Re: [Qemu-devel] [PATCH V4 1/2] arm64: Add an option to turn on/off vPMU support

[Wei Huang]

On 09/21/2016 02:53 AM, Andrew Jones wrote:
> On Tue, Sep 20, 2016 at 10:33:53PM -0400, Wei Huang wrote:
>> This patch adds a pmu=[on/off] option to enable/disable vPMU support
>> in guest vCPU. This option is only available for cortex-a57/cortex-53/
>> host under both TCG and KVM modes, but unavailable on ARMv7 and other
>> processors. It allows virt tools, such as libvirt, to determine the
>> exsitence of vPMU and configure it. Note that, if nothing specified,
>> the pmu option is set to AUTO as default, allowing machine-level PMU
>> property to override it. Also when pmu is turned on under non-KVM mode,
>> a warning message will be printed.
>>
>> Signed-off-by: Wei Huang <address@hidden>
>> ---
>>  hw/arm/virt-acpi-build.c |  2 +-
>>  hw/arm/virt.c            |  2 +-
>>  target-arm/cpu.c         | 23 +++++++++++++++++++++++
>>  target-arm/cpu.h         |  5 +++--
>>  target-arm/cpu64.c       |  2 ++
>>  target-arm/kvm64.c       | 17 ++++++++++++++---
>>  6 files changed, 44 insertions(+), 7 deletions(-)
>>
>> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
>> index 295ec86..8b3083e 100644
>> --- a/hw/arm/virt-acpi-build.c
>> +++ b/hw/arm/virt-acpi-build.c
>> @@ -540,7 +540,7 @@ build_madt(GArray *table_data, BIOSLinker *linker, 
>> VirtGuestInfo *guest_info)
>>          gicc->uid = i;
>>          gicc->flags = cpu_to_le32(ACPI_GICC_ENABLED);
>>  
>> -        if (armcpu->has_pmu) {
>> +        if (arm_feature(&armcpu->env, ARM_FEATURE_PMU)) {
>>              gicc->performance_interrupt = cpu_to_le32(PPI(VIRTUAL_PMU_IRQ));
>>          }
>>      }
>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>> index a193b5a..a781ad0 100644
>> --- a/hw/arm/virt.c
>> +++ b/hw/arm/virt.c
>> @@ -477,7 +477,7 @@ static void fdt_add_pmu_nodes(const VirtBoardInfo *vbi, 
>> int gictype)
>>  
>>      CPU_FOREACH(cpu) {
>>          armcpu = ARM_CPU(cpu);
>> -        if (!armcpu->has_pmu ||
>> +        if (!arm_feature(&armcpu->env, ARM_FEATURE_PMU) ||
>>              !kvm_arm_pmu_create(cpu, PPI(VIRTUAL_PMU_IRQ))) {
>>              return;
>>          }
>> diff --git a/target-arm/cpu.c b/target-arm/cpu.c
>> index ce8b8f4..ed7b884 100644
>> --- a/target-arm/cpu.c
>> +++ b/target-arm/cpu.c
>> @@ -19,6 +19,7 @@
>>   */
>>  
>>  #include "qemu/osdep.h"
>> +#include "qemu/error-report.h"
>>  #include "qapi/error.h"
>>  #include "cpu.h"
>>  #include "internals.h"
>> @@ -31,6 +32,7 @@
>>  #include "hw/arm/arm.h"
>>  #include "sysemu/sysemu.h"
>>  #include "sysemu/kvm.h"
>> +#include "sysemu/qtest.h"
>>  #include "kvm_arm.h"
>>  
>>  static void arm_cpu_set_pc(CPUState *cs, vaddr value)
