[PATCH v4 00/18] introduce the Xen PV Calls backend

[PATCH v4 00/18] introduce the Xen PV Calls backend

[Stefano Stabellini]

Hi all,

this series introduces the backend for the newly introduced PV Calls
procotol.

PV Calls is a paravirtualized protocol that allows the implementation of
a set of POSIX functions in a different domain. The PV Calls frontend
sends POSIX function calls to the backend, which implements them and
returns a value to the frontend and acts on the function call.

For more information about PV Calls, please read:

https://xenbits.xen.org/docs/unstable/misc/pvcalls.html

I tried to split the source code into small pieces to make it easier to
read and understand. Please review!


Changes in v4:
- add reviewed-bys
- fix return values of many functions
- remove pointless initializers
- print a warning if ring_order > MAX_RING_ORDER
- remove map->ioworker.cpu
- use queue_work instead of queue_work_on
- add sock_release() on error paths where appropriate
- add a comment in __pvcalls_back_accept about racing with
  pvcalls_back_accept and atomicity of reqcopy
- remove unneded (void*) casts
- remove unneded {}
- fix backend_disconnect if !mappass
- remove pointless continue in backend_disconnect
- remove pointless memset of &pvcalls_back_global
- pass *opaque to pvcalls_conn_back_read
- improve WARN_ON in pvcalls_conn_back_read
- fix error checks in pvcalls_conn_back_write
- XEN_PVCALLS_BACKEND depends on XEN_BACKEND
- rename priv to fedata across all patches

Changes in v3:
- added reviewed-bys
- return err from pvcalls_back_probe
- remove old comments
- use a xenstore transaction in pvcalls_back_probe
- ignore errors from xenbus_switch_state
- rename pvcalls_back_priv to pvcalls_fedata
- remove addr from backend_connect
- remove priv->work, add comment about theoretical race
- use IPPROTO_IP
- refactor active socket allocation in a single new function

Changes in v2:
- allocate one ioworker per socket (rather than 1 per vcpu)
- rename privs to frontends
- add newlines
- define "1" in the public header
- better error returns in pvcalls_back_probe
- do not set XenbusStateClosed twice in set_backend_state
- add more comments
- replace rw_semaphore with semaphore
- rename pvcallss to socket_lock
- move xenbus_map_ring_valloc closer to first use in backend_connect
- use more traditional return codes from pvcalls_back_handle_cmd and
  callees
- remove useless dev == NULL checks
- replace lock_sock with more appropriate and fine grained socket locks


Stefano Stabellini (18):
      xen: introduce the pvcalls interface header
      xen/pvcalls: introduce the pvcalls xenbus backend
      xen/pvcalls: initialize the module and register the xenbus backend
      xen/pvcalls: xenbus state handling
      xen/pvcalls: connect to a frontend
      xen/pvcalls: handle commands from the frontend
      xen/pvcalls: implement socket command
      xen/pvcalls: implement connect command
      xen/pvcalls: implement bind command
      xen/pvcalls: implement listen command
      xen/pvcalls: implement accept command
      xen/pvcalls: implement poll command
      xen/pvcalls: implement release command
      xen/pvcalls: disconnect and module_exit
      xen/pvcalls: implement the ioworker functions
      xen/pvcalls: implement read
      xen/pvcalls: implement write
      xen: introduce a Kconfig option to enable the pvcalls backend

 drivers/xen/Kconfig                |   12 +
 drivers/xen/Makefile               |    1 +
 drivers/xen/pvcalls-back.c         | 1232 ++++++++++++++++++++++++++++++++++++
 include/xen/interface/io/pvcalls.h |  121 ++++
 include/xen/interface/io/ring.h    |    2 +
 5 files changed, 1368 insertions(+)
 create mode 100644 drivers/xen/pvcalls-back.c
 create mode 100644 include/xen/interface/io/pvcalls.h

[PATCH v4 01/18] xen: introduce the pvcalls interface header

[Stefano Stabellini]

