hw/arm/virt: Implement kvm-steal-time

We add the kvm-steal-time CPU property and implement it for machvirt.
A tiny bit of refactoring was also done to allow pmu and pvtime to
use the same vcpu device helper functions.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
Message-id: 20201001061718.101915-7-drjones@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

6 files changed, 131 insertions, 6 deletions

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 858c5a4bcb..056319859f 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1310,6 +1310,14 @@ void arm_cpu_finalize_features(ARMCPU *cpu, Error **errp)
             return;
         }
     }
+
+    if (kvm_enabled()) {
+        kvm_arm_steal_time_finalize(cpu, &local_err);
+        if (local_err != NULL) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    }
 }
 
 static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index e4549a8cc0..cfff1b5c8f 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -24,6 +24,7 @@
 #include "hw/registerfields.h"
 #include "cpu-qom.h"
 #include "exec/cpu-defs.h"
+#include "qapi/qapi-types-common.h"
 
 /* ARM processors have a weak memory model */
 #define TCG_GUEST_DEFAULT_MO      (0)
@@ -863,6 +864,9 @@ struct ARMCPU {
     bool kvm_vtime_dirty;
     uint64_t kvm_vtime;
 
+    /* KVM steal time */
+    OnOffAuto kvm_steal_time;
+
     /* Uniprocessor system with MP extensions */
     bool mp_is_up;
 
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 0dcb9bfe13..ffe186de8d 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -192,6 +192,16 @@ static void kvm_no_adjvtime_set(Object *obj, bool value, Error **errp)
     ARM_CPU(obj)->kvm_adjvtime = !value;
 }
 
+static bool kvm_steal_time_get(Object *obj, Error **errp)
+{
+    return ARM_CPU(obj)->kvm_steal_time != ON_OFF_AUTO_OFF;
+}
+
+static void kvm_steal_time_set(Object *obj, bool value, Error **errp)
+{
+    ARM_CPU(obj)->kvm_steal_time = value ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;
+}
+
 /* KVM VCPU properties should be prefixed with "kvm-". */
 void kvm_arm_add_vcpu_properties(Object *obj)
 {
@@ -207,6 +217,12 @@ void kvm_arm_add_vcpu_properties(Object *obj)
                                         "the virtual counter. VM stopped time "
                                         "will be counted.");
     }
+
+    cpu->kvm_steal_time = ON_OFF_AUTO_AUTO;
+    object_property_add_bool(obj, "kvm-steal-time", kvm_steal_time_get,
+                             kvm_steal_time_set);
+    object_property_set_description(obj, "kvm-steal-time",
+                                    "Set off to disable KVM steal time.");
 }
 
 bool kvm_arm_pmu_supported(void)
diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index fae07c3f04..f74bac2457 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -17,6 +17,7 @@
 #include <linux/kvm.h>
 
 #include "qemu-common.h"
+#include "qapi/error.h"
 #include "cpu.h"
 #include "qemu/timer.h"
 #include "qemu/error-report.h"
@@ -397,19 +398,20 @@ static CPUWatchpoint *find_hw_watchpoint(CPUState *cpu, target_ulong addr)
     return NULL;
 }
 
-static bool kvm_arm_pmu_set_attr(CPUState *cs, struct kvm_device_attr *attr)
+static bool kvm_arm_set_device_attr(CPUState *cs, struct kvm_device_attr *attr,
+                                    const char *name)
 {
     int err;
 
     err = kvm_vcpu_ioctl(cs, KVM_HAS_DEVICE_ATTR, attr);
     if (err != 0) {
-        error_report("PMU: KVM_HAS_DEVICE_ATTR: %s", strerror(-err));
+        error_report("%s: KVM_HAS_DEVICE_ATTR: %s", name, strerror(-err));
         return false;
     }
 
     err = kvm_vcpu_ioctl(cs, KVM_SET_DEVICE_ATTR, attr);
     if (err != 0) {
-        error_report("PMU: KVM_SET_DEVICE_ATTR: %s", strerror(-err));
+        error_report("%s: KVM_SET_DEVICE_ATTR: %s", name, strerror(-err));
         return false;
     }
 
@@ -426,7 +428,7 @@ void kvm_arm_pmu_init(CPUState *cs)
     if (!ARM_CPU(cs)->has_pmu) {
         return;
     }
-    if (!kvm_arm_pmu_set_attr(cs, &attr)) {
+    if (!kvm_arm_set_device_attr(cs, &attr, "PMU")) {
         error_report("failed to init PMU");
         abort();
     }
@@ -443,12 +445,29 @@ void kvm_arm_pmu_set_irq(CPUState *cs, int irq)
     if (!ARM_CPU(cs)->has_pmu) {
         return;
     }
-    if (!kvm_arm_pmu_set_attr(cs, &attr)) {
+    if (!kvm_arm_set_device_attr(cs, &attr, "PMU")) {
         error_report("failed to set irq for PMU");
         abort();
     }
 }
 
