[Qemu-devel] [PATCH 2/2] arm: kvm: set MPIDR when we can

[Andrew Jones <drjones@redhat.com>]

If KVM supports user provided MPIDRs for the vcpus, then provide
them. This simplifies management of vcpus as we can be sure of
the identity of a vcpu even before it's been instantiated.

Cc: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 target/arm/cpu.c   |  3 +--
 target/arm/kvm32.c | 22 ++++++++++++++--------
 target/arm/kvm64.c | 22 ++++++++++++++--------
 3 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index f7157dc0e59d..83cd5eefbef8 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -741,8 +741,7 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
         return;
     }
 
-    /* This cpu-id-to-MPIDR affinity is used only for TCG; KVM will override it.
-     * We don't support setting cluster ID ([16..23]) (known as Aff2
+    /* We don't currently support setting cluster ID ([16..23]) (known as Aff2
      * in later ARM ARM versions), or any of the higher affinity level fields,
      * so these bits always RAZ.
      */
diff --git a/target/arm/kvm32.c b/target/arm/kvm32.c
index 069da0c5fd10..5ad732498e5c 100644
--- a/target/arm/kvm32.c
+++ b/target/arm/kvm32.c
@@ -186,7 +186,6 @@ int kvm_arch_init_vcpu(CPUState *cs)
 {
     int ret;
     uint64_t v;
-    uint32_t mpidr;
     struct kvm_one_reg r;
     ARMCPU *cpu = ARM_CPU(cs);
 
@@ -223,16 +222,23 @@ int kvm_arch_init_vcpu(CPUState *cs)
         return -EINVAL;
     }
 
-    /*
-     * 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
-     * override our defaults with what we get from KVM.
-     */
-    ret = kvm_get_one_reg(cs, ARM_CP15_REG32(ARM_CPU_ID_MPIDR), &mpidr);
+    if (kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_USER_MPIDR)) {
+        ret = kvm_set_one_reg(cs, ARM_CP15_REG32(ARM_CPU_ID_MPIDR),
+                              &cpu->mp_affinity);
+    } else {
+        /* If we can't set the MPIDR, then KVM will generate one. We must
+         * update our copy to that one in order to stay synchronized.
+         */
+        uint32_t mpidr;
+
+        ret = kvm_get_one_reg(cs, ARM_CP15_REG32(ARM_CPU_ID_MPIDR), &mpidr);
+        if (!ret) {
+            cpu->mp_affinity = mpidr & ARM32_AFFINITY_MASK;
+        }
+    }
     if (ret) {
         return ret;
     }
-    cpu->mp_affinity = mpidr & ARM32_AFFINITY_MASK;
 
     return kvm_arm_init_cpreg_list(cpu);
 }
diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index 61111091ad3b..a7d3f876c43b 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -486,7 +486,6 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUClass *ahcc)
 int kvm_arch_init_vcpu(CPUState *cs)
 {
     int ret;
-    uint64_t mpidr;
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;
 
@@ -524,16 +523,23 @@ int kvm_arch_init_vcpu(CPUState *cs)
         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
-     * override our defaults with what we get from KVM.
-     */
-    ret = kvm_get_one_reg(cs, ARM64_SYS_REG(ARM_CPU_ID_MPIDR), &mpidr);
+    if (kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_USER_MPIDR)) {
+        ret = kvm_set_one_reg(cs, ARM64_SYS_REG(ARM_CPU_ID_MPIDR),
+                              &cpu->mp_affinity);
+    } else {
+        /* If we can't set the MPIDR, then KVM will generate one. We must
+         * update our copy to that one in order to stay synchronized.
+         */
+        uint64_t mpidr;
+
+        ret = kvm_get_one_reg(cs, ARM64_SYS_REG(ARM_CPU_ID_MPIDR), &mpidr);
+        if (!ret) {
+            cpu->mp_affinity = mpidr & ARM64_AFFINITY_MASK;
+        }
+    }
     if (ret) {
         return ret;
     }
-    cpu->mp_affinity = mpidr & ARM64_AFFINITY_MASK;
 
     kvm_arm_init_debug(cs);
 
-- 
2.9.3