Introduce the C header file which defines the PV Calls interface. It is
imported from xen/include/public/io/pvcalls.h.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
CC: konrad.wilk@oracle.com
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 include/xen/interface/io/pvcalls.h | 121 +++++++++++++++++++++++++++++++++++++
 include/xen/interface/io/ring.h    |   2 +
 2 files changed, 123 insertions(+)
 create mode 100644 include/xen/interface/io/pvcalls.h

diff --git a/include/xen/interface/io/pvcalls.h b/include/xen/interface/io/pvcalls.h
new file mode 100644
index 0000000..ccf97b8
--- /dev/null
+++ b/include/xen/interface/io/pvcalls.h
@@ -0,0 +1,121 @@
+#ifndef __XEN_PUBLIC_IO_XEN_PVCALLS_H__
+#define __XEN_PUBLIC_IO_XEN_PVCALLS_H__
+
+#include <linux/net.h>
+#include <xen/interface/io/ring.h>
+#include <xen/interface/grant_table.h>
+
+/* "1" means socket, connect, release, bind, listen, accept and poll */
+#define XENBUS_FUNCTIONS_CALLS "1"
+
+/*
+ * See docs/misc/pvcalls.markdown in xen.git for the full specification:
+ * https://xenbits.xen.org/docs/unstable/misc/pvcalls.html
+ */
+struct pvcalls_data_intf {
+    RING_IDX in_cons, in_prod, in_error;
+
+    uint8_t pad1[52];
+
+    RING_IDX out_cons, out_prod, out_error;
+
+    uint8_t pad2[52];
+
+    RING_IDX ring_order;
+    grant_ref_t ref[];
+};
+DEFINE_XEN_FLEX_RING(pvcalls);
+
+#define PVCALLS_SOCKET         0
+#define PVCALLS_CONNECT        1
+#define PVCALLS_RELEASE        2
+#define PVCALLS_BIND           3
+#define PVCALLS_LISTEN         4
+#define PVCALLS_ACCEPT         5
+#define PVCALLS_POLL           6
+
+struct xen_pvcalls_request {
+    uint32_t req_id; /* private to guest, echoed in response */
+    uint32_t cmd;    /* command to execute */
+    union {
+        struct xen_pvcalls_socket {
+            uint64_t id;
+            uint32_t domain;
+            uint32_t type;
+            uint32_t protocol;
+        } socket;
+        struct xen_pvcalls_connect {
+            uint64_t id;
+            uint8_t addr[28];
+            uint32_t len;
+            uint32_t flags;
+            grant_ref_t ref;
+            uint32_t evtchn;
+        } connect;
+        struct xen_pvcalls_release {
+            uint64_t id;
+            uint8_t reuse;
+        } release;
+        struct xen_pvcalls_bind {
+            uint64_t id;
+            uint8_t addr[28];
+            uint32_t len;
+        } bind;
+        struct xen_pvcalls_listen {
+            uint64_t id;
+            uint32_t backlog;
+        } listen;
+        struct xen_pvcalls_accept {
+            uint64_t id;
+            uint64_t id_new;
+            grant_ref_t ref;
+            uint32_t evtchn;
+        } accept;
+        struct xen_pvcalls_poll {
+            uint64_t id;
+        } poll;
+        /* dummy member to force sizeof(struct xen_pvcalls_request)
+         * to match across archs */
+        struct xen_pvcalls_dummy {
+            uint8_t dummy[56];
+        } dummy;
+    } u;
+};
+
+struct xen_pvcalls_response {
+    uint32_t req_id;
+    uint32_t cmd;
+    int32_t ret;
+    uint32_t pad;
+    union {
+        struct _xen_pvcalls_socket {
+            uint64_t id;
+        } socket;
+        struct _xen_pvcalls_connect {
+            uint64_t id;
+        } connect;
+        struct _xen_pvcalls_release {
+            uint64_t id;
+        } release;
+        struct _xen_pvcalls_bind {
+            uint64_t id;
+        } bind;
+        struct _xen_pvcalls_listen {
+            uint64_t id;
+        } listen;
+        struct _xen_pvcalls_accept {
+            uint64_t id;
+        } accept;
+        struct _xen_pvcalls_poll {
+            uint64_t id;
+        } poll;
+        struct _xen_pvcalls_dummy {
+            uint8_t dummy[8];
+        } dummy;
+    } u;
+};
+
+DEFINE_RING_TYPES(xen_pvcalls, struct xen_pvcalls_request,
+                  struct xen_pvcalls_response);
+
+#endif
diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h
index c794568..e547088 100644
--- a/include/xen/interface/io/ring.h
+++ b/include/xen/interface/io/ring.h
@@ -9,6 +9,8 @@
 #ifndef __XEN_PUBLIC_IO_RING_H__
 #define __XEN_PUBLIC_IO_RING_H__
 
