Re: [PATCH for <= 5.4] xen/privcmd: allow fetching resource sizes

[Greg KH <greg@xxxxxxxxx>]

On Mon, Jan 18, 2021 at 03:04:26PM +0100, Roger Pau Monne wrote:
> commit ef3a575baf53571dc405ee4028e26f50856898e7 upstream
> 
> Allow issuing an IOCTL_PRIVCMD_MMAP_RESOURCE ioctl with num = 0 and
> addr = 0 in order to fetch the size of a specific resource.
> 
> Add a shortcut to the default map resource path, since fetching the
> size requires no address to be passed in, and thus no VMA to setup.
> 
> This is missing from the initial implementation, and causes issues
> when mapping resources that don't have fixed or known sizes.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
> Tested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # >= 4.18
> Link: https://lore.kernel.org/r/20210112115358.23346-1-roger.pau@xxxxxxxxxx
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
> ---
>  drivers/xen/privcmd.c | 25 +++++++++++++++++++------
>  1 file changed, 19 insertions(+), 6 deletions(-)

Now queued up, thanks.

greg k-h