target-i386: Enabling IA32_TSC_ADJUST for QEMU KVM guest VMs

CPUID.7.0.EBX[1]=1 indicates IA32_TSC_ADJUST MSR 0x3b is supported

Basic design is to emulate the MSR by allowing reads and writes to the
hypervisor vcpu specific locations to store the value of the emulated MSRs.
In this way the IA32_TSC_ADJUST value will be included in all reads to
the TSC MSR whether through rdmsr or rdtsc.

As this is a new MSR that the guest may access and modify its value needs
to be migrated along with the other MRSs. The changes here are specifically
for recognizing when IA32_TSC_ADJUST is enabled in CPUID and code added
for migrating its value.

Signed-off-by: Will Auld <will.auld@intel.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index 386c4f6d98882203283d31d2932f314b56b31a1a..477da33aa82e38e94e05012a9ecb55d14795440c 100644 (file)
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -295,6 +295,7 @@
 #define MSR_IA32_APICBASE_BSP           (1<<8)
 #define MSR_IA32_APICBASE_ENABLE        (1<<11)
 #define MSR_IA32_APICBASE_BASE          (0xfffff<<12)
+#define MSR_TSC_ADJUST                  0x0000003b
 #define MSR_IA32_TSCDEADLINE            0x6e0
 
 #define MSR_MTRRcap                    0xfe
@@ -774,6 +775,7 @@ typedef struct CPUX86State {
     uint64_t pv_eoi_en_msr;
 
     uint64_t tsc;
+    uint64_t tsc_adjust;
     uint64_t tsc_deadline;
 
     uint64_t mcg_status;

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index f669281e13c9e4c29930c62a401b8ab42945fa14..ae6ce1ff3cb6672d54faeea60941e28f58509939 100644 (file)
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -62,6 +62,7 @@ const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
 
 static bool has_msr_star;
 static bool has_msr_hsave_pa;
+static bool has_msr_tsc_adjust;
 static bool has_msr_tsc_deadline;
 static bool has_msr_async_pf_en;
 static bool has_msr_pv_eoi_en;
@@ -676,6 +677,10 @@ static int kvm_get_supported_msrs(KVMState *s)
                     has_msr_hsave_pa = true;
                     continue;
                 }
+                if (kvm_msr_list->indices[i] == MSR_TSC_ADJUST) {
+                    has_msr_tsc_adjust = true;
+                    continue;
+                }
                 if (kvm_msr_list->indices[i] == MSR_IA32_TSCDEADLINE) {
                     has_msr_tsc_deadline = true;
                     continue;
@@ -1013,6 +1018,9 @@ static int kvm_put_msrs(CPUX86State *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_adjust) {
+        kvm_msr_entry_set(&msrs[n++], MSR_TSC_ADJUST, env->tsc_adjust);
+    }
     if (has_msr_tsc_deadline) {
         kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSCDEADLINE, env->tsc_deadline);
     }
@@ -1273,6 +1281,9 @@ static int kvm_get_msrs(CPUX86State *env)
     if (has_msr_hsave_pa) {
         msrs[n++].index = MSR_VM_HSAVE_PA;
     }
+    if (has_msr_tsc_adjust) {
+        msrs[n++].index = MSR_TSC_ADJUST;
+    }
     if (has_msr_tsc_deadline) {
         msrs[n++].index = MSR_IA32_TSCDEADLINE;
     }
@@ -1350,6 +1361,9 @@ static int kvm_get_msrs(CPUX86State *env)
         case MSR_IA32_TSC:
             env->tsc = msrs[i].data;
             break;
+        case MSR_TSC_ADJUST:
+            env->tsc_adjust = msrs[i].data;
+            break;
         case MSR_IA32_TSCDEADLINE:
             env->tsc_deadline = msrs[i].data;
             break;

diff --git a/target-i386/machine.c b/target-i386/machine.c
index 477150887bb4fe8248bbd0c6dbb9c25208110d4a..4229ddeac89bdfc520d9909d1872666c4ec5684d 100644 (file)
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -328,6 +328,24 @@ static const VMStateDescription vmstate_fpop_ip_dp = {
     }
 };
 
+static bool tsc_adjust_needed(void *opaque)
+{
+    CPUX86State *env = opaque;
+
+    return env->tsc_adjust != 0;
+}
+
+static const VMStateDescription vmstate_msr_tsc_adjust = {
+    .name = "cpu/msr_tsc_adjust",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField[]) {
+        VMSTATE_UINT64(tsc_adjust, CPUX86State),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static bool tscdeadline_needed(void *opaque)
 {
     CPUX86State *env = opaque;
@@ -477,6 +495,9 @@ static const VMStateDescription vmstate_cpu = {
         } , {
             .vmsd = &vmstate_fpop_ip_dp,
             .needed = fpop_ip_dp_needed,
+        }, {
+            .vmsd = &vmstate_msr_tsc_adjust,
+            .needed = tsc_adjust_needed,
         }, {
             .vmsd = &vmstate_msr_tscdeadline,
             .needed = tscdeadline_needed,