+#include <xen/interface/grant_table.h>
+
 typedef unsigned int RING_IDX;
 
 /* Round a 32-bit unsigned constant down to the nearest power of two. */
-- 
1.9.1

[PATCH v4 02/18] xen/pvcalls: introduce the pvcalls xenbus backend

[Stefano Stabellini]

Introduce a xenbus backend for the pvcalls protocol, as defined by
https://xenbits.xen.org/docs/unstable/misc/pvcalls.html.

This patch only adds the stubs, the code will be added by the following
patches.

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
---
 drivers/xen/pvcalls-back.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 drivers/xen/pvcalls-back.c

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
new file mode 100644
index 0000000..f3d0daa
--- /dev/null
+++ b/drivers/xen/pvcalls-back.c
@@ -0,0 +1,61 @@
+/*
+ * (c) 2017 Stefano Stabellini <stefano@aporeto.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#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 <xen/events.h>
+#include <xen/grant_table.h>
+#include <xen/xen.h>
+#include <xen/xenbus.h>
+#include <xen/interface/io/pvcalls.h>
+
+static int pvcalls_back_probe(struct xenbus_device *dev,
+			      const struct xenbus_device_id *id)
+{
+	return 0;
+}
+
+static void pvcalls_back_changed(struct xenbus_device *dev,
+				 enum xenbus_state frontend_state)
+{
+}
+
+static int pvcalls_back_remove(struct xenbus_device *dev)
+{
+	return 0;
+}
+
+static int pvcalls_back_uevent(struct xenbus_device *xdev,
+			       struct kobj_uevent_env *env)
+{
+	return 0;
+}
+
+static const struct xenbus_device_id pvcalls_back_ids[] = {
+	{ "pvcalls" },
+	{ "" }
+};
+
+static struct xenbus_driver pvcalls_back_driver = {
+	.ids = pvcalls_back_ids,
+	.probe = pvcalls_back_probe,
+	.remove = pvcalls_back_remove,
+	.uevent = pvcalls_back_uevent,
+	.otherend_changed = pvcalls_back_changed,
+};
-- 
1.9.1

[PATCH v4 03/18] xen/pvcalls: initialize the module and register the xenbus backend

[Stefano Stabellini]

Keep a list of connected frontends. Use a semaphore to protect list
accesses.

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
---
 drivers/xen/pvcalls-back.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index f3d0daa..9044cf2 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -25,6 +25,11 @@
 #include <xen/xenbus.h>
 #include <xen/interface/io/pvcalls.h>
 
+struct pvcalls_back_global {
+	struct list_head frontends;
+	struct semaphore frontends_lock;
+} pvcalls_back_global;
+
 static int pvcalls_back_probe(struct xenbus_device *dev,
 			      const struct xenbus_device_id *id)
 {
@@ -59,3 +64,20 @@ static int pvcalls_back_uevent(struct xenbus_device *xdev,
 	.uevent = pvcalls_back_uevent,
 	.otherend_changed = pvcalls_back_changed,
 };
+
+static int __init pvcalls_back_init(void)
+{
+	int ret;
+
+	if (!xen_domain())
+		return -ENODEV;
+
+	ret = xenbus_register_backend(&pvcalls_back_driver);
+	if (ret < 0)
+		return ret;
+
+	sema_init(&pvcalls_back_global.frontends_lock, 1);
+	INIT_LIST_HEAD(&pvcalls_back_global.frontends);
+	return 0;
+}
+module_init(pvcalls_back_init);
-- 
1.9.1

[PATCH v4 04/18] xen/pvcalls: xenbus state handling

[Stefano Stabellini]

Introduce the code to handle xenbus state changes.

Implement the probe function for the pvcalls backend. Write the
supported versions, max-page-order and function-calls nodes to xenstore,
as required by the protocol.

