[QEMU PATCH] kvm: support TSC deadline MSR with subsection

[Marcelo Tosatti <mtosatti@redhat.com>]

Jinsong, please test this qemu-kvm patch by migrating a guest which is
currently using TSC deadline timer. Using subsections avoids breaking
migration to older qemu versions when the guest does not make use of TSC
deadline feature.

-----

From: Liu, Jinsong <jinsong.liu@intel.com>

KVM add emulation of lapic tsc deadline timer for guest.
This patch is co-operation work at qemu side.

Use subsections to save/restore the field (mtosatti).

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index ae36489..29412dc 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -283,6 +283,7 @@
 #define MSR_IA32_APICBASE_BSP           (1<<8)
 #define MSR_IA32_APICBASE_ENABLE        (1<<11)
 #define MSR_IA32_APICBASE_BASE          (0xfffff<<12)
+#define MSR_IA32_TSCDEADLINE            0x6e0
 
 #define MSR_MTRRcap			0xfe
 #define MSR_MTRRcap_VCNT		8
@@ -687,6 +688,7 @@ typedef struct CPUX86State {
     uint64_t async_pf_en_msr;
 
     uint64_t tsc;
+    uint64_t tsc_deadline;
 
     uint64_t mcg_status;
 
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index b6eef04..90a6ffb 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -59,6 +59,7 @@ const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
 
 static bool has_msr_star;
 static bool has_msr_hsave_pa;
+static bool has_msr_tsc_deadline;
 static bool has_msr_async_pf_en;
 static int lm_capable_kernel;
 
@@ -568,6 +569,10 @@ static int kvm_get_supported_msrs(KVMState *s)
                     has_msr_hsave_pa = true;
                     continue;
                 }
+                if (kvm_msr_list->indices[i] == MSR_IA32_TSCDEADLINE) {
+                    has_msr_tsc_deadline = true;
+                    continue;
+                }
             }
         }
 
@@ -881,6 +886,9 @@ static int kvm_put_msrs(CPUState *env, int level)
     if (has_msr_hsave_pa) {
         kvm_msr_entry_set(&msrs[n++], MSR_VM_HSAVE_PA, env->vm_hsave);
     }
+    if (has_msr_tsc_deadline) {
+        kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSCDEADLINE, env->tsc_deadline);
+    }
 #ifdef TARGET_X86_64
     if (lm_capable_kernel) {
         kvm_msr_entry_set(&msrs[n++], MSR_CSTAR, env->cstar);
@@ -1127,6 +1135,9 @@ static int kvm_get_msrs(CPUState *env)
     if (has_msr_hsave_pa) {
         msrs[n++].index = MSR_VM_HSAVE_PA;
     }
+    if (has_msr_tsc_deadline) {
+        msrs[n++].index = MSR_IA32_TSCDEADLINE;
+    }
 
     if (!env->tsc_valid) {
         msrs[n++].index = MSR_IA32_TSC;
@@ -1195,6 +1206,9 @@ static int kvm_get_msrs(CPUState *env)
         case MSR_IA32_TSC:
             env->tsc = msrs[i].data;
             break;
+        case MSR_IA32_TSCDEADLINE:
+            env->tsc_deadline = msrs[i].data;
+            break;
         case MSR_VM_HSAVE_PA:
             env->vm_hsave = msrs[i].data;
             break;
diff --git a/target-i386/machine.c b/target-i386/machine.c
index 9aca8e0..176d372 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -310,6 +310,24 @@ static const VMStateDescription vmstate_fpop_ip_dp = {
     }
 };
 
+static bool tscdeadline_needed(void *opaque)
+{
+    CPUState *env = opaque;
+
+    return env->tsc_deadline != 0;
+}
+
+static const VMStateDescription vmstate_msr_tscdeadline = {
+    .name = "cpu/msr_tscdeadline",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField []) {
+        VMSTATE_UINT64(tsc_deadline, CPUState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription vmstate_cpu = {
     .name = "cpu",
     .version_id = CPU_SAVE_VERSION,
@@ -420,6 +438,9 @@ static const VMStateDescription vmstate_cpu = {
         } , {
             .vmsd = &vmstate_fpop_ip_dp,
             .needed = fpop_ip_dp_needed,
+        }, {
+            .vmsd = &vmstate_msr_tscdeadline,
+            .needed = tscdeadline_needed,
         } , {
             /* empty */
         }