Re: [PATCH 3/8] 9pfs/xen: implement msize_limit callback

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

Hi Stefano,

would you have a chance to look at this Xen patch 3 and patch 7 whether I am 
doing it right for Xen?

/Christian

On Wednesday, 27 May 2026 23:15:25 CEST Christian Schoenebeck wrote:
> Add and implement the msize_limit callback for the Xen transport.
> 
> The limit is calculated using XEN_FLEX_RING_SIZE() based on the
> negotiated ring_order. For the theoretical maximum ring_order of 9,
> this results in a maximum 'msize' of 1048576 bytes (1 MiB).
> 
> Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
> ---
>  hw/9pfs/xen-9p-backend.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/hw/9pfs/xen-9p-backend.c b/hw/9pfs/xen-9p-backend.c
> index ca0fff5fa9..94654022fe 100644
> --- a/hw/9pfs/xen-9p-backend.c
> +++ b/hw/9pfs/xen-9p-backend.c
> @@ -250,12 +250,19 @@ static void xen_9pfs_push_and_notify(V9fsPDU *pdu)
>      qemu_bh_schedule(ring->bh);
>  }
> 
> +static size_t xen_9p_msize_limit(V9fsState *s)
> +{
> +    Xen9pfsDev *xen_9pfs = container_of(s, Xen9pfsDev, state);
> +    return XEN_FLEX_RING_SIZE(xen_9pfs->rings[0].ring_order);
> +}
> +
>  static const V9fsTransport xen_9p_transport = {
>      .pdu_vmarshal = xen_9pfs_pdu_vmarshal,
>      .pdu_vunmarshal = xen_9pfs_pdu_vunmarshal,
>      .init_in_iov_from_pdu = xen_9pfs_init_in_iov_from_pdu,
>      .init_out_iov_from_pdu = xen_9pfs_init_out_iov_from_pdu,
>      .push_and_notify = xen_9pfs_push_and_notify,
> +    .msize_limit = xen_9p_msize_limit,
>  };
> 
>  static int xen_9pfs_init(struct XenLegacyDevice *xendev)