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* [Qemu-devel] [PATCH] kvm: migrate vPMU state
@ 2013-07-24 14:37 Paolo Bonzini
  2013-07-24 15:01 ` Andreas Färber
  0 siblings, 1 reply; 6+ messages in thread
From: Paolo Bonzini @ 2013-07-24 14:37 UTC (permalink / raw)
  To: qemu-devel; +Cc: gnatapov, ehabkost

This requires kernel 3.10 but it is otherwise quite simple to do.
The kernel pays attention to MSRs writes that are host initiated, and
disables all side effects of the PMU registers (e.g. the global status
MSR can be written and global overflow control MSR does not clear bits
in the global status MSR).

Only two bits are interesting.  First, the number of general-purpose
counters must be fetched from CPUID so that we do not read non-existent
MSRs.  It need not be part of the migration stream.

Second, to avoid any possible side effects during the setting of MSRs
I stop the PMU while setting the counters and event selector MSRs.
Stopping the PMU snapshots the counters and ensures that no strange
races can happen if the counters were saved close to their overflow
value.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target-i386/cpu.h     | 23 +++++++++++++
 target-i386/kvm.c     | 93 ++++++++++++++++++++++++++++++++++++++++++++++++---
 target-i386/machine.c | 44 ++++++++++++++++++++++++
 3 files changed, 155 insertions(+), 5 deletions(-)

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index 058c57f..522eed4 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -304,6 +304,8 @@
 #define MSR_TSC_ADJUST                  0x0000003b
 #define MSR_IA32_TSCDEADLINE            0x6e0
 
+#define MSR_P6_PERFCTR0			0xc1
+
 #define MSR_MTRRcap			0xfe
 #define MSR_MTRRcap_VCNT		8
 #define MSR_MTRRcap_FIXRANGE_SUPPORT	(1 << 8)
@@ -317,6 +319,8 @@
 #define MSR_MCG_STATUS                  0x17a
 #define MSR_MCG_CTL                     0x17b
 
+#define MSR_P6_EVNTSEL0			0x186
+
 #define MSR_IA32_PERF_STATUS            0x198
 
 #define MSR_IA32_MISC_ENABLE		0x1a0
@@ -342,6 +346,14 @@
 
 #define MSR_MTRRdefType			0x2ff
 
+#define MSR_CORE_PERF_FIXED_CTR0	0x309
+#define MSR_CORE_PERF_FIXED_CTR1	0x30a
+#define MSR_CORE_PERF_FIXED_CTR2	0x30b
+#define MSR_CORE_PERF_FIXED_CTR_CTRL	0x38d
+#define MSR_CORE_PERF_GLOBAL_STATUS	0x38e
+#define MSR_CORE_PERF_GLOBAL_CTRL	0x38f
+#define MSR_CORE_PERF_GLOBAL_OVF_CTRL	0x390
+
 #define MSR_MC0_CTL			0x400
 #define MSR_MC0_STATUS			0x401
 #define MSR_MC0_ADDR			0x402
@@ -720,6 +732,9 @@ typedef struct {
 #define CPU_NB_REGS CPU_NB_REGS32
 #endif
 
+#define MAX_FIXED_COUNTERS 3
+#define MAX_GP_COUNTERS    (MSR_IA32_PERF_STATUS - MSR_P6_EVNTSEL0)
+
 #define NB_MMU_MODES 3
 
 typedef enum TPRAccess {
@@ -814,6 +829,14 @@ typedef struct CPUX86State {
     uint64_t mcg_status;
     uint64_t msr_ia32_misc_enable;
 
+    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];
+
     /* exception/interrupt handling */
     int error_code;
     int exception_is_int;
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 9ffb6ca..a209e8f 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -71,6 +71,9 @@ static bool has_msr_misc_enable;
 static bool has_msr_kvm_steal_time;
 static int lm_capable_kernel;
 
