Re: [Qemu-devel] [RFC PATCH V5 5/8] target-arm: Common kvm_arm_vcpu_init() for KVM ARM and KVM ARM64

[Peter Maydell]

On 12 May 2014 13:37, Pranavkumar Sawargaonkar <address@hidden> wrote:
> Introduce a common kvm_arm_vcpu_init() for doing KVM_ARM_VCPU_INIT
> ioctl in KVM ARM and KVM ARM64. This also helps us factor-out few
> common code lines from kvm_arch_init_vcpu() for KVM ARM/ARM64.

Mostly OK, some minor tweaks below.

> Signed-off-by: Pranavkumar Sawargaonkar <address@hidden>
> Signed-off-by: Anup Patel <address@hidden>
> ---
>  target-arm/cpu-qom.h |    3 +++
>  target-arm/kvm.c     |   16 ++++++++++++++++
>  target-arm/kvm32.c   |   18 ++++++++----------
>  target-arm/kvm64.c   |   24 ++++++++++++++----------
>  target-arm/kvm_arm.h |   13 +++++++++++++
>  5 files changed, 54 insertions(+), 20 deletions(-)
>
> diff --git a/target-arm/cpu-qom.h b/target-arm/cpu-qom.h
> index edc7f26..2bd7df8 100644
> --- a/target-arm/cpu-qom.h
> +++ b/target-arm/cpu-qom.h
> @@ -102,6 +102,9 @@ typedef struct ARMCPU {
>       */
>      uint32_t kvm_target;
>
> +    /* KVM init features for this CPU */
> +    uint32_t kvm_init_features[7];
> +
>      /* The instance init functions for implementation-specific subclasses
>       * set these fields to specify the implementation-dependent values of
>       * various constant registers and reset values of non-constant
> diff --git a/target-arm/kvm.c b/target-arm/kvm.c
> index 39202d7..74c90a7 100644
> --- a/target-arm/kvm.c
> +++ b/target-arm/kvm.c
> @@ -27,6 +27,22 @@ const KVMCapabilityInfo kvm_arch_required_capabilities[] = 
> {
>      KVM_CAP_LAST_INFO
>  };
>
> +int kvm_arm_vcpu_init(CPUState *cs)
> +{
> +    ARMCPU *cpu = ARM_CPU(cs);
> +    struct kvm_vcpu_init init;
> +
> +    if (cpu->kvm_target == QEMU_KVM_ARM_TARGET_NONE) {
> +        fprintf(stderr, "KVM is not supported for this guest CPU type\n");
> +        return -EINVAL;
> +    }

This check should stay in kvm_arch_init_vcpu(), not be moved to here.

> +
> +    init.target = cpu->kvm_target;
> +    memcpy(init.features, cpu->kvm_init_features, sizeof(init.features));
> +
> +    return kvm_vcpu_ioctl(cs, KVM_ARM_VCPU_INIT, &init);
> +}
> +
>  bool kvm_arm_create_scratch_host_vcpu(const uint32_t *cpus_to_try,
>                                        int *fdarray,
>                                        struct kvm_vcpu_init *init)
> diff --git a/target-arm/kvm32.c b/target-arm/kvm32.c
> index a690d99..cc9cdfa 100644
> --- a/target-arm/kvm32.c
> +++ b/target-arm/kvm32.c
> @@ -166,7 +166,6 @@ static int compare_u64(const void *a, const void *b)
>
>  int kvm_arch_init_vcpu(CPUState *cs)
>  {
> -    struct kvm_vcpu_init init;
>      int i, ret, arraylen;
>      uint64_t v;
>      struct kvm_one_reg r;
> @@ -174,20 +173,19 @@ int kvm_arch_init_vcpu(CPUState *cs)
>      struct kvm_reg_list *rlp;
>      ARMCPU *cpu = ARM_CPU(cs);
>
> -    if (cpu->kvm_target == QEMU_KVM_ARM_TARGET_NONE) {
> -        fprintf(stderr, "KVM is not supported for this guest CPU type\n");
> -        return -EINVAL;
> -    }
> -
> -    init.target = cpu->kvm_target;
> -    memset(init.features, 0, sizeof(init.features));
> +    /* Determine init features for this CPU */
> +    memset(cpu->kvm_init_features, 0, sizeof(cpu->kvm_init_features));
> +    cpu->kvm_init_features[0] = 0;

This = 0 line is just repeating work the memset() just did.