Introduce stub functions for disconnecting/connecting to a frontend.

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
---
 drivers/xen/pvcalls-back.c | 152 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 9044cf2..7bce750 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -25,20 +25,172 @@
 #include <xen/xenbus.h>
 #include <xen/interface/io/pvcalls.h>
 
+#define PVCALLS_VERSIONS "1"
+#define MAX_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
+
 struct pvcalls_back_global {
 	struct list_head frontends;
 	struct semaphore frontends_lock;
 } pvcalls_back_global;
 
+static int backend_connect(struct xenbus_device *dev)
+{
+	return 0;
+}
+
+static int backend_disconnect(struct xenbus_device *dev)
+{
+	return 0;
+}
+
 static int pvcalls_back_probe(struct xenbus_device *dev,
 			      const struct xenbus_device_id *id)
 {
+	int err, abort;
+	struct xenbus_transaction xbt;
+
+again:
+	abort = 1;
+
+	err = xenbus_transaction_start(&xbt);
+	if (err) {
+		pr_warn("%s cannot create xenstore transaction\n", __func__);
+		return err;
+	}
+
+	err = xenbus_printf(xbt, dev->nodename, "versions", "%s",
+			    PVCALLS_VERSIONS);
+	if (err) {
+		pr_warn("%s write out 'version' failed\n", __func__);
+		goto abort;
+	}
+
+	err = xenbus_printf(xbt, dev->nodename, "max-page-order", "%u",
+			    MAX_RING_ORDER);
+	if (err) {
+		pr_warn("%s write out 'max-page-order' failed\n", __func__);
+		goto abort;
+	}
+
+	err = xenbus_printf(xbt, dev->nodename, "function-calls",
+			    XENBUS_FUNCTIONS_CALLS);
+	if (err) {
+		pr_warn("%s write out 'function-calls' failed\n", __func__);
+		goto abort;
+	}
+
+	abort = 0;
+abort:
+	err = xenbus_transaction_end(xbt, abort);
+	if (err) {
+		if (err == -EAGAIN && !abort)
+			goto again;
+		pr_warn("%s cannot complete xenstore transaction\n", __func__);
+		return err;
+	}
+
+	xenbus_switch_state(dev, XenbusStateInitWait);
+
 	return 0;
 }
 
+static void set_backend_state(struct xenbus_device *dev,
+			      enum xenbus_state state)
+{
+	while (dev->state != state) {
+		switch (dev->state) {
+		case XenbusStateClosed:
+			switch (state) {
+			case XenbusStateInitWait:
+			case XenbusStateConnected:
+				xenbus_switch_state(dev, XenbusStateInitWait);
+				break;
+			case XenbusStateClosing:
+				xenbus_switch_state(dev, XenbusStateClosing);
+				break;
+			default:
+				__WARN();
+			}
+			break;
+		case XenbusStateInitWait:
+		case XenbusStateInitialised:
+			switch (state) {
+			case XenbusStateConnected:
+				backend_connect(dev);
+				xenbus_switch_state(dev, XenbusStateConnected);
+				break;
+			case XenbusStateClosing:
+			case XenbusStateClosed:
+				xenbus_switch_state(dev, XenbusStateClosing);
+				break;
+			default:
+				__WARN();
+			}
+			break;
+		case XenbusStateConnected:
+			switch (state) {
+			case XenbusStateInitWait:
+			case XenbusStateClosing:
+			case XenbusStateClosed:
+				down(&pvcalls_back_global.frontends_lock);
+				backend_disconnect(dev);
+				up(&pvcalls_back_global.frontends_lock);
+				xenbus_switch_state(dev, XenbusStateClosing);
+				break;
+			default:
+				__WARN();
+			}
+			break;
+		case XenbusStateClosing:
+			switch (state) {
+			case XenbusStateInitWait:
+			case XenbusStateConnected:
+			case XenbusStateClosed:
+				xenbus_switch_state(dev, XenbusStateClosed);
+				break;
+			default:
+				__WARN();
+			}
+			break;
+		default:
+			__WARN();
+		}
+	}
+}
+
 static void pvcalls_back_changed(struct xenbus_device *dev,
 				 enum xenbus_state frontend_state)
 {
+	switch (frontend_state) {
+	case XenbusStateInitialising:
+		set_backend_state(dev, XenbusStateInitWait);
+		break;
+
+	case XenbusStateInitialised:
+	case XenbusStateConnected:
+		set_backend_state(dev, XenbusStateConnected);
+		break;
+
+	case XenbusStateClosing:
+		set_backend_state(dev, XenbusStateClosing);
+		break;
+
+	case XenbusStateClosed:
+		set_backend_state(dev, XenbusStateClosed);
+		if (xenbus_dev_is_online(dev))
+			break;
+		device_unregister(&dev->dev);
+		break;
+	case XenbusStateUnknown:
+		set_backend_state(dev, XenbusStateClosed);
+		device_unregister(&dev->dev);
+		break;
+
+	default:
+		xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
+				 frontend_state);
+		break;
+	}
 }
 