+static bool has_msr_architectural_pmu;
+static uint32_t num_architectural_pmu_counters;
+
 bool kvm_allows_irq0_override(void)
 {
     return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing();
@@ -579,6 +582,25 @@ int kvm_arch_init_vcpu(CPUState *cs)
             break;
         }
     }
+
+    if (limit >= 0x0a) {
+        uint32_t ver;
+
+        cpu_x86_cpuid(env, 0x0a, 0, &ver, &unused, &unused, &unused);
+        if ((ver & 0xff) > 0) {
+            has_msr_architectural_pmu = true;
+            num_architectural_pmu_counters = (ver & 0xff00) >> 8;
+
+            /* Shouldn't be more than 32, since that's the number of bits
+             * available in EBX to tell us _which_ counters are available.
+             * Play it safe.
+             */
+            if (num_architectural_pmu_counters > MAX_GP_COUNTERS) {
+                num_architectural_pmu_counters = MAX_GP_COUNTERS;
+            }
+        }
+    }
+
     cpu_x86_cpuid(env, 0x80000000, 0, &limit, &unused, &unused, &unused);
 
     for (i = 0x80000000; i <= limit; i++) {
@@ -1053,7 +1075,7 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
         struct kvm_msr_entry entries[100];
     } msr_data;
     struct kvm_msr_entry *msrs = msr_data.entries;
-    int n = 0;
+    int n = 0, i;
 
     kvm_msr_entry_set(&msrs[n++], MSR_IA32_SYSENTER_CS, env->sysenter_cs);
     kvm_msr_entry_set(&msrs[n++], MSR_IA32_SYSENTER_ESP, env->sysenter_esp);
@@ -1095,9 +1117,8 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
         }
     }
     /*
-     * The following paravirtual MSRs have side effects on the guest or are
-     * too heavy for normal writeback. Limit them to reset or full state
-     * updates.
+     * The following MSRs have side effects on the guest or are too heavy
+     * for normal writeback. Limit them to reset or full state updates.
      */
     if (level >= KVM_PUT_RESET_STATE) {
         kvm_msr_entry_set(&msrs[n++], MSR_KVM_SYSTEM_TIME,
@@ -1115,6 +1136,33 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
             kvm_msr_entry_set(&msrs[n++], MSR_KVM_STEAL_TIME,
                               env->steal_time_msr);
         }
+        if (has_msr_architectural_pmu) {
+            /* Stop the counter.  */
+            kvm_msr_entry_set(&msrs[n++], MSR_CORE_PERF_FIXED_CTR_CTRL, 0);
+            kvm_msr_entry_set(&msrs[n++], MSR_CORE_PERF_GLOBAL_CTRL, 0);
+
+            /* Set the counter values.  */
+            for (i = 0; i < MAX_FIXED_COUNTERS; i++) {
+                kvm_msr_entry_set(&msrs[n++], MSR_CORE_PERF_FIXED_CTR0 + i,
+                                  env->msr_fixed_counters[i]);
+            }
+            for (i = 0; i < num_architectural_pmu_counters; i++) {
+                kvm_msr_entry_set(&msrs[n++], MSR_P6_PERFCTR0 + i,
+                                  env->msr_gp_counters[i]);
+                kvm_msr_entry_set(&msrs[n++], MSR_P6_EVNTSEL0 + i,
+                                  env->msr_gp_evtsel[i]);
+            }
+            kvm_msr_entry_set(&msrs[n++], MSR_CORE_PERF_GLOBAL_STATUS,
+                              env->msr_global_status);
+            kvm_msr_entry_set(&msrs[n++], MSR_CORE_PERF_GLOBAL_OVF_CTRL,
+                              env->msr_global_ovf_ctrl);
+
+            /* Now start the PMU.  */
+            kvm_msr_entry_set(&msrs[n++], MSR_CORE_PERF_FIXED_CTR_CTRL,
+                              env->msr_fixed_ctr_ctrl);
+            kvm_msr_entry_set(&msrs[n++], MSR_CORE_PERF_GLOBAL_CTRL,
+                              env->msr_global_ctrl);
+        }
         if (hyperv_hypercall_available()) {
             kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_GUEST_OS_ID, 0);
             kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_HYPERCALL, 0);
@@ -1371,6 +1419,19 @@ static int kvm_get_msrs(X86CPU *cpu)
     if (has_msr_kvm_steal_time) {
         msrs[n++].index = MSR_KVM_STEAL_TIME;
     }
+    if (has_msr_architectural_pmu) {
+        msrs[n++].index = MSR_CORE_PERF_FIXED_CTR_CTRL;
+        msrs[n++].index = MSR_CORE_PERF_GLOBAL_CTRL;
+        msrs[n++].index = MSR_CORE_PERF_GLOBAL_STATUS;
+        msrs[n++].index = MSR_CORE_PERF_GLOBAL_OVF_CTRL;
+        for (i = 0; i < MAX_FIXED_COUNTERS; i++) {
+            msrs[n++].index = MSR_CORE_PERF_FIXED_CTR0 + i;
+        }
+        for (i = 0; i < num_architectural_pmu_counters; i++) {
+            msrs[n++].index = MSR_P6_PERFCTR0 + i;
+            msrs[n++].index = MSR_P6_EVNTSEL0 + i;
+        }
+    }
 
