From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vadim Rozenfeld Subject: Re: [RFC PATCH 1/2] Hyper-H reference counter Date: Thu, 16 May 2013 18:53:07 +1000 Message-ID: <1368694387.18400.1.camel@localhost> References: <1368445517-5496-1-git-send-email-vrozenfe@redhat.com> <1368445517-5496-2-git-send-email-vrozenfe@redhat.com> <1368524796.7956.19.camel@localhost> <20130516081807.GK26453@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Eric Northup , KVM , Marcelo Tosatti , pl@dlh.net To: Gleb Natapov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:2663 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755427Ab3EPIxT (ORCPT ); Thu, 16 May 2013 04:53:19 -0400 In-Reply-To: <20130516081807.GK26453@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, 2013-05-16 at 11:18 +0300, Gleb Natapov wrote: > On Tue, May 14, 2013 at 07:46:36PM +1000, Vadim Rozenfeld wrote: > > On Mon, 2013-05-13 at 16:30 -0700, Eric Northup wrote: > > > On Mon, May 13, 2013 at 4:45 AM, Vadim Rozenfeld wrote: > > > > Signed-off: Peter Lieven > > > > Signed-off: Gleb Natapov > > > > Signed-off: Vadim Rozenfeld > > > > > > > > The following patch allows to activate Hyper-V > > > > reference time counter > > > > --- > > > > arch/x86/include/asm/kvm_host.h | 2 ++ > > > > arch/x86/include/uapi/asm/hyperv.h | 3 +++ > > > > arch/x86/kvm/x86.c | 25 ++++++++++++++++++++++++- > > > > 3 files changed, 29 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > > > index 3741c65..f0fee35 100644 > > > > --- a/arch/x86/include/asm/kvm_host.h > > > > +++ b/arch/x86/include/asm/kvm_host.h > > > > @@ -575,6 +575,8 @@ 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 b80420b..9711819 100644 > > > > --- a/arch/x86/include/uapi/asm/hyperv.h > > > > +++ b/arch/x86/include/uapi/asm/hyperv.h > > > > @@ -136,6 +136,9 @@ > > > > /* MSR used to read the per-partition time reference counter */ > > > > #define HV_X64_MSR_TIME_REF_COUNT 0x40000020 > > > > > > > > +/* A partition's reference time stamp counter (TSC) page */ > > > > +#define HV_X64_MSR_REFERENCE_TSC 0x40000021 > > > > + > > > > /* Define the virtual APIC registers */ > > > > #define HV_X64_MSR_EOI 0x40000070 > > > > #define HV_X64_MSR_ICR 0x40000071 > > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > > > index 094b5d9..1a4036d 100644 > > > > --- a/arch/x86/kvm/x86.c > > > > +++ b/arch/x86/kvm/x86.c > > > > @@ -843,7 +843,7 @@ 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, > > > > @@ -1764,6 +1764,8 @@ 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; > > > > } > > > > @@ -1803,6 +1805,21 @@ 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; > > > > + kvm->arch.hv_ref_count = get_kernel_ns(); > > > > + break; > > > > + } > > > > + case HV_X64_MSR_REFERENCE_TSC: { > > > > + u64 gfn; > > > > + unsigned long addr; > > > > + u32 tsc_ref; > > > > + gfn = data >> HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT; > > > > + addr = gfn_to_hva(kvm, gfn); > > > > + if (kvm_is_error_hva(addr)) > > > > + return 1; > > > > + tsc_ref = 0; > > > > + if(__copy_to_user((void __user *)addr, &tsc_ref, sizeof(tsc_ref))) > > > > > > Does this do the right thing when we're migrating? How does usermode > > > learn that the guest page has been dirtied? > > > > > > > No, it shouldn't be a problem for this patch. Guest allocates a page > > from nonpaged physical memory, maps it to the system address space, gets > > physical address and sends it to KVM. KVM sets the first DWORD > > (TscSequence) to zero, which means that guest will use reference time > > counter as a timestamp source even after migration. > > > Eric is right, we need mark_page_dirty() here and in HV_X64_MSR_HYPERCALL > too. Without it QEMU will not know that content of the page has changed > and will not migrate it. OK. Will fix it. > > -- > Gleb.