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[RFC PATCH 5/5] target/arm/cpu: Add the kvm-adjvtime CPU property
From: |
Andrew Jones |
Subject: |
[RFC PATCH 5/5] target/arm/cpu: Add the kvm-adjvtime CPU property |
Date: |
Mon, 7 Oct 2019 19:06:22 +0200 |
kvm-adjvtime is a KVM specific CPU property and a first of its kind.
To accommodate it we also add kvm_arm_add_vcpu_properties() and a
KVM specific CPU properties description to the CPU features document.
Signed-off-by: Andrew Jones <address@hidden>
---
docs/arm-cpu-features.rst | 27 ++++++++++++++++++++++++++-
target/arm/cpu.c | 2 ++
target/arm/cpu64.c | 1 +
target/arm/kvm.c | 27 +++++++++++++++++++++++++++
target/arm/kvm_arm.h | 11 +++++++++++
target/arm/monitor.c | 1 +
tests/arm-cpu-features.c | 4 ++++
7 files changed, 72 insertions(+), 1 deletion(-)
diff --git a/docs/arm-cpu-features.rst b/docs/arm-cpu-features.rst
index 1b367e22e16e..5c317296845f 100644
--- a/docs/arm-cpu-features.rst
+++ b/docs/arm-cpu-features.rst
@@ -31,7 +31,9 @@ supporting the feature or only supporting the feature under
certain
configurations. For example, the `aarch64` CPU feature, which, when
disabled, enables the optional AArch32 CPU feature, is only supported
when using the KVM accelerator and when running on a host CPU type that
-supports the feature.
+supports the feature. While `aarch64` currently only works with KVM,
+it could work with TCG. CPU features that are specific to KVM are
+prefixed with "kvm-" and are described in "KVM VCPU Features".
CPU Feature Probing
===================
@@ -171,6 +173,29 @@ disabling many SVE vector lengths would be quite verbose,
the `sve<N>` CPU
properties have special semantics (see "SVE CPU Property Parsing
Semantics").
+KVM VCPU Features
+=================
+
+KVM VCPU features are CPU features that are specific to KVM, such as
+paravirt features or features that enable CPU virtualization extensions.
+The features' CPU properties are only available when KVM is enabled and are
+named with the prefix "kvm-". KVM VCPU features may be probed, enabled, and
+disabled in the same way as other CPU features. Below is the list of KVM
+VCPU features and their descriptions.
+
+ kvm-adjvtime When enabled, each time the VM transitions back
+ to running state the VCPU's vitual counter is
+ updated to ensure stopped time is not counted.
+ This avoids time jumps surprising guest OSes and
+ applications, as long as they use the virtual
+ counter for timekeeping, but has the side effect
+ of the virtual and physical counters diverging.
+ All timekeeping based on the virtual counter will
+ appear to lag behind any timekeeping that does
+ not subtract VM stopped time. The guest may
+ resynchronize its virtual counter with other time
+ sources as needed.
+
SVE CPU Properties
==================
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 7695ae551218..d8ad26438f9f 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -2483,6 +2483,7 @@ static void arm_max_initfn(Object *obj)
if (kvm_enabled()) {
kvm_arm_set_cpu_features_from_host(cpu);
+ kvm_arm_add_vcpu_properties(obj);
} else {
cortex_a15_initfn(obj);
@@ -2674,6 +2675,7 @@ static void arm_host_initfn(Object *obj)
if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
aarch64_add_sve_properties(obj);
}
+ kvm_arm_add_vcpu_properties(obj);
arm_cpu_post_init(obj);
}
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index 68baf0482ffa..c9a657a178ce 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -620,6 +620,7 @@ static void aarch64_max_initfn(Object *obj)
if (kvm_enabled()) {
kvm_arm_set_cpu_features_from_host(cpu);
+ kvm_arm_add_vcpu_properties(obj);
} else {
uint64_t t;
uint32_t u;
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index f79b9b8ef57a..1652e3febe51 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -17,6 +17,8 @@
#include "qemu/timer.h"
#include "qemu/error-report.h"
#include "qemu/main-loop.h"
+#include "qom/object.h"
+#include "qapi/error.h"
#include "sysemu/sysemu.h"
#include "sysemu/kvm.h"
#include "sysemu/kvm_int.h"
@@ -179,6 +181,31 @@ void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
env->features = arm_host_cpu_features.features;
}
+static bool kvm_adjvtime_get(Object *obj, Error **errp)
+{
+ return ARM_CPU(obj)->kvm_adjvtime;
+}
+
+static void kvm_adjvtime_set(Object *obj, bool value, Error **errp)
+{
+ ARM_CPU(obj)->kvm_adjvtime = value;
+}
+
+/* KVM VCPU properties should be prefixed with "kvm-". */
+void kvm_arm_add_vcpu_properties(Object *obj)
+{
+ if (!kvm_enabled()) {
+ return;
+ }
+
+ object_property_add_bool(obj, "kvm-adjvtime", kvm_adjvtime_get,
+ kvm_adjvtime_set, &error_abort);
+ object_property_set_description(obj, "kvm-adjvtime",
+ "Set on to enable the adjustment of "
+ "the virtual counter. VM stopped time "
+ "will not be counted.", &error_abort);
+}
+
bool kvm_arm_pmu_supported(CPUState *cpu)
{
KVMState *s = KVM_STATE(current_machine->accelerator);
diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index d506c4e84be6..5d8077df6a4a 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -232,6 +232,15 @@ void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map);
*/
void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu);
+/**
+ * void kvm_arm_add_vcpu_properties:
+ * @obj: The CPU object to add the properties to
+ *
+ * Add all KVM specific CPU properties to the CPU object. These
+ * are the CPU properties with "kvm-" prefixed names.
+ */
+void kvm_arm_add_vcpu_properties(Object *obj);
+
/**
* void kvm_arm_set_virtual_time:
* @cs: CPUState
@@ -308,6 +317,8 @@ static inline void
kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
cpu->host_cpu_probe_failed = true;
}
+static inline void kvm_arm_add_vcpu_properties(Object *obj) {}
+
static inline bool kvm_arm_aarch32_supported(CPUState *cs)
{
return false;
diff --git a/target/arm/monitor.c b/target/arm/monitor.c
index e912ed2cefa0..a89976fe7e4b 100644
--- a/target/arm/monitor.c
+++ b/target/arm/monitor.c
@@ -103,6 +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-adjvtime",
NULL
};
diff --git a/tests/arm-cpu-features.c b/tests/arm-cpu-features.c
index ee444b04010f..c207a2bec9e9 100644
--- a/tests/arm-cpu-features.c
+++ b/tests/arm-cpu-features.c
@@ -417,6 +417,8 @@ static void test_query_cpu_model_expansion(const void *data)
assert_has_feature_enabled(qts, "cortex-a15", "pmu");
assert_has_not_feature(qts, "cortex-a15", "aarch64");
+ assert_has_not_feature(qts, "max", "kvm-adjvtime");
+
if (g_str_equal(qtest_get_arch(), "aarch64")) {
assert_has_feature_enabled(qts, "max", "aarch64");
assert_has_feature_enabled(qts, "max", "sve");
@@ -445,6 +447,8 @@ static void test_query_cpu_model_expansion_kvm(const void
*data)
assert_has_feature_enabled(qts, "host", "pmu");
+ assert_has_feature_disabled(qts, "host", "kvm-adjvtime");
+
if (g_str_equal(qtest_get_arch(), "aarch64")) {
bool kvm_supports_sve;
char max_name[8], name[8];
--
2.20.1