Re: [RFC PATCH 2/2] Hyper-V iTSC handler

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On Mon, May 13, 2013 at 09:45:17PM +1000, Vadim Rozenfeld wrote:
> Signed-off: Vadim Rozenfeld <vrozenfe@xxxxxxxxxx>
> 
> The following patch allows to activate a partition reference 
> time enlightenment that is based on the host platform's support 
> for an Invariant Time Stamp Counter (iTSC).
> NOTE: This code will survive migration due to lack of VM stop/resume
> handlers.
> 
Do you mean "will _not_ survive migration"?

> ---
>  arch/x86/include/uapi/asm/hyperv.h | 10 ++++++++++
>  arch/x86/kvm/x86.c                 | 18 +++++++++++++-----
>  include/uapi/linux/kvm.h           |  1 +
>  3 files changed, 24 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
> index 9711819..2d9e666 100644
> --- a/arch/x86/include/uapi/asm/hyperv.h
> +++ b/arch/x86/include/uapi/asm/hyperv.h
> @@ -182,6 +182,9 @@
>  #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
> @@ -194,4 +197,11 @@
>  #define HV_STATUS_INVALID_ALIGNMENT		4
>  #define HV_STATUS_INSUFFICIENT_BUFFERS		19
>  
> +typedef struct _HV_REFERENCE_TSC_PAGE {
> +	uint32_t TscSequence;
> +	uint32_t Rserved1;
> +	uint64_t TscScale;
> +	int64_t  TscOffset;
> +} HV_REFERENCE_TSC_PAGE, * PHV_REFERENCE_TSC_PAGE;
> +
Use kernel types: __u32/__u64/__s64.

>  #endif
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 1a4036d..5788e8f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1809,14 +1809,21 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
>  		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);
> +		HV_REFERENCE_TSC_PAGE tsc_ref;
> +		tsc_ref.TscSequence =
> +			boot_cpu_has(X86_FEATURE_CONSTANT_TSC) ? 1 : 0;
> +		tsc_ref.TscScale =
> +			((10000LL << 32) /vcpu->arch.virtual_tsc_khz) << 32;
> +		tsc_ref.TscOffset = 0;
> +		if (!(data & HV_X64_MSR_TSC_REFERENCE_ENABLE)) {
> +			kvm->arch.hv_tsc_page = data;
> +			break;
> +		}
> +		addr = gfn_to_hva(vcpu->kvm, data >>
> +			HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT);
>  		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;
> @@ -2553,6 +2560,7 @@ int kvm_dev_ioctl_check_extension(long ext)
>  	case KVM_CAP_HYPERV:
>  	case KVM_CAP_HYPERV_VAPIC:
>  	case KVM_CAP_HYPERV_SPIN:
> +	case KVM_CAP_HYPERV_TSC:
>  	case KVM_CAP_PCI_SEGMENT:
>  	case KVM_CAP_DEBUGREGS:
>  	case KVM_CAP_X86_ROBUST_SINGLESTEP:
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index a5c86fc..8eff540 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -666,6 +666,7 @@ struct kvm_ppc_smmu_info {
>  #define KVM_CAP_IRQ_MPIC 90
>  #define KVM_CAP_PPC_RTAS 91
>  #define KVM_CAP_IRQ_XICS 92
> +#define KVM_CAP_HYPERV_TSC 93
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>  
> -- 
> 1.8.1.2

--
			Gleb.
--
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