>> @@ -509,6 +511,10 @@ static Property arm_cpu_rvbar_property =
>>  static Property arm_cpu_has_el3_property =
>>              DEFINE_PROP_BOOL("has_el3", ARMCPU, has_el3, true);
>>  
>> +/* use property name "pmu" to match other archs and virt tools */
>> +static Property arm_cpu_has_pmu_property =
>> +    DEFINE_PROP_ON_OFF_AUTO("pmu", ARMCPU, has_pmu, ON_OFF_AUTO_AUTO);
>> +
>>  static Property arm_cpu_has_mpu_property =
>>              DEFINE_PROP_BOOL("has-mpu", ARMCPU, has_mpu, true);
>>  
>> @@ -552,6 +558,11 @@ static void arm_cpu_post_init(Object *obj)
>>  #endif
>>      }
>>  
>> +    if (arm_feature(&cpu->env, ARM_FEATURE_PMU)) {
>> +        qdev_property_add_static(DEVICE(obj), &arm_cpu_has_pmu_property,
>> +                                 &error_abort);
>> +    }
>> +
>>      if (arm_feature(&cpu->env, ARM_FEATURE_MPU)) {
>>          qdev_property_add_static(DEVICE(obj), &arm_cpu_has_mpu_property,
>>                                   &error_abort);
>> @@ -576,6 +587,7 @@ static void arm_cpu_realizefn(DeviceState *dev, Error 
>> **errp)
>>      ARMCPU *cpu = ARM_CPU(dev);
>>      ARMCPUClass *acc = ARM_CPU_GET_CLASS(dev);
>>      CPUARMState *env = &cpu->env;
>> +    static bool pmu_warned;
>>  
>>      /* Some features automatically imply others: */
>>      if (arm_feature(env, ARM_FEATURE_V8)) {
>> @@ -648,6 +660,17 @@ static void arm_cpu_realizefn(DeviceState *dev, Error 
>> **errp)
>>          cpu->id_aa64pfr0 &= ~0xf000;
>>      }
>>  
>> +    if (cpu->has_pmu == ON_OFF_AUTO_ON && !kvm_enabled()) {
>> +        cpu->has_pmu = ON_OFF_AUTO_OFF;
>> +        if (!pmu_warned && !qtest_enabled()) {
> 
> Why do we need this qtest_enabled thing?

Without this, "make check" will print out the warning message (using a
qtest machine type). This seems to be a common practice across QEMU code.

> 
>> +            error_report("warning: pmu can't be enabled without KVM 
>> acceleration");
>> +            pmu_warned = true;
>> +        }
>> +    }
>> +    if (cpu->has_pmu == ON_OFF_AUTO_OFF) {
>> +        unset_feature(env, ARM_FEATURE_PMU);
>> +    }
>> +
>>      if (!arm_feature(env, ARM_FEATURE_EL2)) {
>>          /* Disable the hypervisor feature bits in the processor feature
>>           * registers if we don't have EL2. These are id_pfr1[15:12] and
>> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
>> index 76d824d..c8625eb 100644
>> --- a/target-arm/cpu.h
>> +++ b/target-arm/cpu.h
>> @@ -579,8 +579,8 @@ struct ARMCPU {
>>      bool powered_off;
>>      /* CPU has security extension */
>>      bool has_el3;
>> -    /* CPU has PMU (Performance Monitor Unit) */
>> -    bool has_pmu;
>> +    /* CPU PMU (Performance Monitor Unit) config, tri-state */
> 
> The comment didn't need to be modified.