+void kvm_arm_pvtime_init(CPUState *cs, uint64_t ipa)
+{
+    struct kvm_device_attr attr = {
+        .group = KVM_ARM_VCPU_PVTIME_CTRL,
+        .attr = KVM_ARM_VCPU_PVTIME_IPA,
+        .addr = (uint64_t)&ipa,
+    };
+
+    if (ARM_CPU(cs)->kvm_steal_time == ON_OFF_AUTO_OFF) {
+        return;
+    }
+    if (!kvm_arm_set_device_attr(cs, &attr, "PVTIME IPA")) {
+        error_report("failed to init PVTIME IPA");
+        abort();
+    }
+}
+
 static int read_sys_reg32(int fd, uint32_t *pret, uint64_t id)
 {
     uint64_t ret;
@@ -655,6 +674,36 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
     return true;
 }
 
+void kvm_arm_steal_time_finalize(ARMCPU *cpu, Error **errp)
+{
+    bool has_steal_time = kvm_arm_steal_time_supported();
+
+    if (cpu->kvm_steal_time == ON_OFF_AUTO_AUTO) {
+        if (!has_steal_time || !arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
+            cpu->kvm_steal_time = ON_OFF_AUTO_OFF;
+        } else {
+            cpu->kvm_steal_time = ON_OFF_AUTO_ON;
+        }
+    } else if (cpu->kvm_steal_time == ON_OFF_AUTO_ON) {
+        if (!has_steal_time) {
+            error_setg(errp, "'kvm-steal-time' cannot be enabled "
+                             "on this host");
+            return;
+        } else if (!arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
+            /*
+             * DEN0057A chapter 2 says "This specification only covers
+             * systems in which the Execution state of the hypervisor
+             * as well as EL1 of virtual machines is AArch64.". And,
+             * to ensure that, the smc/hvc calls are only specified as
+             * smc64/hvc64.
+             */
+            error_setg(errp, "'kvm-steal-time' cannot be enabled "
+                             "for AArch32 guests");
+            return;
+        }
+    }
+}
+
 bool kvm_arm_aarch32_supported(void)
 {
     return kvm_check_extension(kvm_state, KVM_CAP_ARM_EL1_32BIT);
@@ -665,6 +714,11 @@ bool kvm_arm_sve_supported(void)
     return kvm_check_extension(kvm_state, KVM_CAP_ARM_SVE);
 }
 
+bool kvm_arm_steal_time_supported(void)
+{
+    return kvm_check_extension(kvm_state, KVM_CAP_STEAL_TIME);
+}
+
 QEMU_BUILD_BUG_ON(KVM_ARM64_SVE_VQ_MIN != 1);
 
 void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map)
diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index f513702176..eb81b7059e 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -268,6 +268,24 @@ void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu);
 void kvm_arm_add_vcpu_properties(Object *obj);
 
 /**
+ * kvm_arm_steal_time_finalize:
+ * @cpu: ARMCPU for which to finalize kvm-steal-time
+ * @errp: Pointer to Error* for error propagation
+ *
+ * Validate the kvm-steal-time property selection and set its default
+ * based on KVM support and guest configuration.
+ */
+void kvm_arm_steal_time_finalize(ARMCPU *cpu, Error **errp);
+
+/**
+ * kvm_arm_steal_time_supported:
+ *
+ * Returns: true if KVM can enable steal time reporting
+ * and false otherwise.
+ */
+bool kvm_arm_steal_time_supported(void);
+
+/**
  * kvm_arm_aarch32_supported:
  *
  * Returns: true if KVM can enable AArch32 mode
@@ -340,6 +358,16 @@ int kvm_arm_vgic_probe(void);
 
 void kvm_arm_pmu_set_irq(CPUState *cs, int irq);
 void kvm_arm_pmu_init(CPUState *cs);
+
+/**
+ * kvm_arm_pvtime_init:
+ * @cs: CPUState
+ * @ipa: Per-vcpu guest physical base address of the pvtime structures
+ *
+ * Initializes PVTIME for the VCPU, setting the PVTIME IPA to @ipa.
+ */
+void kvm_arm_pvtime_init(CPUState *cs, uint64_t ipa);
+
 int kvm_arm_set_irq(int cpu, int irqtype, int irq, int level);
 
 #else
@@ -363,6 +391,11 @@ static inline bool kvm_arm_sve_supported(void)
     return false;
 }
 
+static inline bool kvm_arm_steal_time_supported(void)
+{
+    return false;
+}
+
 /*
  * These functions should never actually be called without KVM support.
  */
@@ -396,6 +429,16 @@ static inline void kvm_arm_pmu_init(CPUState *cs)
     g_assert_not_reached();
 }
 
+static inline void kvm_arm_pvtime_init(CPUState *cs, uint64_t ipa)
+{
+    g_assert_not_reached();
+}
+
+static inline void kvm_arm_steal_time_finalize(ARMCPU *cpu, Error **errp)
+{
+    g_assert_not_reached();
+}
+
 static inline void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map)
 {
     g_assert_not_reached();
diff --git a/target/arm/monitor.c b/target/arm/monitor.c
index 375f34bfaa..169d8a64b6 100644
--- a/target/arm/monitor.c
+++ b/target/arm/monitor.c
@@ -103,7 +103,7 @@ static const char *cpu_model_advertised_features[] = {
     "sve128", "sve256", "sve384", "sve512",
     "sve640", "sve768", "sve896", "sve1024", "sve1152", "sve1280",
     "sve1408", "sve1536", "sve1664", "sve1792", "sve1920", "sve2048",
-    "kvm-no-adjvtime",
+    "kvm-no-adjvtime", "kvm-steal-time",
     NULL
 };