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authorStefano Stabellini <sstabellini@kernel.org>2017-10-30 15:40:54 -0700
committerBoris Ostrovsky <boris.ostrovsky@oracle.com>2017-10-31 09:05:53 -0400
commit2195046bfd69e487d9a76dc47840f15c8412840c (patch)
tree058ae0eb2533ac135b69894b159bb66010ea8df5 /drivers/xen
parent21968190991320c0d9b6d1280e7dfda420164db1 (diff)
xen/pvcalls: implement socket command and handle events
Send a PVCALLS_SOCKET command to the backend, use the masked req_prod_pvt as req_id. This way, req_id is guaranteed to be between 0 and PVCALLS_NR_REQ_PER_RING. We already have a slot in the rsp array ready for the response, and there cannot be two outstanding responses with the same req_id. Wait for the response by waiting on the inflight_req waitqueue and check for the req_id field in rsp[req_id]. Use atomic accesses and barriers to read the field. Note that the barriers are simple smp barriers (as opposed to virt barriers) because they are for internal frontend synchronization, not frontend<->backend communication. Once a response is received, clear the corresponding rsp slot by setting req_id to PVCALLS_INVALID_ID. Note that PVCALLS_INVALID_ID is invalid only from the frontend point of view. It is not part of the PVCalls protocol. pvcalls_front_event_handler is in charge of copying responses from the ring to the appropriate rsp slot. It is done by copying the body of the response first, then by copying req_id atomically. After the copies, wake up anybody waiting on waitqueue. socket_lock protects accesses to the ring. Convert the pointer to sock_mapping into an uintptr_t and use it as id for the new socket to pass to the backend. The struct will be fully initialized later on connect or bind. sock->sk->sk_send_head is not used for ip sockets: reuse the field to store a pointer to the struct sock_mapping corresponding to the socket. This way, we can easily get the struct sock_mapping from the struct socket. Signed-off-by: Stefano Stabellini <stefano@aporeto.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> CC: boris.ostrovsky@oracle.com CC: jgross@suse.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/pvcalls-front.c131
-rw-r--r--drivers/xen/pvcalls-front.h8
2 files changed, 139 insertions, 0 deletions
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index 1618502c1c66..326395d09e31 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -13,6 +13,10 @@
*/
#include <linux/module.h>
+#include <linux/net.h>
+#include <linux/socket.h>
+
+#include <net/sock.h>
#include <xen/events.h>
#include <xen/grant_table.h>
@@ -20,6 +24,8 @@
#include <xen/xenbus.h>
#include <xen/interface/io/pvcalls.h>
+#include "pvcalls-front.h"
+
#define PVCALLS_INVALID_ID UINT_MAX
#define PVCALLS_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
#define PVCALLS_NR_RSP_PER_RING __CONST_RING_SIZE(xen_pvcalls, XEN_PAGE_SIZE)
@@ -55,8 +61,58 @@ struct sock_mapping {
struct socket *sock;
};
+static inline int get_request(struct pvcalls_bedata *bedata, int *req_id)
+{
+ *req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1);
+ if (RING_FULL(&bedata->ring) ||
+ bedata->rsp[*req_id].req_id != PVCALLS_INVALID_ID)
+ return -EAGAIN;
+ return 0;
+}
+
static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
{
+ struct xenbus_device *dev = dev_id;
+ struct pvcalls_bedata *bedata;
+ struct xen_pvcalls_response *rsp;
+ uint8_t *src, *dst;
+ int req_id = 0, more = 0, done = 0;
+
+ if (dev == NULL)
+ return IRQ_HANDLED;
+
+ pvcalls_enter();
+ bedata = dev_get_drvdata(&dev->dev);
+ if (bedata == NULL) {
+ pvcalls_exit();
+ return IRQ_HANDLED;
+ }
+
+again:
+ while (RING_HAS_UNCONSUMED_RESPONSES(&bedata->ring)) {
+ rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons);
+
+ req_id = rsp->req_id;
+ dst = (uint8_t *)&bedata->rsp[req_id] + sizeof(rsp->req_id);
+ src = (uint8_t *)rsp + sizeof(rsp->req_id);
+ memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id));
+ /*
+ * First copy the rest of the data, then req_id. It is
+ * paired with the barrier when accessing bedata->rsp.