 static int pvcalls_back_remove(struct xenbus_device *dev)
-- 
1.9.1

[PATCH v4 05/18] xen/pvcalls: connect to a frontend

[Stefano Stabellini]

Introduce a per-frontend data structure named pvcalls_fedata. It
contains pointers to the command ring, its event channel, a list of
active sockets and a tree of passive sockets (passing sockets need to be
looked up from the id on listen, accept and poll commands, while active
sockets only on release).

It also has an unbound workqueue to schedule the work of parsing and
executing commands on the command ring. socket_lock protects the two
lists. In pvcalls_back_global, keep a list of connected frontends.

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
---
 drivers/xen/pvcalls-back.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 7bce750..e4c2e46 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -33,9 +33,101 @@ struct pvcalls_back_global {
 	struct semaphore frontends_lock;
 } pvcalls_back_global;
 
+/*
+ * Per-frontend data structure. It contains pointers to the command
+ * ring, its event channel, a list of active sockets and a tree of
+ * passive sockets.
+ */
+struct pvcalls_fedata {
+	struct list_head list;
+	struct xenbus_device *dev;
+	struct xen_pvcalls_sring *sring;
+	struct xen_pvcalls_back_ring ring;
+	int irq;
+	struct list_head socket_mappings;
+	struct radix_tree_root socketpass_mappings;
+	struct semaphore socket_lock;
+	struct workqueue_struct *wq;
+	struct work_struct register_work;
+};
+
+static void pvcalls_back_work(struct work_struct *work)
+{
+}
+
+static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
+{
+	return IRQ_HANDLED;
+}
+
 static int backend_connect(struct xenbus_device *dev)
 {
+	int err, evtchn;
+	grant_ref_t ring_ref;
+	struct pvcalls_fedata *fedata = NULL;
+
+	fedata = kzalloc(sizeof(struct pvcalls_fedata), GFP_KERNEL);
+	if (!fedata)
+		return -ENOMEM;
+
+	err = xenbus_scanf(XBT_NIL, dev->otherend, "port", "%u",
+			   &evtchn);
+	if (err != 1) {
+		err = -EINVAL;
+		xenbus_dev_fatal(dev, err, "reading %s/event-channel",
+				 dev->otherend);
+		goto error;
+	}
+
+	err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref", "%u", &ring_ref);
+	if (err != 1) {
+		err = -EINVAL;
+		xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
+				 dev->otherend);
+		goto error;
+	}
+
+	err = bind_interdomain_evtchn_to_irqhandler(dev->otherend_id, evtchn,
+						    pvcalls_back_event, 0,
+						    "pvcalls-backend", dev);
+	if (err < 0)
+		goto error;
+	fedata->irq = err;
+
+	fedata->wq = alloc_workqueue("pvcalls_back_wq", WQ_UNBOUND, 1);
+	if (!fedata->wq) {
+		err = -ENOMEM;
+		goto error;
+	}
+
+	err = xenbus_map_ring_valloc(dev, &ring_ref, 1, (void**)&fedata->sring);
+	if (err < 0)
+		goto error;
+
+	BACK_RING_INIT(&fedata->ring, fedata->sring, XEN_PAGE_SIZE * 1);
+	fedata->dev = dev;
+
+	INIT_WORK(&fedata->register_work, pvcalls_back_work);
+	INIT_LIST_HEAD(&fedata->socket_mappings);
+	INIT_RADIX_TREE(&fedata->socketpass_mappings, GFP_KERNEL);
+	sema_init(&fedata->socket_lock, 1);
+	dev_set_drvdata(&dev->dev, fedata);
+
+	down(&pvcalls_back_global.frontends_lock);
+	list_add_tail(&fedata->list, &pvcalls_back_global.frontends);
+	up(&pvcalls_back_global.frontends_lock);
+	queue_work(fedata->wq, &fedata->register_work);
+
 	return 0;
+
+ error:
+	if (fedata->sring != NULL)
+		xenbus_unmap_ring_vfree(dev, fedata->sring);
+	if (fedata->wq)
+		destroy_workqueue(fedata->wq);
+	unbind_from_irqhandler(fedata->irq, dev);
+	kfree(fedata);
+	return err;
 }
 
