Re: [Xen-devel] [PATCH v3] kexec: implement STATUS hypercall to check if image is loaded

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.01.17 at 18:29, <eric.devolder@xxxxxxxxxx> wrote:
> --- a/xen/common/kexec.c
> +++ b/xen/common/kexec.c
> @@ -1169,6 +1169,22 @@ 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;
> +
> +    if ( unlikely(copy_from_guest(&status, uarg, 1)) )
> +        return -EFAULT;
> +
> +    /* No need to check KEXEC_FLAG_IN_PROGRESS. */
> +
> +    if ( kexec_load_get_bits(status.type, &base, &bit) )
> +        return -EINVAL;
> +
> +    return test_bit(bit, &kexec_flags);

In the public header you promise to return zero or one here (unless
an error occurs), which requires the use of !!. Please see x86's
implementation of the function for how/when there can actually be
other non-zero values returned here (in particular all ones, which
would resolve to -EPERM).

> --- a/xen/include/public/kexec.h
> +++ b/xen/include/public/kexec.h
> @@ -227,6 +227,19 @@ 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. A return value of
> + * zero indicates no image loaded. A return value of one
> + * indicates an image is loaded. A negative return value
> + * indicates an error.
> + *
> + * Type must be one of KEXEC_TYPE_DEFAULT or KEXEC_TYPE_CRASH.
> + */
> +#define KEXEC_CMD_kexec_status 6
> +typedef struct xen_kexec_status {
> +    uint8_t type;
> +} xen_kexec_status_t;
> +DEFINE_XEN_GUEST_HANDLE(xen_kexec_status_t);
>  #else /* __XEN_INTERFACE_VERSION__ < 0x00040400 */

There was a blank line above here before your addition, and you
shouldn't eliminate it (making quickly scanning over the file harder).

I guess both items are simple enough to fix while committing.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel