Re: [RFC PATCH 1/2] Hyper-H reference counter

Eric Northup
2013-05-13T23:30:06Z

On Mon, May 13, 2013 at 4:45 AM, Vadim Rozenfeld <vrozenfe@redhat.com> wrote:
> Signed-off: Peter Lieven <pl@dlh.net>
> Signed-off: Gleb Natapov <gleb@redhat.com>
> Signed-off: Vadim Rozenfeld <vrozenfe@redhat.com>
>
> 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?

> + return 1;
> + kvm->arch.hv_tsc_page = data;
> break;
> }
> default:
> @@ -2229,6 +2246,12 @@ static int get_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
> case HV_X64_MSR_HYPERCALL:
> data = kvm->arch.hv_hypercall;
> break;
> + case HV_X64_MSR_TIME_REF_COUNT:
> + data = div_u64(get_kernel_ns() - kvm->arch.hv_ref_count,100);
> + break;
> + case HV_X64_MSR_REFERENCE_TSC:
> + data = kvm->arch.hv_tsc_page;
> + break;
> default:
> vcpu_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
> return 1;
> --
> 1.8.1.2
>
> --
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