 static int backend_disconnect(struct xenbus_device *dev)
-- 
1.9.1

[PATCH v4 06/18] xen/pvcalls: handle commands from the frontend

[Stefano Stabellini]

When the other end notifies us that there are commands to be read
(pvcalls_back_event), wake up the backend thread to parse the command.

The command ring works like most other Xen rings, so use the usual
ring macros to read and write to it. The functions implementing the
commands are empty stubs for now.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 119 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index e4c2e46..437c2ad 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -51,12 +51,131 @@ struct pvcalls_fedata {
 	struct work_struct register_work;
 };
 
+static int pvcalls_back_socket(struct xenbus_device *dev,
+		struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_connect(struct xenbus_device *dev,
+				struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_release(struct xenbus_device *dev,
+				struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_bind(struct xenbus_device *dev,
+			     struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_listen(struct xenbus_device *dev,
+			       struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_accept(struct xenbus_device *dev,
+			       struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_poll(struct xenbus_device *dev,
+			     struct xen_pvcalls_request *req)
+{
+	return 0;
+}
+
+static int pvcalls_back_handle_cmd(struct xenbus_device *dev,
+				   struct xen_pvcalls_request *req)
+{
+	int ret = 0;
+
+	switch (req->cmd) {
+	case PVCALLS_SOCKET:
+		ret = pvcalls_back_socket(dev, req);
+		break;
+	case PVCALLS_CONNECT:
+		ret = pvcalls_back_connect(dev, req);
+		break;
+	case PVCALLS_RELEASE:
+		ret = pvcalls_back_release(dev, req);
+		break;
+	case PVCALLS_BIND:
+		ret = pvcalls_back_bind(dev, req);
+		break;
+	case PVCALLS_LISTEN:
+		ret = pvcalls_back_listen(dev, req);
+		break;
+	case PVCALLS_ACCEPT:
+		ret = pvcalls_back_accept(dev, req);
+		break;
+	case PVCALLS_POLL:
+		ret = pvcalls_back_poll(dev, req);
+		break;
+	default:
+		ret = -ENOTSUPP;
+		break;
+	}
+	return ret;
+}
+
 static void pvcalls_back_work(struct work_struct *work)
 {
+	struct pvcalls_fedata *fedata = container_of(work,
+		struct pvcalls_fedata, register_work);
+	int notify, notify_all = 0, more = 1;
+	struct xen_pvcalls_request req;
+	struct xenbus_device *dev = fedata->dev;
+
+	while (more) {
+		while (RING_HAS_UNCONSUMED_REQUESTS(&fedata->ring)) {
+			RING_COPY_REQUEST(&fedata->ring,
+					  fedata->ring.req_cons++,
+					  &req);
+
+			if (!pvcalls_back_handle_cmd(dev, &req)) {
+				RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(
+					&fedata->ring, notify);
+				notify_all += notify;
+			}
+		}
+
+		if (notify_all)
+			notify_remote_via_irq(fedata->irq);
+
+		RING_FINAL_CHECK_FOR_REQUESTS(&fedata->ring, more);
+	}
 }
 
 static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
 {
+	struct xenbus_device *dev = dev_id;
+	struct pvcalls_fedata *fedata = NULL;
+
+	if (dev == NULL)
+		return IRQ_HANDLED;
+
+	fedata = dev_get_drvdata(&dev->dev);
+	if (fedata == NULL)
+		return IRQ_HANDLED;
+
+	/*
+	 * TODO: a small theoretical race exists if we try to queue work
+	 * after pvcalls_back_work checked for final requests and before
+	 * it returns. The queuing will fail, and pvcalls_back_work
+	 * won't do the work because it is about to return. In that
+	 * case, we lose the notification.
+	 */
+	queue_work(fedata->wq, &fedata->register_work);
+
 	return IRQ_HANDLED;
 }
 