     if (env->mcg_cap) {
         msrs[n++].index = MSR_MCG_STATUS;
@@ -1387,7 +1448,8 @@ static int kvm_get_msrs(X86CPU *cpu)
     }
 
     for (i = 0; i < ret; i++) {
-        switch (msrs[i].index) {
+        uint32_t index = msrs[i].index;
+        switch (index) {
         case MSR_IA32_SYSENTER_CS:
             env->sysenter_cs = msrs[i].data;
             break;
@@ -1459,6 +1521,27 @@ static int kvm_get_msrs(X86CPU *cpu)
         case MSR_KVM_STEAL_TIME:
             env->steal_time_msr = msrs[i].data;
             break;
+        case MSR_CORE_PERF_FIXED_CTR_CTRL:
+            env->msr_fixed_ctr_ctrl = msrs[i].data;
+            break;
+        case MSR_CORE_PERF_GLOBAL_CTRL:
+            env->msr_global_ctrl = msrs[i].data;
+            break;
+        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;
+        case MSR_P6_PERFCTR0 ... MSR_P6_PERFCTR0 + MAX_GP_COUNTERS - 1:
+            env->msr_gp_counters[index - MSR_P6_PERFCTR0] = msrs[i].data;
+            break;
+        case MSR_P6_EVNTSEL0 ... MSR_P6_EVNTSEL0 + MAX_GP_COUNTERS - 1:
+            env->msr_gp_evtsel[index - MSR_P6_EVNTSEL0] = msrs[i].data;
+            break;
         }
     }
 
diff --git a/target-i386/machine.c b/target-i386/machine.c
index 3659db9..5bf9de6 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -410,6 +410,47 @@ static const VMStateDescription vmstate_msr_ia32_misc_enable = {
     }
 };
 
+static bool pmu_enable_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+    int i;
+
+    if (env->msr_fixed_ctr_ctrl || env->msr_global_ctrl ||
+        env->msr_global_status || env->msr_global_ovf_ctrl) {
+        return true;
+    }
+    for (i = 0; i < MAX_FIXED_COUNTERS; i++) {
+        if (env->msr_fixed_counters[i]) {
+            return true;
+        }
+    }
+    for (i = 0; i < MAX_GP_COUNTERS; i++) {
+        if (env->msr_gp_counters[i] || env->msr_gp_evtsel[i]) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+static const VMStateDescription vmstate_msr_architectural_pmu = {
+    .name = "cpu/msr_architectural_pmu",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField []) {
+        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_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),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 const VMStateDescription vmstate_x86_cpu = {
     .name = "cpu",
     .version_id = 12,
@@ -535,6 +576,9 @@ const VMStateDescription vmstate_x86_cpu = {
         }, {
             .vmsd = &vmstate_msr_ia32_misc_enable,
             .needed = misc_enable_needed,
+        }, {
+            .vmsd = &vmstate_msr_architectural_pmu,
+            .needed = pmu_enable_needed,
         } , {
             /* empty */
         }
-- 
1.8.3.1

^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-07-25 14:50 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-07-24 14:37 [Qemu-devel] [PATCH] kvm: migrate vPMU state Paolo Bonzini
2013-07-24 15:01 ` Andreas Färber
2013-07-25 10:14   ` Gleb Natapov
2013-07-25 10:27     ` Paolo Bonzini
2013-07-25 14:46     ` Andreas Färber
2013-07-25 14:50       ` Andreas Färber

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