kvm: i386: halt poll control MSR support

PATCH Applied Marcelo Tosatti 3 participants 6 messages Jun 3, 2019 – Jul 16, 2019 KVM

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Marcelo Tosatti

author

2019-06-03 23:04 UTC #0 lore raw

PATCH 1/1 kvm: i386: halt poll control MSR support

(CC'ing qemu devel)

Add support for halt poll control MSR: save/restore, migration and new feature name.

The purpose of this MSR is to allow the guest to disable host halt poll.

Signed-off-by Marcelo Tosatti <[email protected]>

include/standard-headers/asm-x86/kvm_para.h +2 -0

index 35cd8d6..e171514 100644
@@ -29,6 +29,7 @@
 #define KVM_FEATURE_PV_TLB_FLUSH	9
 #define KVM_FEATURE_ASYNC_PF_VMEXIT	10
 #define KVM_FEATURE_PV_SEND_IPI	11
+#define KVM_FEATURE_POLL_CONTROL	12
 
 #define KVM_HINTS_REALTIME      0

@@ -47,6 +48,7 @@
 #define MSR_KVM_ASYNC_PF_EN 0x4b564d02
 #define MSR_KVM_STEAL_TIME  0x4b564d03
 #define MSR_KVM_PV_EOI_EN      0x4b564d04
+#define MSR_KVM_POLL_CONTROL	0x4b564d05
 
 struct kvm_steal_time {
 	uint64_t steal;

target/i386/cpu.c +4 -1

index c1ab86d..1ca6944 100644
@@ -903,7 +903,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             "kvmclock", "kvm-nopiodelay", "kvm-mmu", "kvmclock",
             "kvm-asyncpf", "kvm-steal-time", "kvm-pv-eoi", "kvm-pv-unhalt",
             NULL, "kvm-pv-tlb-flush", NULL, "kvm-pv-ipi",
-            NULL, NULL, NULL, NULL,
+            "kvm-poll-control", NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             "kvmclock-stable-bit", NULL, NULL, NULL,

@@ -3001,6 +3001,7 @@ static PropValue kvm_default_props[] = {
     { "kvm-asyncpf", "on" },
     { "kvm-steal-time", "on" },
     { "kvm-pv-eoi", "on" },
+    { "kvm-poll-control", "on" },
     { "kvmclock-stable-bit", "on" },
     { "x2apic", "on" },
     { "acpi", "off" },

@@ -5660,6 +5661,8 @@ static void x86_cpu_initfn(Object *obj)
     object_property_add_alias(obj, "kvm_steal_time", obj, "kvm-steal-time", &error_abort);
     object_property_add_alias(obj, "kvm_pv_eoi", obj, "kvm-pv-eoi", &error_abort);
     object_property_add_alias(obj, "kvm_pv_unhalt", obj, "kvm-pv-unhalt", &error_abort);
+    object_property_add_alias(obj, "kvm_poll_control", obj, "kvm-poll-control",
+                              &error_abort);
     object_property_add_alias(obj, "svm_lock", obj, "svm-lock", &error_abort);
     object_property_add_alias(obj, "nrip_save", obj, "nrip-save", &error_abort);
     object_property_add_alias(obj, "tsc_scale", obj, "tsc-scale", &error_abort);

target/i386/cpu.h +1 -0

index bd06523..21ed2f8 100644
@@ -1241,6 +1241,7 @@ typedef struct CPUX86State {
     uint64_t steal_time_msr;
     uint64_t async_pf_en_msr;
     uint64_t pv_eoi_en_msr;
+    uint64_t poll_control_msr;
 
     /* Partition-wide HV MSRs, will be updated only on the first vcpu */
     uint64_t msr_hv_hypercall;

target/i386/kvm.c +14 -0

index 3b29ce5..a5e9cdf 100644
@@ -1369,6 +1369,8 @@ void kvm_arch_reset_vcpu(X86CPU *cpu)
 
         hyperv_x86_synic_reset(cpu);
     }
+    /* enabled by default */
+    env->poll_control_msr = 1;
 }
 
 void kvm_arch_do_init_vcpu(X86CPU *cpu)

