[Qemu-devel] [PATCH v2 11/14] target/arm/kvm64: max cpu: Enable SVE when available

[Andrew Jones]

Enable SVE in the KVM guest when the 'max' cpu type is configured
and KVM supports it. KVM SVE requires use of the new finalize
vcpu ioctl, so we add that now too. For starters SVE can only be
turned on or off, getting all vector lengths the host CPU supports
when on. We'll add the other SVE CPU properties in later patches.

Signed-off-by: Andrew Jones <address@hidden>
---
 target/arm/cpu64.c       | 24 ++++++++++++++++++++++--
 target/arm/kvm.c         |  5 +++++
 target/arm/kvm64.c       | 25 ++++++++++++++++++++++++-
 target/arm/kvm_arm.h     | 27 +++++++++++++++++++++++++++
 tests/arm-cpu-features.c |  1 +
 5 files changed, 79 insertions(+), 3 deletions(-)

diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index 5def82111dee..2e595ad53137 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -371,6 +371,11 @@ void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp)
         return;
     }
 
+    /* sve-max-vq and sve<vl-bits> properties not yet implemented for KVM */
+    if (kvm_enabled()) {
+        return;
+    }
+
     if (cpu->sve_max_vq == ARM_SVE_INIT) {
         object_property_set_uint(OBJECT(cpu), ARM_MAX_VQ, "sve-max-vq", &err);
         if (err) {
@@ -632,6 +637,10 @@ static void cpu_arm_get_sve(Object *obj, Visitor *v, const 
char *name,
     ARMCPU *cpu = ARM_CPU(obj);
     bool value = !!cpu->sve_max_vq;
 
+    if (kvm_enabled() && !kvm_arm_sve_supported(CPU(cpu))) {
+        value = false;
+    }
+
     visit_type_bool(v, name, &value, errp);
 }
 
@@ -649,6 +658,11 @@ static void cpu_arm_set_sve(Object *obj, Visitor *v, const 
char *name,
     }
 
     if (value) {
+        if (kvm_enabled() && !kvm_arm_sve_supported(CPU(cpu))) {
+            error_setg(errp, "'sve' feature not supported by KVM on this 
host");
+            return;
+        }
+
         /*
          * We handle the -cpu <cpu>,sve=off,sve=on case by reinitializing,
          * but otherwise we don't do anything as an sve=on could come after
@@ -675,6 +689,11 @@ static void aarch64_max_initfn(Object *obj)
 
     if (kvm_enabled()) {
         kvm_arm_set_cpu_features_from_host(cpu);
+        /*
+         * KVM doesn't yet support the sve-max-vq property, but
+         * setting cpu->sve_max_vq is also used to turn SVE on.
+         */
+        cpu->sve_max_vq = ARM_SVE_INIT;
     } else {
         uint64_t t;
         uint32_t u;
@@ -764,8 +783,6 @@ static void aarch64_max_initfn(Object *obj)
         cpu->sve_max_vq = ARM_SVE_INIT;
         object_property_add(obj, "sve-max-vq", "uint32", 
cpu_max_get_sve_max_vq,
                             cpu_max_set_sve_max_vq, NULL, NULL, &error_fatal);
-        object_property_add(obj, "sve", "bool", cpu_arm_get_sve,
-                            cpu_arm_set_sve, NULL, NULL, &error_fatal);
 
         /*
          * sve_vq_map uses a special state while setting properties, so
@@ -780,6 +797,9 @@ static void aarch64_max_initfn(Object *obj)
                                 cpu_arm_set_sve_vq, NULL, NULL, &error_fatal);
         }
     }
+
+    object_property_add(obj, "sve", "bool", cpu_arm_get_sve,
+                        cpu_arm_set_sve, NULL, NULL, &error_fatal);
 }
 
 struct ARMCPUInfo {
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 69c961a4c62c..60645a196d3d 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -49,6 +49,11 @@ int kvm_arm_vcpu_init(CPUState *cs)
     return kvm_vcpu_ioctl(cs, KVM_ARM_VCPU_INIT, &init);
 }
 
+int kvm_arm_vcpu_finalize(CPUState *cs, int feature)
+{
+    return kvm_vcpu_ioctl(cs, KVM_ARM_VCPU_FINALIZE, &feature);
+}
+
 void kvm_arm_init_serror_injection(CPUState *cs)
 {
     cap_has_inject_serror_esr = kvm_check_extension(cs->kvm_state,
diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index 706541327491..9fc7f078cf68 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -604,6 +604,15 @@ bool kvm_arm_aarch32_supported(CPUState *cpu)
     return ret > 0;
 }
 
