Re: [Qemu-devel] [PATCH RFC 1/1] arm64: add an option to turn on/off vpmu support

[Shannon Zhao <zhaoshenglong@huawei.com>]

On 2016/7/29 0:38, Wei Huang wrote:
> This patch adds a pmu=[on/off] option to enable/disable vpmu support
> in guest vm. There are several reasons to justify this option. First
> vpmu can be problematic for cross-migration between different SoC as
> perf counters is architecture-dependent. It is more flexible to
> have an option to turn it on/off. Secondly it matches the -cpu pmu
> option in libivrt. This patch has been tested on both DT/ACPI modes.
> 
> Signed-off-by: Wei Huang <wei@redhat.com>
Reviewed-by：Shannon Zhao <shannon.zhao@linaro.org>

> ---
>  hw/arm/virt-acpi-build.c |  2 +-
>  hw/arm/virt.c            |  2 +-
>  target-arm/cpu.c         |  1 +
>  target-arm/cpu.h         |  5 +++--
>  target-arm/kvm64.c       | 10 +++++-----
>  5 files changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index 28fc59c..dc5f66d 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 (armcpu->enable_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..6aea901 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 (!armcpu->enable_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..f7daf81 100644
> --- a/target-arm/cpu.c
> +++ b/target-arm/cpu.c
> @@ -1412,6 +1412,7 @@ static const ARMCPUInfo arm_cpus[] = {
>  };
>  
>  static Property arm_cpu_properties[] = {
> +    DEFINE_PROP_BOOL("pmu", ARMCPU, enable_pmu, true),
>      DEFINE_PROP_BOOL("start-powered-off", ARMCPU, start_powered_off, false),
>      DEFINE_PROP_UINT32("psci-conduit", ARMCPU, psci_conduit, 0),
>      DEFINE_PROP_UINT32("midr", ARMCPU, midr, 0),
> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
> index 76d824d..f2341c0 100644
> --- a/target-arm/cpu.h
> +++ b/target-arm/cpu.h
> @@ -579,8 +579,9 @@ struct ARMCPU {
>      bool powered_off;
>      /* CPU has security extension */
>      bool has_el3;
> -    /* CPU has PMU (Performance Monitor Unit) */
> -    bool has_pmu;
> +
> +    /* CPU has vPMU (Performance Monitor Unit) support */
> +    bool enable_pmu;
>  
>      /* CPU has memory protection unit */
>      bool has_mpu;
> diff --git a/target-arm/kvm64.c b/target-arm/kvm64.c
> index 5faa76c..ca21670 100644
> --- a/target-arm/kvm64.c
> +++ b/target-arm/kvm64.c
> @@ -501,11 +501,11 @@ 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;
> -        cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_PMU_V3;
> -    }
> +
> +    /* enable vPMU based on KVM mode and hardware capability */
> +    cpu->enable_pmu &= (kvm_irqchip_in_kernel() &&
> +        kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PMU_V3));
> +    cpu->kvm_init_features[0] |= cpu->enable_pmu << KVM_ARM_VCPU_PMU_V3;
>  
>      /* Do KVM_ARM_VCPU_INIT ioctl */
>      ret = kvm_arm_vcpu_init(cs);
> 

-- 
Shannon