@@ -2059,6 +2061,11 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
         if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) {
             kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, env->steal_time_msr);
         }
+
+        if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_POLL_CONTROL)) {
+            kvm_msr_entry_add(cpu, MSR_KVM_POLL_CONTROL, env->poll_control_msr);
+        }
+
         if (has_architectural_pmu_version > 0) {
             if (has_architectural_pmu_version > 1) {
                 /* Stop the counter.  */

@@ -2443,6 +2450,9 @@ static int kvm_get_msrs(X86CPU *cpu)
     if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) {
         kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, 0);
     }
+    if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_POLL_CONTROL)) {
+        kvm_msr_entry_add(cpu, MSR_KVM_POLL_CONTROL, 1);
+    }
     if (has_architectural_pmu_version > 0) {
         if (has_architectural_pmu_version > 1) {
             kvm_msr_entry_add(cpu, MSR_CORE_PERF_FIXED_CTR_CTRL, 0);

@@ -2677,6 +2687,10 @@ static int kvm_get_msrs(X86CPU *cpu)
         case MSR_KVM_STEAL_TIME:
             env->steal_time_msr = msrs[i].data;
             break;
+        case MSR_KVM_POLL_CONTROL: {
+            env->poll_control_msr = msrs[i].data;
+            break;
+        }
         case MSR_CORE_PERF_FIXED_CTR_CTRL:
             env->msr_fixed_ctr_ctrl = msrs[i].data;
             break;

target/i386/machine.c +20 -0

index 225b5d4..1c23e5e 100644
@@ -323,6 +323,14 @@ static bool steal_time_msr_needed(void *opaque)
     return cpu->env.steal_time_msr != 0;
 }
 
+/* Poll control MSR enabled by default */
+static bool poll_control_msr_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+
+    return cpu->env.poll_control_msr != 1;
+}
+
 static const VMStateDescription vmstate_steal_time_msr = {
     .name = "cpu/steal_time_msr",
     .version_id = 1,

@@ -356,6 +364,17 @@ static const VMStateDescription vmstate_pv_eoi_msr = {
     }
 };
 
+static const VMStateDescription vmstate_poll_control_msr = {
+    .name = "cpu/poll_control_msr",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = poll_control_msr_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.poll_control_msr, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static bool fpop_ip_dp_needed(void *opaque)
 {
     X86CPU *cpu = opaque;

@@ -1062,6 +1081,7 @@ VMStateDescription vmstate_x86_cpu = {
         &vmstate_async_pf_msr,
         &vmstate_pv_eoi_msr,
         &vmstate_steal_time_msr,
+        &vmstate_poll_control_msr,
         &vmstate_fpop_ip_dp,
         &vmstate_msr_tsc_adjust,
         &vmstate_msr_tscdeadline,

Paolo Bonzini

maintainer Applied

2019-07-15 09:23 UTC #1 lore raw

Quoted 157 lines · Marcelo Tosatti

(CC'ing qemu devel)

Add support for halt poll control MSR: save/restore, migration and new feature name.

The purpose of this MSR is to allow the guest to disable host halt poll.

Signed-off-by Marcelo Tosatti <[email protected]>

include/standard-headers/asm-x86/kvm_para.h +2 -0

index 35cd8d6..e171514 100644
@@ -29,6 +29,7 @@
 #define KVM_FEATURE_PV_TLB_FLUSH	9
 #define KVM_FEATURE_ASYNC_PF_VMEXIT	10
 #define KVM_FEATURE_PV_SEND_IPI	11
+#define KVM_FEATURE_POLL_CONTROL	12
 
 #define KVM_HINTS_REALTIME      0

@@ -47,6 +48,7 @@
 #define MSR_KVM_ASYNC_PF_EN 0x4b564d02
 #define MSR_KVM_STEAL_TIME  0x4b564d03
 #define MSR_KVM_PV_EOI_EN      0x4b564d04
+#define MSR_KVM_POLL_CONTROL	0x4b564d05
 
 struct kvm_steal_time {
 	uint64_t steal;

target/i386/cpu.c +4 -1

index c1ab86d..1ca6944 100644
@@ -903,7 +903,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             "kvmclock", "kvm-nopiodelay", "kvm-mmu", "kvmclock",
             "kvm-asyncpf", "kvm-steal-time", "kvm-pv-eoi", "kvm-pv-unhalt",
             NULL, "kvm-pv-tlb-flush", NULL, "kvm-pv-ipi",
-            NULL, NULL, NULL, NULL,
+            "kvm-poll-control", NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             "kvmclock-stable-bit", NULL, NULL, NULL,