-- 
1.9.1

[PATCH v4 07/18] xen/pvcalls: implement socket command

[Stefano Stabellini]

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@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 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;
+	else
+		ret = 0;
+
+	/* leave the actual socket allocation for later */
+
+	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
+	rsp->req_id = req->req_id;
+	rsp->cmd = req->cmd;
+	rsp->u.socket.id = req->u.socket.id;
+	rsp->ret = ret;
+
 	return 0;
 }
 
-- 
1.9.1

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

[Boris Ostrovsky]

On 06/15/2017 03:09 PM, 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@aporeto.com>
> CC: boris.ostrovsky@oracle.com
> CC: jgross@suse.com

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

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

[Roger Pau Monné]

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@aporeto.com>
> CC: boris.ostrovsky@oracle.com
> CC: jgross@suse.com
> ---
>  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?

Roger.

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

[Stefano Stabellini]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 2464 bytes --]

On Tue, 20 Jun 2017, Roger Pau Monné 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@aporeto.com>
> > CC: boris.ostrovsky@oracle.com
> > CC: jgross@suse.com
> > ---
> >  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.

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

[Roger Pau Monné]

On Wed, Jun 21, 2017 at 01:16:56PM -0700, Stefano Stabellini wrote:
> On Tue, 20 Jun 2017, Roger Pau Monné 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@aporeto.com>
> > > CC: boris.ostrovsky@oracle.com
> > > CC: jgross@suse.com
> > > ---
> > >  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.

Oh I see. I still think this should be part of the public pvcalls.h
header, and that the error codes should be the ones defined in
public/errno.h (or else also added to the pvcalls header).

Roger.

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

[Stefano Stabellini]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 3983 bytes --]

On Thu, 22 Jun 2017, Roger Pau Monné wrote:
> On Wed, Jun 21, 2017 at 01:16:56PM -0700, Stefano Stabellini wrote:
> > On Tue, 20 Jun 2017, Roger Pau Monné 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@aporeto.com>
> > > > CC: boris.ostrovsky@oracle.com
> > > > CC: jgross@suse.com
> > > > ---
> > > >  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.
> 
> Oh I see. I still think this should be part of the public pvcalls.h
> header, and that the error codes should be the ones defined in
> public/errno.h (or else also added to the pvcalls header).

This was done differently in the past, but now that we have a formal
process, a person in charge of new PV drivers reviews, and design
documents with clearly spelled out ABIs, I consider the design docs
under docs/misc as the official specification. We don't need headers
anymore, they are redundant. In fact, we cannot have two specifications,
and the design docs are certainly the official ones (we don't want the
specs to be written as header files in C). To me, the headers under
xen/include/public/io/ are optional helpers. It doesn't matter what's in
there, or if frontends and backends use them or not.

There is really an argument for removing those headers, because they
might get out of sync with the spec by mistake, and in those cases, then
we really end up with two specifications for the same protocol. I would
be in favor of `git rm'ing all files under xen/include/public/io/ for
which we have a complete design doc under docs/misc.

