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 11:15:47 +0100 Message-ID: <52CD2553.60903@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> 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]:47820 "EHLO ssl.dlhnet.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754927AbaAHKOM (ORCPT ); Wed, 8 Jan 2014 05:14:12 -0500 In-Reply-To: <1389174021.9714.7.camel@localhost> Sender: kvm-owner@vger.kernel.org List-ID: 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? Peter