Re: [PATCH v1 1/2] xen/kexec: Find out whether an kexec type is loaded.

[Daniel Kiper <daniel.kiper@oracle.com>]

On Mon, Nov 14, 2016 at 05:12:52PM -0500, Konrad Rzeszutek Wilk wrote:
> The tools that use kexec are asynchronous in nature and do
> not keep state changes. As such provide an hypercall to find
> out whether an image has been loaded for either type.
>
> Note: No need to modify XSM as it has one size fits all
> check and does not check for subcommands.
>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
> v0: Internal version.
> v1: Dropped Reviewed-by, posting on xen-devel.
>
> CC: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> CC: Daniel Kiper <daniel.kiper@oracle.com>
> ---
>  tools/libxc/include/xenctrl.h |  8 ++++++++
>  tools/libxc/xc_kexec.c        | 27 +++++++++++++++++++++++++++
>  xen/common/kexec.c            | 25 +++++++++++++++++++++++++
>  xen/include/public/kexec.h    | 11 +++++++++++
>  4 files changed, 71 insertions(+)
>
> diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
> index 2c83544..aa5d798 100644
> --- a/tools/libxc/include/xenctrl.h
> +++ b/tools/libxc/include/xenctrl.h
> @@ -2574,6 +2574,14 @@ int xc_kexec_load(xc_interface *xch, uint8_t type, uint16_t arch,
>   */
>  int xc_kexec_unload(xc_interface *xch, int type);
>
> +/*
> + * Find out whether the image has been succesfully loaded.
> + *
> + * The can be either KEXEC_TYPE_DEFAULT or KEXEC_TYPE_CRASH.
> + * If zero is returned that means the image is loaded for the type.
> + */
> +int xc_kexec_status(xc_interface *xch, int type);
> +
>  typedef xenpf_resource_entry_t xc_resource_entry_t;
>
>  /*
> diff --git a/tools/libxc/xc_kexec.c b/tools/libxc/xc_kexec.c
> index 1cceb5d..95d36ff 100644
> --- a/tools/libxc/xc_kexec.c
> +++ b/tools/libxc/xc_kexec.c
> @@ -126,3 +126,30 @@ out:
>
>      return ret;
>  }
> +
> +int xc_kexec_status(xc_interface *xch, int type)
> +{
> +    DECLARE_HYPERCALL;
> +    DECLARE_HYPERCALL_BUFFER(xen_kexec_status_t, status);
> +    int ret = -1;
> +
> +    status = xc_hypercall_buffer_alloc(xch, status, sizeof(*status));
> +    if ( status == NULL )
> +    {
> +        PERROR("Count not alloc buffer for kexec status hypercall");

Could not? It looks that you copied this from existing code. Could you
send separate patch fixing this issue in two other places too?

> +        goto out;
> +    }
> +
> +    status->type = type;
> +
> +    hypercall.op = __HYPERVISOR_kexec_op;
> +    hypercall.arg[0] = KEXEC_CMD_kexec_status;
> +    hypercall.arg[1] = HYPERCALL_BUFFER_AS_ARG(status);
> +
> +    ret = do_xen_hypercall(xch, &hypercall);
> +
> +out:
> +    xc_hypercall_buffer_free(xch, status);
> +
> +    return ret;
> +}
> diff --git a/xen/common/kexec.c b/xen/common/kexec.c
> index c83d48f..1148f85 100644
> --- a/xen/common/kexec.c
> +++ b/xen/common/kexec.c
> @@ -1169,6 +1169,28 @@ static int kexec_unload(XEN_GUEST_HANDLE_PARAM(void) uarg)
>      return kexec_do_unload(&unload);
>  }
>
> +static int kexec_status(XEN_GUEST_HANDLE_PARAM(void) uarg)
> +{
> +    xen_kexec_status_t status;
> +    int base, bit, pos;
> +
> +    if ( unlikely(copy_from_guest(&status, uarg, 1)) )
> +        return -EFAULT;
> +
> +    if ( test_bit(KEXEC_FLAG_IN_PROGRESS, &kexec_flags) )
> +        return -EBUSY;
> +
> +    if ( kexec_load_get_bits(status.type, &base, &bit) )
> +        return -EINVAL;
> +
> +    pos = (test_bit(bit, &kexec_flags) != 0);
> +
> +    if ( !test_bit(base + pos, &kexec_flags) )
> +        return -ENOENT;
> +
> +    return 0;
> +}
> +
>  static int do_kexec_op_internal(unsigned long op,
>                                  XEN_GUEST_HANDLE_PARAM(void) uarg,
>                                  bool_t compat)
> @@ -1208,6 +1230,9 @@ static int do_kexec_op_internal(unsigned long op,
>      case KEXEC_CMD_kexec_unload:
>          ret = kexec_unload(uarg);
>          break;
> +    case KEXEC_CMD_kexec_status:
> +	ret = kexec_status(uarg);
> +	break;
>      }
>
>      return ret;
> diff --git a/xen/include/public/kexec.h b/xen/include/public/kexec.h
> index a6a0a88..29dcb5d 100644
> --- a/xen/include/public/kexec.h
> +++ b/xen/include/public/kexec.h
> @@ -227,6 +227,17 @@ typedef struct xen_kexec_unload {
>  } xen_kexec_unload_t;
>  DEFINE_XEN_GUEST_HANDLE(xen_kexec_unload_t);
>
> +/*
> + * Figure out whether we have an image loaded. An return value of
> + * zero indicates success while XEN_ENODEV implies no image loaded.

It seems to me that you thought about -ENOENT instead of XEN_ENODEV.

If you fix both things then Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

Daniel

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