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

[Boris Ostrovsky]

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.zh...@intel.com>
---
  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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