@@ -3001,6 +3001,7 @@ static PropValue kvm_default_props[] = {
     { "kvm-asyncpf", "on" },
     { "kvm-steal-time", "on" },
     { "kvm-pv-eoi", "on" },
+    { "kvm-poll-control", "on" },
     { "kvmclock-stable-bit", "on" },
     { "x2apic", "on" },
     { "acpi", "off" },

@@ -5660,6 +5661,8 @@ static void x86_cpu_initfn(Object *obj)
     object_property_add_alias(obj, "kvm_steal_time", obj, "kvm-steal-time", &error_abort);
     object_property_add_alias(obj, "kvm_pv_eoi", obj, "kvm-pv-eoi", &error_abort);
     object_property_add_alias(obj, "kvm_pv_unhalt", obj, "kvm-pv-unhalt", &error_abort);
+    object_property_add_alias(obj, "kvm_poll_control", obj, "kvm-poll-control",
+                              &error_abort);
     object_property_add_alias(obj, "svm_lock", obj, "svm-lock", &error_abort);
     object_property_add_alias(obj, "nrip_save", obj, "nrip-save", &error_abort);
     object_property_add_alias(obj, "tsc_scale", obj, "tsc-scale", &error_abort);

target/i386/cpu.h +1 -0

index bd06523..21ed2f8 100644
@@ -1241,6 +1241,7 @@ typedef struct CPUX86State {
     uint64_t steal_time_msr;
     uint64_t async_pf_en_msr;
     uint64_t pv_eoi_en_msr;
+    uint64_t poll_control_msr;
 
     /* Partition-wide HV MSRs, will be updated only on the first vcpu */
     uint64_t msr_hv_hypercall;

target/i386/kvm.c +14 -0

index 3b29ce5..a5e9cdf 100644
@@ -1369,6 +1369,8 @@ void kvm_arch_reset_vcpu(X86CPU *cpu)
 
         hyperv_x86_synic_reset(cpu);
     }
+    /* enabled by default */
+    env->poll_control_msr = 1;
 }
 
 void kvm_arch_do_init_vcpu(X86CPU *cpu)

@@ -2059,6 +2061,11 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
         if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) {
             kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, env->steal_time_msr);
         }
+
+        if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_POLL_CONTROL)) {
+            kvm_msr_entry_add(cpu, MSR_KVM_POLL_CONTROL, env->poll_control_msr);
+        }
+
         if (has_architectural_pmu_version > 0) {
             if (has_architectural_pmu_version > 1) {
                 /* Stop the counter.  */

@@ -2443,6 +2450,9 @@ static int kvm_get_msrs(X86CPU *cpu)
     if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) {
         kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, 0);
     }
+    if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_POLL_CONTROL)) {
+        kvm_msr_entry_add(cpu, MSR_KVM_POLL_CONTROL, 1);
+    }
     if (has_architectural_pmu_version > 0) {
         if (has_architectural_pmu_version > 1) {
             kvm_msr_entry_add(cpu, MSR_CORE_PERF_FIXED_CTR_CTRL, 0);

@@ -2677,6 +2687,10 @@ static int kvm_get_msrs(X86CPU *cpu)
         case MSR_KVM_STEAL_TIME:
             env->steal_time_msr = msrs[i].data;
             break;
+        case MSR_KVM_POLL_CONTROL: {
+            env->poll_control_msr = msrs[i].data;
+            break;
+        }
         case MSR_CORE_PERF_FIXED_CTR_CTRL:
             env->msr_fixed_ctr_ctrl = msrs[i].data;
             break;

target/i386/machine.c +19 -0

index 225b5d4..1c23e5e 100644
@@ -323,6 +323,14 @@ static bool steal_time_msr_needed(void *opaque)
     return cpu->env.steal_time_msr != 0;
 }
 
+/* Poll control MSR enabled by default */
+static bool poll_control_msr_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+
+    return cpu->env.poll_control_msr != 1;
+}
+
 static const VMStateDescription vmstate_steal_time_msr = {
     .name = "cpu/steal_time_msr",
     .version_id = 1,

