Re: [Xen-devel] [PATCH v4 07/18] xen/pvcalls: implement socket command

From: Stefano Stabellini
Date: Wed Jun 21 2017 - 16:17:07 EST


On Tue, 20 Jun 2017, Roger Pau Monnà wrote:
> On Thu, Jun 15, 2017 at 12:09:36PM -0700, Stefano Stabellini wrote:
> > Just reply with success to the other end for now. Delay the allocation
> > of the actual socket to bind and/or connect.
> >
> > Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
> > CC: boris.ostrovsky@xxxxxxxxxx
> > CC: jgross@xxxxxxxx
> > ---
> > drivers/xen/pvcalls-back.c | 27 +++++++++++++++++++++++++++
> > 1 file changed, 27 insertions(+)
> >
> > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> > index 437c2ad..953458b 100644
> > --- a/drivers/xen/pvcalls-back.c
> > +++ b/drivers/xen/pvcalls-back.c
> > @@ -12,12 +12,17 @@
> > * GNU General Public License for more details.
> > */
> >
> > +#include <linux/inet.h>
> > #include <linux/kthread.h>
> > #include <linux/list.h>
> > #include <linux/radix-tree.h>
> > #include <linux/module.h>
> > #include <linux/semaphore.h>
> > #include <linux/wait.h>
> > +#include <net/sock.h>
> > +#include <net/inet_common.h>
> > +#include <net/inet_connection_sock.h>
> > +#include <net/request_sock.h>
> >
> > #include <xen/events.h>
> > #include <xen/grant_table.h>
> > @@ -54,6 +59,28 @@ struct pvcalls_fedata {
> > static int pvcalls_back_socket(struct xenbus_device *dev,
> > struct xen_pvcalls_request *req)
> > {
> > + struct pvcalls_fedata *fedata;
> > + int ret;
> > + struct xen_pvcalls_response *rsp;
> > +
> > + fedata = dev_get_drvdata(&dev->dev);
> > +
> > + if (req->u.socket.domain != AF_INET ||
> > + req->u.socket.type != SOCK_STREAM ||
> > + (req->u.socket.protocol != IPPROTO_IP &&
> > + req->u.socket.protocol != AF_INET))
> > + ret = -EAFNOSUPPORT;
>
> Sorry for jumping into this out of the blue, but shouldn't all the
> constants used above be part of the protocol? AF_INET/SOCK_STREAM/...
> are all part of POSIX, but their specific value is not defined in the
> standard, hence we should have XEN_AF_INET/XEN_SOCK_STREAM/... Or am I
> just missing something?

The values of these constants for the pvcalls protocol are defined by
docs/misc/pvcalls.markdown under "Socket families and address format".

They happen to be the same as the ones defined by Linux as AF_INET,
SOCK_STREAM, etc, so in Linux I am just using those, but that is just an
implementation detail internal to the Linux kernel driver. What is
important from the protocol ABI perspective are the values defined by
docs/misc/pvcalls.markdown.