 @@ >>>>>>>>> #define HV_STATUS_INVALID_ALIGNMENT 4 >>>>>>>>> #define HV_STATUS_INSUFFICIENT_BUFFERS 19 >>>>>>>>> >>>>>>>>> +typedef struct _HV_REFERENCE_TSC_PAGE { >>>>>>>>> + __u32 tsc_sequence; >>>>>>>>> + __u32 res1; >>>>>>>>> + __u64 tsc_scale; >>>>>>>>> + __s64 tsc_offset; >>>>>>>>> +} HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE; >>>>>>>>> + >>>>>>>>> #endif >>>>>>>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >>>>>>>>> index 21ef1ba..5e4e495a 100644 >>>>>>>>> --- a/arch/x86/kvm/x86.c >>>>>>>>> +++ b/arch/x86/kvm/x86.c >>>>>>>>> @@ -840,7 +840,7 @@ EXPORT_SYMBOL_GPL(kvm_rdpmc); >>>>>>>>> static u32 msrs_to_save[] = { >>>>>>>>> MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK, >>>>>>>>> MSR_KVM_SYSTEM_TIME_NEW, MSR_KVM_WALL_CLOCK_NEW, >>>>>>>>> - HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL, >>>>>>>>> + HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL, HV_X64_MSR_TIME_REF_COUNT, >>>>>>>>> HV_X64_MSR_APIC_ASSIST_PAGE, MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME, >>>>>>>>> MSR_KVM_PV_EOI_EN, >>>>>>>>> MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP, >>>>>>>>> @@ -1826,6 +1826,8 @@ static bool kvm_hv_msr_partition_wide(u32 msr) >>>>>>>>> switch (msr) { >>>>>>>>> case HV_X64_MSR_GUEST_OS_ID: >>>>>>>>> case HV_X64_MSR_HYPERCALL: >>>>>>>>> + case HV_X64_MSR_REFERENCE_TSC: >>>>>>>>> + case HV_X64_MSR_TIME_REF_COUNT: >>>>>>>>> r = true; >>>>>>>>> break; >>>>>>>>> } >>>>>>>>> @@ -1865,6 +1867,29 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data) >>>>>>>>> if (__copy_to_user((void __user *)addr, instructions, 4)) >>>>>>>>> return 1; >>>>>>>>> kvm->arch.hv_hypercall = data; >>>>>>>>> + local_irq_disable(); >>>>>>>>> + kvm->arch.hv_ref_count = get_kernel_ns() + kvm->arch.kvmclock_offset; >>>>>>>>> + local_irq_enable(); >>>>>>>> >>>>>>>> Where does the docs say that HV_X64_MSR_HYPERCALL is the where the clock >>>>>>>> starts counting? >>>>>>>> >>>>>>>> No need to store kvmclock_offset in hv_ref_count? (moreover >>>>>>>> the name is weird, better name would be "hv_ref_start_time". >>>>>>> >>>>>>> Just add kvmclock_offset when reading the values (otherwise you have a >>>>>>> "stale copy" of kvmclock_offset in hv_ref_count). >>>>>>> >>>>>> >>>>>> After some experiments I think we do no need kvm->arch.hv_ref_count at all. >>>>>> >>>>>> I was debugging some weird clockjump issues and I think the problem is that after live migration >>>>>> kvm->arch.hv_ref_count is initialized to 0. Depending on the uptime of the vServer when the >>>>>> hypercall was set up this can lead to series jumps. >>>>>> >>>>>> So I would suggest to completely drop kvm->arch.hv_ref_count. >>>>>> >>>>>> And use simply this in get_msr_hyperv_pw(). >>>>>> >>>>>> case HV_X64_MSR_TIME_REF_COUNT: { >>>>>> data = div_u64(get_kernel_ns() + kvm->arch.kvmclock_offset, 100); >>>>>> break; >>>>>> } >>>>>> >>>>> >>>>> Agreed. It should work as long as we rely on kvmclock_offset. >>>>> Vadim. >>>> >>>> I think we can rely on kvmclock_offset. Had you had a chance to do further testing >>>> during the weekend? >>> >>> Yes, and still testing. >>> >>> There is still some inconsistency in the value returned by >>> QueryPerformanceCounter during migration. >> >> With my proposal? >> > > Right. > Please see below QTC vs. NTP time stamp > before and after migration: > > C:\timedrift\objchk_win7_x86\i386>timedrift.exe > quantum = 15 > QPC NTP Delta > 1311 1307 4 > 2621 2618 3 > 3932 3931 1 > ....... > ....... > 38018 38014 4 > Unable to wait for NTP reply from the SNTP server, GetLastError returns > 7279088 > 142210 40113 102097 > 143458 41357 102101 > ....... > ....... > 156500 54615 101885 > > NTP time changed from 38014 to 40113 ((40113 - 38014) / 100 = 21 mSec) > while QPC jumped from 38018 to 142210 ((142210 - 38014) / 100 = 1042 > mSec) How long was the downtime when you migrated the vServer? I have done similar tests and have not seen this... Can you show the relevant parts of your patch. Remember I use the REFERENCE_COUTNER not iTSC. Peter