Hi Anup,

thanks for the re-spin and sorry for the delay.

Looks better now, some minor comments below.

On 19/09/14 00:57, Anup Patel wrote:
> Instead, of trying out each and every target type we should
> use KVM_ARM_PREFERRED_TARGET vm ioctl to determine target type
> for KVM ARM/ARM64.
> 
> If KVM_ARM_PREFERRED_TARGET vm ioctl fails then we fallback to
> old method of trying all known target types.
> 
> If KVM_ARM_PREFERRED_TARGET vm ioctl succeeds but the returned
> target type is not known to KVMTOOL then we forcefully init
> VCPU with target type returned by KVM_ARM_PREFERRED_TARGET vm ioctl.
> 
> Signed-off-by: Pranavkumar Sawargaonkar <pranavku...@linaro.org>
> Signed-off-by: Anup Patel <anup.pa...@linaro.org>
> ---
>  tools/kvm/arm/aarch32/arm-cpu.c |    9 ++++++-
>  tools/kvm/arm/aarch64/arm-cpu.c |   10 ++++++--
>  tools/kvm/arm/kvm-cpu.c         |   52 
> ++++++++++++++++++++++++++++++---------
>  3 files changed, 57 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/kvm/arm/aarch32/arm-cpu.c b/tools/kvm/arm/aarch32/arm-cpu.c
> index 71b98fe..0d2ff11 100644
> --- a/tools/kvm/arm/aarch32/arm-cpu.c
> +++ b/tools/kvm/arm/aarch32/arm-cpu.c
> @@ -22,6 +22,12 @@ static int arm_cpu__vcpu_init(struct kvm_cpu *vcpu)
>       return 0;
>  }
>  
> +static struct kvm_arm_target target_generic_v7 = {
> +     .id             = UINT_MAX,
> +     .compatible     = "arm,arm-v7",
> +     .init           = arm_cpu__vcpu_init,
> +};
> +
>  static struct kvm_arm_target target_cortex_a15 = {
>       .id             = KVM_ARM_TARGET_CORTEX_A15,
>       .compatible     = "arm,cortex-a15",
> @@ -36,7 +42,8 @@ static struct kvm_arm_target target_cortex_a7 = {
>  
>  static int arm_cpu__core_init(struct kvm *kvm)
>  {
> -     return (kvm_cpu__register_kvm_arm_target(&target_cortex_a15) ||
> +     return (kvm_cpu__register_kvm_arm_target(&target_generic_v7) ||
> +             kvm_cpu__register_kvm_arm_target(&target_cortex_a15) ||
>               kvm_cpu__register_kvm_arm_target(&target_cortex_a7));
>  }

I wonder if you could avoid the registration of this target and instead
reference it later directly (instead of using a magic 0 index)?
This way you wouldn't need to care about avoiding accidental .id matches
with the UINT_MAX above.

>  core_init(arm_cpu__core_init);
> diff --git a/tools/kvm/arm/aarch64/arm-cpu.c b/tools/kvm/arm/aarch64/arm-cpu.c
> index ce5ea2f..9ee3da3 100644
> --- a/tools/kvm/arm/aarch64/arm-cpu.c
> +++ b/tools/kvm/arm/aarch64/arm-cpu.c
> @@ -16,13 +16,18 @@ static void generate_fdt_nodes(void *fdt, struct kvm 
> *kvm, u32 gic_phandle)
>       timer__generate_fdt_nodes(fdt, kvm, timer_interrupts);
>  }
>  
> -
>  static int arm_cpu__vcpu_init(struct kvm_cpu *vcpu)
>  {
>       vcpu->generate_fdt_nodes = generate_fdt_nodes;
>       return 0;
>  }
>  
> +static struct kvm_arm_target target_generic_v8 = {
> +     .id             = UINT_MAX,
> +     .compatible     = "arm,arm-v8",
> +     .init           = arm_cpu__vcpu_init,
> +};
> +
>  static struct kvm_arm_target target_aem_v8 = {
>       .id             = KVM_ARM_TARGET_AEM_V8,
>       .compatible     = "arm,arm-v8",
> @@ -43,7 +48,8 @@ static struct kvm_arm_target target_cortex_a57 = {
>  
>  static int arm_cpu__core_init(struct kvm *kvm)
>  {
> -     return (kvm_cpu__register_kvm_arm_target(&target_aem_v8) ||
> +     return (kvm_cpu__register_kvm_arm_target(&target_generic_v8) ||
> +             kvm_cpu__register_kvm_arm_target(&target_aem_v8) ||
>               kvm_cpu__register_kvm_arm_target(&target_foundation_v8) ||
>               kvm_cpu__register_kvm_arm_target(&target_cortex_a57));
>  }

