[v2,3/3] KVM: SVM: add migration support for nested TSC scaling

Commit Message

Maxim Levitsky Nov. 1, 2021, 1:23 p.m. UTC

Signed-off-by: Maxim Levitsky <[e-mail]>
---
 target/i386/cpu.c     |  5 +++++
 target/i386/cpu.h     |  4 ++++
 target/i386/kvm/kvm.c | 15 +++++++++++++++
 target/i386/machine.c | 23 +++++++++++++++++++++++
 4 files changed, 47 insertions(+)

Comments

Paolo Bonzini Nov. 2, 2021, 10:38 a.m. UTC | #1

On 01/11/21 14:23, Maxim Levitsky wrote:
> Signed-off-by: Maxim Levitsky <[e-mail]>
> ---
>   target/i386/cpu.c     |  5 +++++
>   target/i386/cpu.h     |  4 ++++
>   target/i386/kvm/kvm.c | 15 +++++++++++++++
>   target/i386/machine.c | 23 +++++++++++++++++++++++
>   4 files changed, 47 insertions(+)

It's easier to migrate it unconditionally:

diff --git a/target/i386/machine.c b/target/i386/machine.c
index e1138693f3..83c2b91529 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -1286,8 +1286,7 @@ static bool amd_tsc_scale_msr_needed(void *opaque)
      X86CPU *cpu = opaque;
      CPUX86State *env = &cpu->env;

-    return env->amd_tsc_scale_msr &&
-           env->amd_tsc_scale_msr != MSR_AMD64_TSC_RATIO_DEFAULT;
+    return (env->features[FEAT_SVM] & CPUID_SVM_TSCSCALE);
  }

  static const VMStateDescription amd_tsc_scale_msr_ctrl = {

> +    if (env->features[FEAT_SVM] & CPUID_SVM_TSCSCALE) {
> +        env->amd_tsc_scale_msr =  MSR_AMD64_TSC_RATIO_DEFAULT;
> +    }

and also set it unconditionally here, so that it's always passed 
correctly to KVM.

I queued patches 2 and 3, for (1) I need to think more about migration 
to older QEMU versions.

Paolo

Patch

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 598d451dcf..53a23ca006 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5928,6 +5928,11 @@  static void x86_cpu_reset(DeviceState *dev)
     }
 
     x86_cpu_set_sgxlepubkeyhash(env);
+
+    if (env->features[FEAT_SVM] & CPUID_SVM_TSCSCALE) {
+        env->amd_tsc_scale_msr =  MSR_AMD64_TSC_RATIO_DEFAULT;
+    }
+
 #endif
 }
 
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 8c39e787f9..9911d7c871 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -499,6 +499,9 @@  typedef enum X86Seg {
 #define MSR_GSBASE                      0xc0000101
 #define MSR_KERNELGSBASE                0xc0000102
 #define MSR_TSC_AUX                     0xc0000103
+#define MSR_AMD64_TSC_RATIO             0xc0000104
+
+#define MSR_AMD64_TSC_RATIO_DEFAULT     0x100000000ULL
 
 #define MSR_VM_HSAVE_PA                 0xc0010117
 
@@ -1539,6 +1542,7 @@  typedef struct CPUX86State {
     uint32_t tsx_ctrl;
 
     uint64_t spec_ctrl;
+    uint64_t amd_tsc_scale_msr;
     uint64_t virt_ssbd;
 
     /* End of state preserved by INIT (dummy marker).  */
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 13be6995a8..e2dad8e168 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -105,6 +105,7 @@  static bool has_msr_hv_reenlightenment;
 static bool has_msr_xss;
 static bool has_msr_umwait;
 static bool has_msr_spec_ctrl;
+static bool has_tsc_scale_msr;
 static bool has_msr_tsx_ctrl;
 static bool has_msr_virt_ssbd;
 static bool has_msr_smi_count;
@@ -2216,6 +2217,9 @@  static int kvm_get_supported_msrs(KVMState *s)
             case MSR_IA32_SPEC_CTRL:
                 has_msr_spec_ctrl = true;
                 break;
+            case MSR_AMD64_TSC_RATIO:
+                has_tsc_scale_msr = true;
+                break;
             case MSR_IA32_TSX_CTRL:
                 has_msr_tsx_ctrl = true;
                 break;
@@ -3027,6 +3031,10 @@  static int kvm_put_msrs(X86CPU *cpu, int level)
     if (has_msr_spec_ctrl) {
         kvm_msr_entry_add(cpu, MSR_IA32_SPEC_CTRL, env->spec_ctrl);
     }
+    if (has_tsc_scale_msr) {
+        kvm_msr_entry_add(cpu, MSR_AMD64_TSC_RATIO, env->amd_tsc_scale_msr);
+    }
+
     if (has_msr_tsx_ctrl) {
         kvm_msr_entry_add(cpu, MSR_IA32_TSX_CTRL, env->tsx_ctrl);
     }
@@ -3479,6 +3487,10 @@  static int kvm_get_msrs(X86CPU *cpu)
     if (has_msr_spec_ctrl) {
         kvm_msr_entry_add(cpu, MSR_IA32_SPEC_CTRL, 0);
     }
+    if (has_tsc_scale_msr) {
+        kvm_msr_entry_add(cpu, MSR_AMD64_TSC_RATIO, 0);
+    }
+
     if (has_msr_tsx_ctrl) {
         kvm_msr_entry_add(cpu, MSR_IA32_TSX_CTRL, 0);
     }
@@ -3890,6 +3902,9 @@  static int kvm_get_msrs(X86CPU *cpu)
         case MSR_IA32_SPEC_CTRL:
             env->spec_ctrl = msrs[i].data;
             break;
+        case MSR_AMD64_TSC_RATIO:
+            env->amd_tsc_scale_msr = msrs[i].data;
+            break;
         case MSR_IA32_TSX_CTRL:
             env->tsx_ctrl = msrs[i].data;
             break;
diff --git a/target/i386/machine.c b/target/i386/machine.c
index 14dd5ed79c..5dea1ef30d 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -1280,6 +1280,28 @@  static const VMStateDescription vmstate_spec_ctrl = {
     }
 };
 
+
+static bool amd_tsc_scale_msr_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->amd_tsc_scale_msr &&
+           env->amd_tsc_scale_msr != MSR_AMD64_TSC_RATIO_DEFAULT;
+}
+
+static const VMStateDescription amd_tsc_scale_msr_ctrl = {
+    .name = "cpu/amd_tsc_scale_msr",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = amd_tsc_scale_msr_needed,
+    .fields = (VMStateField[]){
+        VMSTATE_UINT64(env.amd_tsc_scale_msr, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+
 static bool intel_pt_enable_needed(void *opaque)
 {
     X86CPU *cpu = opaque;
@@ -1586,6 +1608,7 @@  const VMStateDescription vmstate_x86_cpu = {
         &vmstate_pkru,
         &vmstate_pkrs,
         &vmstate_spec_ctrl,
+        &amd_tsc_scale_msr_ctrl,
         &vmstate_mcg_ext_ctl,
         &vmstate_msr_intel_pt,
         &vmstate_msr_virt_ssbd,