[PATCH] KVM: x86: Add support for save/load MSR_SMI_COUNT

[Liran Alon <liran.alon@xxxxxxxxxx>]

This MSR returns the number of #SMIs that occurred on
CPU since boot.

KVM commit 52797bf9a875 ("KVM: x86: Add emulation of MSR_SMI_COUNT")
introduced support for emulating this MSR.

This commit adds support for QEMU to save/load this
MSR for migration purposes.

Signed-off-by: Liran Alon <liran.alon@xxxxxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 target/i386/cpu.c     |  1 +
 target/i386/cpu.h     |  3 +++
 target/i386/kvm.c     | 13 +++++++++++++
 target/i386/machine.c | 20 ++++++++++++++++++++
 4 files changed, 37 insertions(+)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index b5e431e769da..ba9ec6a6116b 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -3645,6 +3645,7 @@ static void x86_cpu_reset(CPUState *s)
     cpu_x86_update_cr0(env, 0x60000010);
     env->a20_mask = ~0x0;
     env->smbase = 0x30000;
+    env->msr_smi_count = 0;
 
     env->idt.limit = 0xffff;
     env->gdt.limit = 0xffff;
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index faf39ec1ce77..254e557bb8fa 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1,3 +1,4 @@
+
 /*
  * i386 virtual CPU header
  *
@@ -359,6 +360,7 @@ typedef enum X86Seg {
 #define MSR_P6_PERFCTR0                 0xc1
 
 #define MSR_IA32_SMBASE                 0x9e
+#define MSR_SMI_COUNT                   0x34
 #define MSR_MTRRcap                     0xfe
 #define MSR_MTRRcap_VCNT                8
 #define MSR_MTRRcap_FIXRANGE_SUPPORT    (1 << 8)
@@ -1123,6 +1125,7 @@ typedef struct CPUX86State {
 
     uint64_t pat;
     uint32_t smbase;
+    uint64_t msr_smi_count;
 
     uint32_t pkru;
 
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index ad4b159b28af..a53735f266c5 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -92,6 +92,7 @@ static bool has_msr_hv_stimer;
 static bool has_msr_hv_frequencies;
 static bool has_msr_xss;
 static bool has_msr_spec_ctrl;
+static bool has_msr_smi_count;
 
 static uint32_t has_architectural_pmu_version;
 static uint32_t num_architectural_pmu_gp_counters;
@@ -1124,6 +1125,9 @@ static int kvm_get_supported_msrs(KVMState *s)
                 case MSR_IA32_SMBASE:
                     has_msr_smbase = true;
                     break;
+                case MSR_SMI_COUNT:
+                    has_msr_smi_count = true;
+                    break;
                 case MSR_IA32_MISC_ENABLE:
                     has_msr_misc_enable = true;
                     break;
@@ -1633,6 +1637,9 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
     if (has_msr_smbase) {
         kvm_msr_entry_add(cpu, MSR_IA32_SMBASE, env->smbase);
     }
+    if (has_msr_smi_count) {
+        kvm_msr_entry_add(cpu, MSR_SMI_COUNT, env->msr_smi_count);
+    }
     if (has_msr_bndcfgs) {
         kvm_msr_entry_add(cpu, MSR_IA32_BNDCFGS, env->msr_bndcfgs);
     }
@@ -1979,6 +1986,9 @@ static int kvm_get_msrs(X86CPU *cpu)
     if (has_msr_smbase) {
         kvm_msr_entry_add(cpu, MSR_IA32_SMBASE, 0);
     }
+    if (has_msr_smi_count) {
+        kvm_msr_entry_add(cpu, MSR_SMI_COUNT, 0);
+    }
     if (has_msr_feature_control) {
         kvm_msr_entry_add(cpu, MSR_IA32_FEATURE_CONTROL, 0);
     }
@@ -2205,6 +2215,9 @@ static int kvm_get_msrs(X86CPU *cpu)
         case MSR_IA32_SMBASE:
             env->smbase = msrs[i].data;
             break;
+        case MSR_SMI_COUNT:
+            env->msr_smi_count = msrs[i].data;
+            break;
         case MSR_IA32_FEATURE_CONTROL:
             env->msr_ia32_feature_control = msrs[i].data;
             break;
diff --git a/target/i386/machine.c b/target/i386/machine.c
index 361c05aedfdc..9432496cbda8 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -395,6 +395,25 @@ static const VMStateDescription vmstate_msr_tsc_adjust = {
     }
 };
 
+static bool msr_smi_count_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->msr_smi_count != 0;
+}
+
+static const VMStateDescription vmstate_msr_smi_count = {
+    .name = "cpu/msr_smi_count",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = msr_smi_count_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(env.msr_smi_count, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static bool tscdeadline_needed(void *opaque)
 {
     X86CPU *cpu = opaque;
@@ -952,6 +971,7 @@ VMStateDescription vmstate_x86_cpu = {
         &vmstate_avx512,
         &vmstate_xss,
         &vmstate_tsc_khz,
+        &vmstate_msr_smi_count,
 #ifdef TARGET_X86_64
         &vmstate_pkru,
 #endif
-- 
1.9.1