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 <drjo...@redhat.com> --- 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