[RFC PATCH 03/12] target/arm/kvm32: make MPIDR consistent with CPU Topology

[Ying Fang]

MPIDR helps to provide an additional PE identification in a multiprocessor
system. This patch adds support for setting MPIDR from userspace, so that
MPIDR is consistent with CPU topology configured.

Signed-off-by: Ying Fang <fangyi...@huawei.com>
---
 target/arm/kvm32.c | 46 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 38 insertions(+), 8 deletions(-)

diff --git a/target/arm/kvm32.c b/target/arm/kvm32.c
index 0af46b41c8..85694dc8bf 100644
--- a/target/arm/kvm32.c
+++ b/target/arm/kvm32.c
@@ -201,11 +201,47 @@ int kvm_arm_cpreg_level(uint64_t regidx)
 
 #define ARM_CPU_ID_MPIDR       0, 0, 0, 5
 
+static int kvm_arm_set_mp_affinity(CPUState *cs)
+{
+    uint32_t mpidr;
+    ARMCPU *cpu = ARM_CPU(cs);
+
+    if (kvm_check_extension(kvm_state, KVM_CAP_ARM_MP_AFFINITY)) {
+        /* Make MPIDR consistent with CPU topology */
+        MachineState *ms = MACHINE(qdev_get_machine());
+
+        mpidr = (kvm_arch_vcpu_id(cs) % ms->smp.threads) << ARM_AFF0_SHIFT;
+        mpidr |= ((kvm_arch_vcpu_id(cs) / ms->smp.threads % ms->smp.cores)
+                                        & 0xff) << ARM_AFF1_SHIFT;
+        mpidr |= (kvm_arch_vcpu_id(cs) / (ms->smp.cores * ms->smp.threads)
+                                       & 0xff) << ARM_AFF2_SHIFT;
+
+        /* Override mp affinity when KVM is in use */
+        cpu->mp_affinity = mpidr & ARM32_AFFINITY_MASK;
+
+        /* Bit 31 is RES1 indicates the ARMv7 Multiprocessing Extensions */
+        mpidr |= (1ULL << 31);
+        return kvm_vcpu_ioctl(cs, KVM_ARM_SET_MP_AFFINITY, &mpidr);
+    } else {
+        /*
+         * When KVM_CAP_ARM_MP_AFFINITY is not supported, it means KVM has its
+         * own idea about MPIDR assignment, so we override our defaults with
+         * what we get from KVM.
+         */
+        int ret = kvm_get_one_reg(cs, ARM_CP15_REG32(ARM_CPU_ID_MPIDR), 
&mpidr);
+        if (ret) {
+            error_report("failed to set MPIDR");
+            return ret;
+        }
+        cpu->mp_affinity = mpidr & ARM32_AFFINITY_MASK;
+        return ret;
+    }
+}
+
 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);
 
@@ -244,16 +280,10 @@ 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);
+    ret = kvm_arm_set_mp_affinity(cs);
     if (ret) {
         return ret;
     }
-    cpu->mp_affinity = mpidr & ARM32_AFFINITY_MASK;
 
     /* Check whether userspace can specify guest syndrome value */
     kvm_arm_init_serror_injection(cs);
-- 
2.23.0