+ */
+ smp_wmb();
+ bedata->rsp[req_id].req_id = rsp->req_id;
+
+ done = 1;
+ bedata->ring.rsp_cons++;
+ }
+
+ RING_FINAL_CHECK_FOR_RESPONSES(&bedata->ring, more);
+ if (more)
+ goto again;
+ if (done)
+ wake_up(&bedata->inflight_req);
+ pvcalls_exit();
return IRQ_HANDLED;
}
@@ -65,6 +121,81 @@ static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
{
}
+int pvcalls_front_socket(struct socket *sock)
+{
+ struct pvcalls_bedata *bedata;
+ struct sock_mapping *map = NULL;
+ struct xen_pvcalls_request *req;
+ int notify, req_id, ret;
+
+ /*
+ * PVCalls only supports domain AF_INET,
+ * type SOCK_STREAM and protocol 0 sockets for now.
+ *
+ * Check socket type here, AF_INET and protocol checks are done
+ * by the caller.
+ */
+ if (sock->type != SOCK_STREAM)
+ return -EOPNOTSUPP;
+
+ pvcalls_enter();
+ if (!pvcalls_front_dev) {
+ pvcalls_exit();
+ return -EACCES;
+ }
+ bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
+
+ map = kzalloc(sizeof(*map), GFP_KERNEL);
+ if (map == NULL) {
+ pvcalls_exit();
+ return -ENOMEM;
+ }
+
+ spin_lock(&bedata->socket_lock);
+
+ ret = get_request(bedata, &req_id);
+ if (ret < 0) {
+ kfree(map);
+ spin_unlock(&bedata->socket_lock);
+ pvcalls_exit();
+ return ret;
+ }
+
+ /*
+ * sock->sk->sk_send_head is not used for ip sockets: reuse the
+ * field to store a pointer to the struct sock_mapping
+ * corresponding to the socket. This way, we can easily get the
+ * struct sock_mapping from the struct socket.
+ */
+ sock->sk->sk_send_head = (void *)map;
+ list_add_tail(&map->list, &bedata->socket_mappings);
+
+ req = RING_GET_REQUEST(&bedata->ring, req_id);
+ req->req_id = req_id;
+ req->cmd = PVCALLS_SOCKET;
+ req->u.socket.id = (uintptr_t) map;
+ req->u.socket.domain = AF_INET;
+ req->u.socket.type = SOCK_STREAM;
+ req->u.socket.protocol = IPPROTO_IP;
+
+ bedata->ring.req_prod_pvt++;
+ RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
+ spin_unlock(&bedata->socket_lock);
+ if (notify)
+ notify_remote_via_irq(bedata->irq);
+
+ wait_event(bedata->inflight_req,
+ READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
+
+ /* read req_id, then the content */
+ smp_rmb();
+ ret = bedata->rsp[req_id].ret;
+ bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
+
+ pvcalls_exit();
+ return ret;
+}
+
static const struct xenbus_device_id pvcalls_front_ids[] = {
{ "pvcalls" },
{ "" }
diff --git a/drivers/xen/pvcalls-front.h b/drivers/xen/pvcalls-front.h
new file mode 100644
index 000000000000..b7dabedf5ccb
--- /dev/null
+++ b/drivers/xen/pvcalls-front.h
@@ -0,0 +1,8 @@
+#ifndef __PVCALLS_FRONT_H__
+#define __PVCALLS_FRONT_H__
+
+#include <linux/net.h>
+
+int pvcalls_front_socket(struct socket *sock);
+
+#endif

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