@@ -356,6 +364,17 @@ static const VMStateDescription vmstate_pv_eoi_msr = {
     }
 };
 
+static const VMStateDescription vmstate_poll_control_msr = {
+    .name = "cpu/poll_control_msr",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = poll_control_msr_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.poll_control_msr, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static bool fpop_ip_dp_needed(void *opaque)
 {
     X86CPU *cpu = opaque;

target/i386/machine.c VMStateDescription vmstate_x86_cpu = { · line 1087

Quoted 7 lines

target/i386/machine.c +1 -0

@@ -1062,6 +1081,7 @@ VMStateDescription vmstate_x86_cpu = {
         &vmstate_async_pf_msr,
         &vmstate_pv_eoi_msr,
         &vmstate_steal_time_msr,
+        &vmstate_poll_control_msr,
         &vmstate_fpop_ip_dp,
         &vmstate_msr_tsc_adjust,
         &vmstate_msr_tscdeadline,

Queued, thanks. Sorry for missing it until now.

Paolo

Mark Kanda

2019-07-16 19:54 UTC #2 lore raw

Hi all,

If the host doesn't support halt polling, this patch seems to break libvirt save/restore:

"
virsh # save halt-poll-vm halt-poll-vm.sav --running --verbose
Save: [100 %]
Domain halt-poll-vm saved to halt-poll-vm.sav

virsh # restore halt-poll-vm.sav
error: Failed to restore domain from halt-poll-vm.sav
error: operation failed: guest CPU doesn't match specification "

I believe this occurs because libvirt rejects the restore if there are filtered features, which is the case if halt polling is enabled on a host which doesn't support it (halt polling is enabled 'by default').

As such, I think we should only enable halt polling if it is supported on the host - see the attached patch.

...thoughts?

Thanks,
-Mark

Quoted 168 lines · Paolo Bonzini

Quoted 157 lines · Marcelo Tosatti

(CC'ing qemu devel)

Add support for halt poll control MSR: save/restore, migration and new feature name.

The purpose of this MSR is to allow the guest to disable host halt poll.

Signed-off-by Marcelo Tosatti <[email protected]>

include/standard-headers/asm-x86/kvm_para.h +2 -0

index 35cd8d6..e171514 100644
@@ -29,6 +29,7 @@
  #define KVM_FEATURE_PV_TLB_FLUSH	9
  #define KVM_FEATURE_ASYNC_PF_VMEXIT	10
  #define KVM_FEATURE_PV_SEND_IPI	11
+#define KVM_FEATURE_POLL_CONTROL	12
 
  #define KVM_HINTS_REALTIME      0

@@ -47,6 +48,7 @@
  #define MSR_KVM_ASYNC_PF_EN 0x4b564d02
  #define MSR_KVM_STEAL_TIME  0x4b564d03
  #define MSR_KVM_PV_EOI_EN      0x4b564d04
+#define MSR_KVM_POLL_CONTROL	0x4b564d05
 
  struct kvm_steal_time {
  	uint64_t steal;

target/i386/cpu.c +4 -1

index c1ab86d..1ca6944 100644
@@ -903,7 +903,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
              "kvmclock", "kvm-nopiodelay", "kvm-mmu", "kvmclock",
              "kvm-asyncpf", "kvm-steal-time", "kvm-pv-eoi", "kvm-pv-unhalt",
              NULL, "kvm-pv-tlb-flush", NULL, "kvm-pv-ipi",
-            NULL, NULL, NULL, NULL,
+            "kvm-poll-control", NULL, NULL, NULL,
              NULL, NULL, NULL, NULL,
              NULL, NULL, NULL, NULL,
              "kvmclock-stable-bit", NULL, NULL, NULL,

@@ -3001,6 +3001,7 @@ static PropValue kvm_default_props[] = {
      { "kvm-asyncpf", "on" },
      { "kvm-steal-time", "on" },
      { "kvm-pv-eoi", "on" },
+    { "kvm-poll-control", "on" },
      { "kvmclock-stable-bit", "on" },
      { "x2apic", "on" },
      { "acpi", "off" },