>      if (cpu->start_powered_off) {
> -        init.features[0] = 1 << KVM_ARM_VCPU_POWER_OFF;
> +        cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_POWER_OFF;
>      }
> -    ret = kvm_vcpu_ioctl(cs, KVM_ARM_VCPU_INIT, &init);
> +
> +    /* Do KVM_ARM_VCPU_INIT ioctl */
> +    ret = kvm_arm_vcpu_init(cs);
>      if (ret) {
>          return ret;
>      }
> +
>      /* Query the kernel to make sure it supports 32 VFP
>       * registers: QEMU's "cortex-a15" CPU is always a
>       * VFP-D32 core. The simplest way to do this is just
> diff --git a/target-arm/kvm64.c b/target-arm/kvm64.c
> index e115879..528536f 100644
> --- a/target-arm/kvm64.c
> +++ b/target-arm/kvm64.c
> @@ -77,26 +77,30 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUClass *ahcc)
>
>  int kvm_arch_init_vcpu(CPUState *cs)
>  {
> -    ARMCPU *cpu = ARM_CPU(cs);
> -    struct kvm_vcpu_init init;
>      int ret;
> +    ARMCPU *cpu = ARM_CPU(cs);
>
> -    if (cpu->kvm_target == QEMU_KVM_ARM_TARGET_NONE ||
> -        !arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
> -        fprintf(stderr, "KVM is not supported for this guest CPU type\n");
> +    if (!arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
> +        fprintf(stderr, "KVM only support Aarch64 CPU type\n");

Again, you don't need to change this guard/error.

>          return -EINVAL;
>      }
>
> -    init.target = cpu->kvm_target;
> -    memset(init.features, 0, sizeof(init.features));
> +    /* Determine init features for this CPU */
> +    memset(cpu->kvm_init_features, 0, sizeof(cpu->kvm_init_features));
> +    cpu->kvm_init_features[0] = 0;

Unnecessary.

>      if (cpu->start_powered_off) {
> -        init.features[0] = 1 << KVM_ARM_VCPU_POWER_OFF;
> +        cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_POWER_OFF;
> +    }
> +
> +    /* Do KVM_ARM_VCPU_INIT ioctl */
> +    ret = kvm_arm_vcpu_init(cs);
> +    if (ret) {
> +        return ret;
>      }
> -    ret = kvm_vcpu_ioctl(cs, KVM_ARM_VCPU_INIT, &init);
>
>      /* TODO : support for save/restore/reset of system regs via tuple list */
>
> -    return ret;
> +    return 0;
>  }
>
>  #define AARCH64_CORE_REG(x)   (KVM_REG_ARM64 | KVM_REG_SIZE_U64 | \
> diff --git a/target-arm/kvm_arm.h b/target-arm/kvm_arm.h
> index 137c567..31e845f 100644
> --- a/target-arm/kvm_arm.h
> +++ b/target-arm/kvm_arm.h
> @@ -15,6 +15,19 @@
>  #include "exec/memory.h"
>
>  /**
> + * kvm_arm_vcpu_init:
> + * @cs: CPUState
> + *
> + * KVM ARM and KVM ARM64 need to use KVM_ARM_VCPU_INIT ioctl for
> + * init/re-init/reset the VCPU with given feature flags.
> + * This is a common function for doing KVM_ARM_VCPU_INIT ioctl
> + * independent of KVM ARM or KVM ARM64.

I think it would be more informative if this read:
 * Initialize (or reinitialize) the VCPU by invoking the
 * KVM_ARM_VCPU_INIT ioctl with the CPU type and feature
 * bitmask specified in the CPUState.

> + *
> + * Returns: 0 if success else < 0 error code
> + */
> +int kvm_arm_vcpu_init(CPUState *cs);
> +
> +/**
>   * kvm_arm_register_device:
>   * @mr: memory region for this device
>   * @devid: the KVM device ID
> --
> 1.7.9.5
>

thanks
-- PMM