[PATCH v2 03/12] target/arm/cpu: spe: Add an option to turn on/off vSPE support

[Haibo Xu <haibo.xu@linaro.org>]

Adds a spe=[on/off] option to enable/disable vSPE support in
guest vCPU.

Signed-off-by: Haibo Xu <haibo.xu@linaro.org>
---
 target/arm/cpu.c   |  6 ++++++
 target/arm/cpu.h   | 13 ++++++++++++
 target/arm/cpu64.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+)

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index c179e0752d..f211958eaa 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1310,6 +1310,12 @@ void arm_cpu_finalize_features(ARMCPU *cpu, Error **errp)
             error_propagate(errp, local_err);
             return;
         }
+
+        arm_cpu_spe_finalize(cpu, &local_err);
+        if (local_err != NULL) {
+            error_propagate(errp, local_err);
+            return;
+        }
     }
 }
 
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index a1c7d8ebae..baf2bbcee8 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)
@@ -196,9 +197,11 @@ typedef struct {
 #ifdef TARGET_AARCH64
 # define ARM_MAX_VQ    16
 void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp);
+void arm_cpu_spe_finalize(ARMCPU *cpu, Error **errp);
 #else
 # define ARM_MAX_VQ    1
 static inline void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp) { }
+static inline void arm_cpu_spe_finalize(ARMCPU *cpu, Error **errp) { }
 #endif
 
 typedef struct ARMVectorReg {
@@ -829,6 +832,8 @@ struct ARMCPU {
     bool has_el3;
     /* CPU has PMU (Performance Monitor Unit) */
     bool has_pmu;
+    /* CPU has SPE (Statistical Profiling Extension) */
+    OnOffAuto has_spe;
     /* CPU has VFP */
     bool has_vfp;
     /* CPU has Neon */
@@ -3869,6 +3874,14 @@ static inline bool isar_feature_aa64_pmu_8_4(const ARMISARegisters *id)
         FIELD_EX64(id->id_aa64dfr0, ID_AA64DFR0, PMUVER) != 0xf;
 }
 
+/*
+ * Currently we don't differentiate between the ARMv8.2-SPE and ARMv8.3-SPE.
+ */
+static inline bool isar_feature_aa64_spe(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->id_aa64dfr0, ID_AA64DFR0, PMSVER) != 0;
+}
+
 static inline bool isar_feature_aa64_rcpc_8_3(const ARMISARegisters *id)
 {
     return FIELD_EX64(id->id_aa64isar1, ID_AA64ISAR1, LRCPC) != 0;
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index 3c2b3d9599..4997c4a3c0 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -572,6 +572,55 @@ void aarch64_add_sve_properties(Object *obj)
     }
 }
 
+void arm_cpu_spe_finalize(ARMCPU *cpu, Error **errp)
+{
+    uint64_t t;
+    uint32_t value = 0;
+
+    if (cpu->has_spe == ON_OFF_AUTO_AUTO) {
+        if (kvm_enabled() && kvm_arm_spe_supported()) {
+            cpu->has_spe = ON_OFF_AUTO_ON;
+        } else {
+            cpu->has_spe = ON_OFF_AUTO_OFF;
+        }
+    } else if (cpu->has_spe == ON_OFF_AUTO_ON) {
+        if (!kvm_enabled() || !kvm_arm_spe_supported()) {
+            error_setg(errp, "'spe' cannot be enabled on this host");
+            return;
+        }
+    }
+
+    /*
+     * According to the ARM ARM, the ID_AA64DFR0[PMSVER] currently
+     * support 3 values:
+     *
+     * 0b0000: SPE not implemented
+     * 0b0001: ARMv8.2-SPE implemented
+     * 0b0010: ARMv8.3-SPE implemented
+     *
+     * But the kernel KVM API didn't expose all these 3 values, and
+     * we can only get whether the SPE feature is supported or not.
+     * So here we just set the PMSVER to 1 if this feature was supported.
+     */
+    if (cpu->has_spe == ON_OFF_AUTO_ON) {
+        value = 1;
+    }
+
+    t = cpu->isar.id_aa64dfr0;
+    t = FIELD_DP64(t, ID_AA64DFR0, PMSVER, value);
+    cpu->isar.id_aa64dfr0 = t;
+}
+
+static bool arm_spe_get(Object *obj, Error **errp)
+{
+    return ARM_CPU(obj)->has_spe != ON_OFF_AUTO_OFF;
+}
+
+static void arm_spe_set(Object *obj, bool value, Error **errp)
+{
+    ARM_CPU(obj)->has_spe = value ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;
+}
+
 /* -cpu max: if KVM is enabled, like -cpu host (best possible with this host);
  * otherwise, a CPU with as many features enabled as our emulation supports.
  * The version of '-cpu max' for qemu-system-arm is defined in cpu.c;
@@ -721,6 +770,9 @@ static void aarch64_max_initfn(Object *obj)
     aarch64_add_sve_properties(obj);
     object_property_add(obj, "sve-max-vq", "uint32", cpu_max_get_sve_max_vq,
                         cpu_max_set_sve_max_vq, NULL, NULL);
+
+    cpu->has_spe = ON_OFF_AUTO_AUTO;
+    object_property_add_bool(obj, "spe", arm_spe_get, arm_spe_set);
 }
 
 static const ARMCPUInfo aarch64_cpus[] = {
-- 
2.17.1