Re: [Xen-devel] [PATCH 12/13] vmx: Add a call-back to apply TSC scaling ratio to hardware

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 09/28/2015 03:13 AM, Haozhong Zhang wrote:
> This patch adds a new call-back setup_tsc_scaling in struct
> hvm_function_table to apply the TSC scaling ratio to hardware. For VMX,
> it writes the TSC scaling ratio to VMCS field TSC_MULTIPLIER.
>
> Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
> ---
>   xen/arch/x86/hvm/hvm.c        | 1 +
>   xen/arch/x86/hvm/svm/svm.c    | 5 +++++
>   xen/arch/x86/hvm/vmx/vmx.c    | 8 ++++++++
>   xen/include/asm-x86/hvm/hvm.h | 3 +++
>   4 files changed, 17 insertions(+)
>
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 3522d20..2d8a148 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -376,6 +376,7 @@ void hvm_setup_tsc_scaling(struct vcpu *v)
>       }
>   
>       v->arch.tsc_scaling_ratio = ratio;
> +    hvm_funcs.setup_tsc_scaling(v);
>   }
>   
>   void hvm_set_guest_tsc_fixed(struct vcpu *v, u64 guest_tsc, u64 at_tsc)
> diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
> index 73bc863..d890c1f 100644
> --- a/xen/arch/x86/hvm/svm/svm.c
> +++ b/xen/arch/x86/hvm/svm/svm.c
> @@ -2236,6 +2236,10 @@ static void svm_invlpg_intercept(unsigned long vaddr)
>       svm_asid_g_invlpg(curr, vaddr);
>   }
>   
> +static void svm_setup_tsc_scaling(struct vcpu *v)
> +{
> +}
> +
Should this be wrmsrl(MSR_AMD64_TSC_RATIO, v->arch.tsc_scaling_ratio) ?

-boris

>   static struct hvm_function_table __initdata svm_function_table = {
>       .name                 = "SVM",
>       .cpu_up_prepare       = svm_cpu_up_prepare,
> @@ -2289,6 +2293,7 @@ static struct hvm_function_table __initdata 
> svm_function_table = {
>       .max_tsc_scaling_ratio       = MAX_TSC_RATIO,
>       .tsc_scaling_ratio_frac_bits = 32,
>       .tsc_scaling_ratio_rsvd      = TSC_RATIO_RSVD_BITS,
> +    .setup_tsc_scaling           = svm_setup_tsc_scaling,
>   };
>   
>   void svm_vmexit_handler(struct cpu_user_regs *regs)
> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> index 163974d..c4a7b81 100644
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -1100,6 +1100,13 @@ static void vmx_handle_cd(struct vcpu *v, unsigned long 
> value)
>       }
>   }
>   
> +static void vmx_setup_tsc_scaling(struct vcpu *v)
> +{
> +    vmx_vmcs_enter(v);
> +    __vmwrite(TSC_MULTIPLIER, v->arch.tsc_scaling_ratio);
> +    vmx_vmcs_exit(v);
> +}
> +
>   static void vmx_set_tsc_offset(struct vcpu *v, u64 offset, u64 at_tsc)
>   {
>       uint64_t host_tsc, guest_tsc;
> @@ -1986,6 +1993,7 @@ static struct hvm_function_table __initdata 
> vmx_function_table = {
>       .max_tsc_scaling_ratio       = VMX_TSC_MULTIPLIER_MAX,
>       .tsc_scaling_ratio_frac_bits = 48,
>       .tsc_scaling_ratio_rsvd      = 0x0ULL,
> +    .setup_tsc_scaling           = vmx_setup_tsc_scaling,
>   };
>   
>   const struct hvm_function_table * __init start_vmx(void)
> diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
> index f63fe93..9f8b6d5 100644
> --- a/xen/include/asm-x86/hvm/hvm.h
> +++ b/xen/include/asm-x86/hvm/hvm.h
> @@ -226,6 +226,9 @@ struct hvm_function_table {
>       void (*altp2m_vcpu_update_vmfunc_ve)(struct vcpu *v);
>       bool_t (*altp2m_vcpu_emulate_ve)(struct vcpu *v);
>       int (*altp2m_vcpu_emulate_vmfunc)(struct cpu_user_regs *regs);
> +
> +    /* setup TSC scaling */
> +    void (*setup_tsc_scaling)(struct vcpu *v);
>   };
>   
>   extern struct hvm_function_table hvm_funcs;

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