(same thing like for v7 here)

> diff --git a/tools/kvm/arm/kvm-cpu.c b/tools/kvm/arm/kvm-cpu.c
> index aeaa4cf..6de5344 100644
> --- a/tools/kvm/arm/kvm-cpu.c
> +++ b/tools/kvm/arm/kvm-cpu.c
> @@ -13,7 +13,7 @@ int kvm_cpu__get_debug_fd(void)
>       return debug_fd;
>  }
>  
> -static struct kvm_arm_target *kvm_arm_targets[KVM_ARM_NUM_TARGETS];
> +static struct kvm_arm_target *kvm_arm_targets[KVM_ARM_NUM_TARGETS+1];

w/s issue

>  int kvm_cpu__register_kvm_arm_target(struct kvm_arm_target *target)
>  {
>       unsigned int i = 0;
> @@ -33,7 +33,8 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, 
> unsigned long cpu_id)
>       struct kvm_arm_target *target;
>       struct kvm_cpu *vcpu;
>       int coalesced_offset, mmap_size, err = -1;
> -     unsigned int i;
> +     unsigned int i, target_type;
> +     struct kvm_vcpu_init preferred_init;
>       struct kvm_vcpu_init vcpu_init = {
>               .features = ARM_VCPU_FEATURE_FLAGS(kvm, cpu_id)
>       };
> @@ -55,19 +56,47 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, 
> unsigned long cpu_id)
>       if (vcpu->kvm_run == MAP_FAILED)
>               die("unable to mmap vcpu fd");
>  
> -     /* Find an appropriate target CPU type. */
> -     for (i = 0; i < ARRAY_SIZE(kvm_arm_targets); ++i) {
> -             if (!kvm_arm_targets[i])
> -                     continue;
> -             target = kvm_arm_targets[i];
> -             vcpu_init.target = target->id;
> +     /*
> +      * If preferred target ioctl successful then use preferred target

            the                     is

> +      * else try each and every target type.
> +      */
> +     err = ioctl(kvm->vm_fd, KVM_ARM_PREFERRED_TARGET, &preferred_init);
> +     if (!err) {
> +             /* Match preferred target CPU type. */
> +             target = NULL;
> +             for (i = 0; i < ARRAY_SIZE(kvm_arm_targets); ++i) {
> +                     if (!kvm_arm_targets[i])
> +                             continue;
> +                     if (kvm_arm_targets[i]->id == preferred_init.target) {
> +                             target = kvm_arm_targets[i];
> +                             target_type = kvm_arm_targets[i]->id;
> +                             break;
> +                     }
> +             }
> +             if (!target) {
> +                     target = kvm_arm_targets[0];

As hinted above, I'd rather see a name for the magic 0 here or the
default target_generic referenced directly.

> +                     target_type = preferred_init.target;
> +             }
> +             vcpu_init.target = target_type;

I think you can get rid of the target_type variable at all:

if (!target) {
        target = &target_generic_v8;
        vcpu_init.target = preferred_init.target;
} else
        vcpu_init.target = target->id;

>               err = ioctl(vcpu->vcpu_fd, KVM_ARM_VCPU_INIT, &vcpu_init);
> -             if (!err)
> -                     break;
> +     } else {
> +             /* Find an appropriate target CPU type. */
> +             for (i = 0; i < ARRAY_SIZE(kvm_arm_targets); ++i) {
> +                     if (!kvm_arm_targets[i])
> +                             continue;
> +                     target = kvm_arm_targets[i];
> +                     target_type = target->id;
> +                     vcpu_init.target = target_type;

even more obvious here.

> +                     err = ioctl(vcpu->vcpu_fd, KVM_ARM_VCPU_INIT, 
> &vcpu_init);
> +                     if (!err)
> +                             break;
> +             }
> +             if (err)
> +                     die("Unable to find matching target");
>       }
>  
>       if (err || target->init(vcpu))
> -             die("Unable to initialise ARM vcpu");
> +             die("Unable to initialise vcpu");
>  
>       coalesced_offset = ioctl(kvm->sys_fd, KVM_CHECK_EXTENSION,
>                                KVM_CAP_COALESCED_MMIO);
> @@ -81,6 +110,7 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, 
> unsigned long cpu_id)
>       vcpu->cpu_type          = target->id;

If I am not mistaken, this value is bogus when we use PREFERRED_TARGET.
Please use vcpu_init.target here instead.

Regards,
Andre.

>       vcpu->cpu_compatible    = target->compatible;
>       vcpu->is_running        = true;
> +
>       return vcpu;
>  }
>  
> 
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