+bool kvm_arm_sve_supported(CPUState *cpu)
+{
+    KVMState *s = KVM_STATE(current_machine->accelerator);
+    int ret;
+
+    ret = kvm_check_extension(s, KVM_CAP_ARM_SVE);
+    return ret > 0;
+}
+
 #define ARM_CPU_ID_MPIDR       3, 0, 0, 0, 5
 
 int kvm_arch_init_vcpu(CPUState *cs)
@@ -632,13 +641,20 @@ int kvm_arch_init_vcpu(CPUState *cs)
         cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_EL1_32BIT;
     }
     if (!kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PMU_V3)) {
-            cpu->has_pmu = false;
+        cpu->has_pmu = false;
     }
     if (cpu->has_pmu) {
         cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_PMU_V3;
     } else {
         unset_feature(&env->features, ARM_FEATURE_PMU);
     }
+    if (cpu->sve_max_vq) {
+        if (!kvm_arm_sve_supported(cs)) {
+            cpu->sve_max_vq = 0;
+        } else {
+            cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_SVE;
+        }
+    }
 
     /* Do KVM_ARM_VCPU_INIT ioctl */
     ret = kvm_arm_vcpu_init(cs);
@@ -646,6 +662,13 @@ int kvm_arch_init_vcpu(CPUState *cs)
         return ret;
     }
 
+    if (cpu->sve_max_vq) {
+        ret = kvm_arm_vcpu_finalize(cs, KVM_ARM_VCPU_SVE);
+        if (ret) {
+            return ret;
+        }
+    }
+
     /*
      * When KVM is in use, PSCI is emulated in-kernel and not by qemu.
      * Currently KVM has its own idea about MPIDR assignment, so we
diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index e0ded3607996..2367f8ab78ed 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -27,6 +27,20 @@
  */
 int kvm_arm_vcpu_init(CPUState *cs);
 
+/**
+ * kvm_arm_vcpu_finalize
+ * @cs: CPUState
+ * @feature: int
+ *
+ * Finalizes the configuration of the specified VCPU feature by
+ * invoking the KVM_ARM_VCPU_FINALIZE ioctl. Features requiring
+ * this are documented in the "KVM_ARM_VCPU_FINALIZE" section of
+ * KVM's API documentation.
+ *
+ * Returns: 0 if success else < 0 error code
+ */
+int kvm_arm_vcpu_finalize(CPUState *cs, int feature);
+
 /**
  * kvm_arm_register_device:
  * @mr: memory region for this device
@@ -224,6 +238,14 @@ bool kvm_arm_aarch32_supported(CPUState *cs);
  */
 bool kvm_arm_pmu_supported(CPUState *cs);
 
+/**
+ * bool kvm_arm_sve_supported:
+ * @cs: CPUState
+ *
+ * Returns true if the KVM VCPU can enable SVE and false otherwise.
+ */
+bool kvm_arm_sve_supported(CPUState *cs);
+
 /**
  * kvm_arm_get_max_vm_ipa_size - Returns the number of bits in the
  * IPA address space supported by KVM
@@ -274,6 +296,11 @@ static inline bool kvm_arm_pmu_supported(CPUState *cs)
     return false;
 }
 
+static inline bool kvm_arm_sve_supported(CPUState *cs)
+{
+    return false;
+}
+
 static inline int kvm_arm_get_max_vm_ipa_size(MachineState *ms)
 {
     return -ENOENT;
diff --git a/tests/arm-cpu-features.c b/tests/arm-cpu-features.c
index a4bf6aec00df..67ad5f2b78d5 100644
--- a/tests/arm-cpu-features.c
+++ b/tests/arm-cpu-features.c
@@ -393,6 +393,7 @@ static void test_query_cpu_model_expansion_kvm(const void 
*data)
 
     if (g_str_equal(qtest_get_arch(), "aarch64")) {
         assert_has_feature(qts, "host", "aarch64");
+        assert_has_feature(qts, "max", "sve");
 
         assert_error(qts, "cortex-a15",
             "The CPU definition 'cortex-a15' cannot "
-- 
2.20.1