@@ -5660,6 +5661,8 @@ static void x86_cpu_initfn(Object *obj)
      object_property_add_alias(obj, "kvm_steal_time", obj, "kvm-steal-time", &error_abort);
      object_property_add_alias(obj, "kvm_pv_eoi", obj, "kvm-pv-eoi", &error_abort);
      object_property_add_alias(obj, "kvm_pv_unhalt", obj, "kvm-pv-unhalt", &error_abort);
+    object_property_add_alias(obj, "kvm_poll_control", obj, "kvm-poll-control",
+                              &error_abort);
      object_property_add_alias(obj, "svm_lock", obj, "svm-lock", &error_abort);
      object_property_add_alias(obj, "nrip_save", obj, "nrip-save", &error_abort);
      object_property_add_alias(obj, "tsc_scale", obj, "tsc-scale", &error_abort);

target/i386/cpu.h +1 -0

index bd06523..21ed2f8 100644
@@ -1241,6 +1241,7 @@ typedef struct CPUX86State {
      uint64_t steal_time_msr;
      uint64_t async_pf_en_msr;
      uint64_t pv_eoi_en_msr;
+    uint64_t poll_control_msr;
 
      /* Partition-wide HV MSRs, will be updated only on the first vcpu */
      uint64_t msr_hv_hypercall;

target/i386/kvm.c +14 -0

index 3b29ce5..a5e9cdf 100644
@@ -1369,6 +1369,8 @@ void kvm_arch_reset_vcpu(X86CPU *cpu)
 
          hyperv_x86_synic_reset(cpu);
      }
+    /* enabled by default */
+    env->poll_control_msr = 1;
  }
 
  void kvm_arch_do_init_vcpu(X86CPU *cpu)

@@ -2059,6 +2061,11 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
          if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) {
              kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, env->steal_time_msr);
          }
+
+        if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_POLL_CONTROL)) {
+            kvm_msr_entry_add(cpu, MSR_KVM_POLL_CONTROL, env->poll_control_msr);
+        }
+
          if (has_architectural_pmu_version > 0) {
              if (has_architectural_pmu_version > 1) {
                  /* Stop the counter.  */

@@ -2443,6 +2450,9 @@ static int kvm_get_msrs(X86CPU *cpu)
      if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) {
          kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, 0);
      }
+    if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_POLL_CONTROL)) {
+        kvm_msr_entry_add(cpu, MSR_KVM_POLL_CONTROL, 1);
+    }
      if (has_architectural_pmu_version > 0) {
          if (has_architectural_pmu_version > 1) {
              kvm_msr_entry_add(cpu, MSR_CORE_PERF_FIXED_CTR_CTRL, 0);

@@ -2677,6 +2687,10 @@ static int kvm_get_msrs(X86CPU *cpu)
          case MSR_KVM_STEAL_TIME:
              env->steal_time_msr = msrs[i].data;
              break;
+        case MSR_KVM_POLL_CONTROL: {
+            env->poll_control_msr = msrs[i].data;
+            break;
+        }
          case MSR_CORE_PERF_FIXED_CTR_CTRL:
              env->msr_fixed_ctr_ctrl = msrs[i].data;
              break;

target/i386/machine.c +19 -0

index 225b5d4..1c23e5e 100644
@@ -323,6 +323,14 @@ static bool steal_time_msr_needed(void *opaque)
      return cpu->env.steal_time_msr != 0;
  }
 
+/* Poll control MSR enabled by default */
+static bool poll_control_msr_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+
+    return cpu->env.poll_control_msr != 1;
+}
+
  static const VMStateDescription vmstate_steal_time_msr = {
      .name = "cpu/steal_time_msr",
      .version_id = 1,

@@ -356,6 +364,17 @@ static const VMStateDescription vmstate_pv_eoi_msr = {
      }
  };
 
+static const VMStateDescription vmstate_poll_control_msr = {
+    .name = "cpu/poll_control_msr",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = poll_control_msr_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.poll_control_msr, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
  static bool fpop_ip_dp_needed(void *opaque)
  {
      X86CPU *cpu = opaque;

target/i386/machine.c VMStateDescription vmstate_x86_cpu = { · line 1087

Quoted 7 lines

target/i386/machine.c +1 -0

@@ -1062,6 +1081,7 @@ VMStateDescription vmstate_x86_cpu = {
          &vmstate_async_pf_msr,
          &vmstate_pv_eoi_msr,
          &vmstate_steal_time_msr,
+        &vmstate_poll_control_msr,
          &vmstate_fpop_ip_dp,
          &vmstate_msr_tsc_adjust,
          &vmstate_msr_tscdeadline,

Queued, thanks. Sorry for missing it until now.

