On Thu, Sep 17, 2020 at 11:20:23AM +0800, Ying Fang wrote: > 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/kvm64.c | 46 ++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 38 insertions(+), 8 deletions(-) > > diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c > index ef1e960285..fcce261a10 100644 > --- a/target/arm/kvm64.c > +++ b/target/arm/kvm64.c > @@ -757,10 +757,46 @@ static int kvm_arm_sve_set_vls(CPUState *cs) > > #define ARM_CPU_ID_MPIDR 3, 0, 0, 0, 5 > > +static int kvm_arm_set_mp_affinity(CPUState *cs) > +{ > + uint64_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;
We should query KVM first to determine if it wants guests to see their PEs as threads or not. If not, and ms->smp.threads is > 1, then that's an error. And, in any case, if ms->smp.threads == 1, then we shouldn't waste aff0 on it, as that could reduce IPI broadcast performance. > + 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 & ARM64_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, ARM64_SYS_REG(ARM_CPU_ID_MPIDR), > &mpidr); > + if (ret) { > + error_report("failed to set MPIDR"); We don't need this error, kvm_get_one_reg() has trace support already. Anyway, the wording is wrong since it says 'set' instead of 'get'. > + return ret; > + } > + cpu->mp_affinity = mpidr & ARM32_AFFINITY_MASK; > + return ret; > + } > +} > + > int kvm_arch_init_vcpu(CPUState *cs) > { > int ret; > - uint64_t mpidr; > ARMCPU *cpu = ARM_CPU(cs); > CPUARMState *env = &cpu->env; > > @@ -814,16 +850,10 @@ int kvm_arch_init_vcpu(CPUState *cs) > } > } > > - /* > - * 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); > + ret = kvm_arm_set_mp_affinity(cs); > if (ret) { > return ret; > } > - cpu->mp_affinity = mpidr & ARM64_AFFINITY_MASK; > > kvm_arm_init_debug(cs); > > -- > 2.23.0 > > Thanks, drew