[PATCH V2 02/11] target/i386: Don't save/restore PERF_GLOBAL_OVF_CTRL MSR

[Zide Chen <zide.chen@intel.com>]

From: Dapeng Mi <dapeng1.mi@linux.intel.com>

MSR_CORE_PERF_GLOBAL_OVF_CTRL is a write-only MSR and reads always
return zero.

Saving and restoring this MSR is therefore unnecessary.  Replace
VMSTATE_UINT64 with VMSTATE_UNUSED in the VMStateDescription to ignore
env.msr_global_ovf_ctrl during migration.  This avoids the need to bump
version_id and does not introduce any migration incompatibility.

Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
V2:
- No changes.

 target/i386/cpu.h     | 1 -
 target/i386/kvm/kvm.c | 6 ------
 target/i386/machine.c | 4 ++--
 3 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index f02812bfd19f..f6e9b274e2ff 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -2086,7 +2086,6 @@ typedef struct CPUArchState {
     uint64_t msr_fixed_ctr_ctrl;
     uint64_t msr_global_ctrl;
     uint64_t msr_global_status;
-    uint64_t msr_global_ovf_ctrl;
     uint64_t msr_fixed_counters[MAX_FIXED_COUNTERS];
     uint64_t msr_gp_counters[MAX_GP_COUNTERS];
     uint64_t msr_gp_evtsel[MAX_GP_COUNTERS];
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 7b9b740a8e5a..cffbc90d1c50 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -4069,8 +4069,6 @@ static int kvm_put_msrs(X86CPU *cpu, KvmPutState level)
             if (has_architectural_pmu_version > 1) {
                 kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_STATUS,
                                   env->msr_global_status);
-                kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_OVF_CTRL,
-                                  env->msr_global_ovf_ctrl);
 
                 /* Now start the PMU.  */
                 kvm_msr_entry_add(cpu, MSR_CORE_PERF_FIXED_CTR_CTRL,
@@ -4588,7 +4586,6 @@ static int kvm_get_msrs(X86CPU *cpu)
             kvm_msr_entry_add(cpu, MSR_CORE_PERF_FIXED_CTR_CTRL, 0);
             kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_CTRL, 0);
             kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_STATUS, 0);
-            kvm_msr_entry_add(cpu, MSR_CORE_PERF_GLOBAL_OVF_CTRL, 0);
         }
         for (i = 0; i < num_architectural_pmu_fixed_counters; i++) {
             kvm_msr_entry_add(cpu, MSR_CORE_PERF_FIXED_CTR0 + i, 0);
@@ -4917,9 +4914,6 @@ static int kvm_get_msrs(X86CPU *cpu)
         case MSR_CORE_PERF_GLOBAL_STATUS:
             env->msr_global_status = msrs[i].data;
             break;
-        case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
-            env->msr_global_ovf_ctrl = msrs[i].data;
-            break;
         case MSR_CORE_PERF_FIXED_CTR0 ... MSR_CORE_PERF_FIXED_CTR0 + MAX_FIXED_COUNTERS - 1:
             env->msr_fixed_counters[index - MSR_CORE_PERF_FIXED_CTR0] = msrs[i].data;
             break;
diff --git a/target/i386/machine.c b/target/i386/machine.c
index c9139612813b..1125c8a64ec5 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -666,7 +666,7 @@ static bool pmu_enable_needed(void *opaque)
     int i;
 
     if (env->msr_fixed_ctr_ctrl || env->msr_global_ctrl ||
-        env->msr_global_status || env->msr_global_ovf_ctrl) {
+        env->msr_global_status) {
         return true;
     }
     for (i = 0; i < MAX_FIXED_COUNTERS; i++) {
@@ -692,7 +692,7 @@ static const VMStateDescription vmstate_msr_architectural_pmu = {
         VMSTATE_UINT64(env.msr_fixed_ctr_ctrl, X86CPU),
         VMSTATE_UINT64(env.msr_global_ctrl, X86CPU),
         VMSTATE_UINT64(env.msr_global_status, X86CPU),
-        VMSTATE_UINT64(env.msr_global_ovf_ctrl, X86CPU),
+        VMSTATE_UNUSED(sizeof(uint64_t)),
         VMSTATE_UINT64_ARRAY(env.msr_fixed_counters, X86CPU, MAX_FIXED_COUNTERS),
         VMSTATE_UINT64_ARRAY(env.msr_gp_counters, X86CPU, MAX_GP_COUNTERS),
         VMSTATE_UINT64_ARRAY(env.msr_gp_evtsel, X86CPU, MAX_GP_COUNTERS),
-- 
2.52.0