> 
>> +    OnOffAuto has_pmu;
>>  
>>      /* CPU has memory protection unit */
>>      bool has_mpu;
>> @@ -1129,6 +1129,7 @@ enum arm_features {
>>      ARM_FEATURE_V8_SHA256, /* implements SHA256 part of v8 Crypto 
>> Extensions */
>>      ARM_FEATURE_V8_PMULL, /* implements PMULL part of v8 Crypto Extensions 
>> */
>>      ARM_FEATURE_THUMB_DSP, /* DSP insns supported in the Thumb encodings */
>> +    ARM_FEATURE_PMU, /* has PMU support */
>>  };
>>  
>>  static inline int arm_feature(CPUARMState *env, int feature)
>> diff --git a/target-arm/cpu64.c b/target-arm/cpu64.c
>> index 1635deb..549cb1e 100644
>> --- a/target-arm/cpu64.c
>> +++ b/target-arm/cpu64.c
>> @@ -111,6 +111,7 @@ static void aarch64_a57_initfn(Object *obj)
>>      set_feature(&cpu->env, ARM_FEATURE_V8_PMULL);
>>      set_feature(&cpu->env, ARM_FEATURE_CRC);
>>      set_feature(&cpu->env, ARM_FEATURE_EL3);
>> +    set_feature(&cpu->env, ARM_FEATURE_PMU);
>>      cpu->kvm_target = QEMU_KVM_ARM_TARGET_CORTEX_A57;
>>      cpu->midr = 0x411fd070;
>>      cpu->revidr = 0x00000000;
>> @@ -166,6 +167,7 @@ static void aarch64_a53_initfn(Object *obj)
>>      set_feature(&cpu->env, ARM_FEATURE_V8_PMULL);
>>      set_feature(&cpu->env, ARM_FEATURE_CRC);
>>      set_feature(&cpu->env, ARM_FEATURE_EL3);
>> +    set_feature(&cpu->env, ARM_FEATURE_PMU);
>>      cpu->kvm_target = QEMU_KVM_ARM_TARGET_CORTEX_A53;
>>      cpu->midr = 0x410fd034;
>>      cpu->revidr = 0x00000000;
>> diff --git a/target-arm/kvm64.c b/target-arm/kvm64.c
>> index 5faa76c..ff86550 100644
>> --- a/target-arm/kvm64.c
>> +++ b/target-arm/kvm64.c
>> @@ -428,6 +428,11 @@ static inline void set_feature(uint64_t *features, int 
>> feature)
>>      *features |= 1ULL << feature;
>>  }
>>  
>> +static inline void unset_feature(uint64_t *features, int feature)
>> +{
>> +    *features &= ~(1ULL << feature);
>> +}
>> +
>>  bool kvm_arm_get_host_cpu_features(ARMHostCPUClass *ahcc)
>>  {
>>      /* Identify the feature bits corresponding to the host CPU, and
>> @@ -469,6 +474,7 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUClass *ahcc)
>>      set_feature(&features, ARM_FEATURE_VFP4);
>>      set_feature(&features, ARM_FEATURE_NEON);
>>      set_feature(&features, ARM_FEATURE_AARCH64);
>> +    set_feature(&features, ARM_FEATURE_PMU);
>>  
>>      ahcc->features = features;
>>  
>> @@ -482,6 +488,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
>>      int ret;
>>      uint64_t mpidr;
>>      ARMCPU *cpu = ARM_CPU(cs);
>> +    CPUARMState *env = &cpu->env;
>>  
>>      if (cpu->kvm_target == QEMU_KVM_ARM_TARGET_NONE ||
>>          !object_dynamic_cast(OBJECT(cpu), TYPE_AARCH64_CPU)) {
>> @@ -501,10 +508,14 @@ int kvm_arch_init_vcpu(CPUState *cs)
>>      if (!arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
>>          cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_EL1_32BIT;
>>      }
>> -    if (kvm_irqchip_in_kernel() &&
>> -        kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PMU_V3)) {
>> -        cpu->has_pmu = true;
>> +    if (!kvm_irqchip_in_kernel() ||
>> +        !kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PMU_V3)) {
>> +            cpu->has_pmu = ON_OFF_AUTO_OFF;
>> +    }
>> +    if (cpu->has_pmu == ON_OFF_AUTO_ON) {
>>          cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_PMU_V3;
>> +    } else {
>> +        unset_feature(&env->features, ARM_FEATURE_PMU);
>>      }
>>  
>>      /* Do KVM_ARM_VCPU_INIT ioctl */
>> -- 
>> 1.8.3.1
>>
>>