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

[Vadim Rozenfeld <vrozenfe@redhat.com>]

On Thu, 2013-05-16 at 15:44 +0200, Paolo Bonzini wrote:
> Il 16/05/2013 11:28, Vadim Rozenfeld ha scritto:
> > On Thu, 2013-05-16 at 12:21 +0300, Gleb Natapov wrote:
> >> On Thu, May 16, 2013 at 07:13:41PM +1000, Vadim Rozenfeld wrote:
> >>> On Thu, 2013-05-16 at 11:34 +0300, Gleb Natapov wrote:
> >>>> On Mon, May 13, 2013 at 09:45:16PM +1000, Vadim Rozenfeld 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();
> 
> Please rename to kvm->arch.hv_ref_count_base.
> 
> >>>>> +		break;
> >>>>> +	}
> >>>>> +	case HV_X64_MSR_REFERENCE_TSC: {
> >>>>> +		u64 gfn;
> >>>>> +		unsigned long addr;
> >>>>> +		u32 tsc_ref;
> >>>>> +		gfn = data >> HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT;
> >>>> Shouldn't you check HV_X64_MSR_TSC_REFERENCE_ENABLE here?
> >>>
> >>> Yes, I have this check added in the second patch.
> >>>
> >> Move it here please.
> > OK, will do it.
> 
> Or better, remove all the handling of HV_X64_MSR_REFERENCE_TSC from this
> patch, and leave it all to the second.
> 

What for? Could you please elaborate?
Vadim. 

> Paolo
> 
> >>>>
> >>>>> +		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)))
> >>>>> +			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
> >>>>
> >>>> --
> >>>> 			Gleb.
> >>>
> >>
> >> --
> >> 			Gleb.
> > 
> > 
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