Quoted 3 lines

Paolo

From ac83cb52be3fbe226645e780500adb767f9bcfd2 Mon Sep 17 00:00:00 2001
From: Mark Kanda <[email protected]>
Date: Tue, 16 Jul 2019 14:46:11 -0500
Subject: [PATCH QEMU] Only enable the halt poll control MSR if it is supported
by the host

The halt poll control MSR should only be enabled on hosts which support it.

Fixes ("kvm: i386: halt poll control MSR support")

Signed-off-by Mark Kanda <[email protected]>

---
 target/i386/cpu.c     | 8 +++++++-
 target/i386/kvm.c     | 2 --
 target/i386/machine.c | 1 -
 3 files changed, 7 insertions(+), 4 deletions(-)

target/i386/cpu.c +7 -1

index a8bafdb8b9..dacbf7a9fe 100644
@@ -2838,7 +2838,6 @@ static PropValue kvm_default_props[] = {
     { "kvm-asyncpf", "on" },
     { "kvm-steal-time", "on" },
     { "kvm-pv-eoi", "on" },
-    { "kvm-poll-control", "on" },
     { "kvmclock-stable-bit", "on" },
     { "x2apic", "on" },
     { "acpi", "off" },

@@ -5109,6 +5108,13 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
         env->cpuid_xlevel2 = env->cpuid_min_xlevel2;
     }
 
+    /* Enable the halt poll control MSR if it is supported by the host */
+    if (x86_cpu_get_supported_feature_word(FEAT_KVM, cpu->migratable) &
+        (1 << KVM_FEATURE_POLL_CONTROL)) {
+        env->features[FEAT_KVM] |= 1 << KVM_FEATURE_POLL_CONTROL;
+        env->poll_control_msr = 1;
+    }
+
 out:
     if (local_err != NULL) {
         error_propagate(errp, local_err);

target/i386/kvm.c +0 -2

index cb22684139..81dd5d2c1b 100644
@@ -1796,8 +1796,6 @@ void kvm_arch_reset_vcpu(X86CPU *cpu)
 
         hyperv_x86_synic_reset(cpu);
     }
-    /* enabled by default */
-    env->poll_control_msr = 1;
 }
 
 void kvm_arch_do_init_vcpu(X86CPU *cpu)

target/i386/machine.c +0 -1

index 20077a8a5a..9d6095b264 100644
@@ -394,7 +394,6 @@ static bool steal_time_msr_needed(void *opaque)
     return cpu->env.steal_time_msr != 0;
 }
 
-/* Poll control MSR enabled by default */
 static bool poll_control_msr_needed(void *opaque)
 {
     X86CPU *cpu = opaque;

Signature · 1 line

2.21.0

Paolo Bonzini

maintainer

2019-07-16 21:09 UTC #3 lore raw

Quoted 5 lines · Mark Kanda

As such, I think we should only enable halt polling if it is supported on the host - see the attached patch.
...thoughts?

No, it should not be enabled by default at all, at least not until we can require kernel 5.2. My mistake, sorry. Can you post a patch?

Paolo

Paolo Bonzini

maintainer

2019-07-16 21:15 UTC #4 lore raw

Quoted 6 lines · Paolo Bonzini

Quoted 4 lines
As such, I think we should only enable halt polling if it is supported on the host - see the attached patch.
...thoughts?
No, it should not be enabled by default at all, at least not until we can require kernel 5.2. My mistake, sorry. Can you post a patch?

Doh, nevermind. This is not included in 4.1 so there's time to fix it.
Pfew. :)

Paolo

Mark Kanda

2019-07-16 21:21 UTC #5 lore raw

Quoted 11 lines · Paolo Bonzini

Quoted 6 lines · Paolo Bonzini
Quoted 4 lines
As such, I think we should only enable halt polling if it is supported on the host - see the attached patch.
...thoughts?
No, it should not be enabled by default at all, at least not until we can require kernel 5.2. My mistake, sorry. Can you post a patch?
Doh, nevermind. This is not included in 4.1 so there's time to fix it.
Pfew. :)

I'll post a patch regardless.

Thanks/regards,
-Mark