Re: [Qemu-devel] [PATCH v7 3/4] kvm: add kvm_device_supported() helper function

[Sergey Fedorov <serge.fdrv@gmail.com>]

On 24/03/16 05:55, Peter Xu wrote:
> This can be used when probing whether KVM support specific device. Here,
> a raw vmfd is used.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>

Acked-by: Sergey Fedorov <serge.fdrv@gmail.com>

Kind regards,
Sergey


> ---
>  include/sysemu/kvm.h |  9 +++++++++
>  kvm-all.c            | 15 +++++++++++++++
>  2 files changed, 24 insertions(+)
>
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 6695fa7..0e18f15 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -306,6 +306,15 @@ void kvm_device_access(int fd, int group, uint64_t attr,
>   */
>  int kvm_create_device(KVMState *s, uint64_t type, bool test);
>  
> +/**
> + * kvm_device_supported - probe whether KVM supports specific device
> + *
> + * @vmfd: The fd handler for VM
> + * @type: type of device
> + *
> + * @return: true if supported, otherwise false.
> + */
> +bool kvm_device_supported(int vmfd, uint64_t type);
>  
>  /* Arch specific hooks */
>  
> diff --git a/kvm-all.c b/kvm-all.c
> index 44c0464..e7b66df 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -2339,6 +2339,21 @@ int kvm_create_device(KVMState *s, uint64_t type, bool test)
>      return test ? 0 : create_dev.fd;
>  }
>  
> +bool kvm_device_supported(int vmfd, uint64_t type)
> +{
> +    struct kvm_create_device create_dev = {
> +        .type = type,
> +        .fd = -1,
> +        .flags = KVM_CREATE_DEVICE_TEST,
> +    };
> +
> +    if (ioctl(vmfd, KVM_CHECK_EXTENSION, KVM_CAP_DEVICE_CTRL) <= 0) {
> +        return false;
> +    }
> +
> +    return (ioctl(vmfd, KVM_CREATE_DEVICE, &create_dev) >= 0);
> +}
> +
>  int kvm_set_one_reg(CPUState *cs, uint64_t id, void *source)
>  {
>      struct kvm_one_reg reg;