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

[Andrew Cooper]

On 22/06/17 19:29, Stefano Stabellini wrote:
> On Thu, 22 Jun 2017, Roger Pau Monné wrote:
>> On Wed, Jun 21, 2017 at 01:16:56PM -0700, Stefano Stabellini wrote:
>>> On Tue, 20 Jun 2017, Roger Pau Monné 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@aporeto.com>
>>>>> CC: boris.ostrovsky@oracle.com
>>>>> CC: jgross@suse.com
>>>>> ---
>>>>>  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.
>> Oh I see. I still think this should be part of the public pvcalls.h
>> header, and that the error codes should be the ones defined in
>> public/errno.h (or else also added to the pvcalls header).
> This was done differently in the past, but now that we have a formal
> process, a person in charge of new PV drivers reviews, and design
> documents with clearly spelled out ABIs, I consider the design docs
> under docs/misc as the official specification. We don't need headers
> anymore, they are redundant. In fact, we cannot have two specifications,
> and the design docs are certainly the official ones (we don't want the
> specs to be written as header files in C). To me, the headers under
> xen/include/public/io/ are optional helpers. It doesn't matter what's in
> there, or if frontends and backends use them or not.
>
> There is really an argument for removing those headers, because they
> might get out of sync with the spec by mistake, and in those cases, then
> we really end up with two specifications for the same protocol. I would
> be in favor of `git rm'ing all files under xen/include/public/io/ for
> which we have a complete design doc under docs/misc.

+1.

Specifications should not be written in C.  The mess that is the net and
block protocol ABIs are perfect examples of why.

Its fine (and indeed recommended) to provide a header file which
describes the specified protocol, but the authoritative spec should be
in text from.

I would really prefer if more people started using ../docs/specs/.  The
migration v2 documents are currently lonely there...

~Andrew

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

[Stefano Stabellini]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 4668 bytes --]

On Thu, 22 Jun 2017, Andrew Cooper wrote:
> On 22/06/17 19:29, Stefano Stabellini wrote:
> > On Thu, 22 Jun 2017, Roger Pau Monné wrote:
> >> On Wed, Jun 21, 2017 at 01:16:56PM -0700, Stefano Stabellini wrote:
> >>> On Tue, 20 Jun 2017, Roger Pau Monné 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@aporeto.com>
> >>>>> CC: boris.ostrovsky@oracle.com
> >>>>> CC: jgross@suse.com
> >>>>> ---
> >>>>>  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.
> >> Oh I see. I still think this should be part of the public pvcalls.h
> >> header, and that the error codes should be the ones defined in
> >> public/errno.h (or else also added to the pvcalls header).
> > This was done differently in the past, but now that we have a formal
> > process, a person in charge of new PV drivers reviews, and design
> > documents with clearly spelled out ABIs, I consider the design docs
> > under docs/misc as the official specification. We don't need headers
> > anymore, they are redundant. In fact, we cannot have two specifications,
> > and the design docs are certainly the official ones (we don't want the
> > specs to be written as header files in C). To me, the headers under
> > xen/include/public/io/ are optional helpers. It doesn't matter what's in
> > there, or if frontends and backends use them or not.
> >
> > There is really an argument for removing those headers, because they
> > might get out of sync with the spec by mistake, and in those cases, then
> > we really end up with two specifications for the same protocol. I would
> > be in favor of `git rm'ing all files under xen/include/public/io/ for
> > which we have a complete design doc under docs/misc.
> 
> +1.
> 
> Specifications should not be written in C.  The mess that is the net and
> block protocol ABIs are perfect examples of why.
> 
> Its fine (and indeed recommended) to provide a header file which
> describes the specified protocol, but the authoritative spec should be
> in text from.
> 
> I would really prefer if more people started using ../docs/specs/.  The
> migration v2 documents are currently lonely there...

I didn't realize we had a docs/specs. Feel free to move pvcalls and 9pfs
under there.

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

[Roger Pau Monné]

On Thu, Jun 22, 2017 at 11:29:44AM -0700, Stefano Stabellini wrote:
> On Thu, 22 Jun 2017, Roger Pau Monné wrote:
> > On Wed, Jun 21, 2017 at 01:16:56PM -0700, Stefano Stabellini wrote:
> > > On Tue, 20 Jun 2017, Roger Pau Monné 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@aporeto.com>
> > > > > CC: boris.ostrovsky@oracle.com
> > > > > CC: jgross@suse.com
> > > > > ---
> > > > >  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.
> > 
> > Oh I see. I still think this should be part of the public pvcalls.h
> > header, and that the error codes should be the ones defined in
> > public/errno.h (or else also added to the pvcalls header).
> 
> This was done differently in the past, but now that we have a formal
> process, a person in charge of new PV drivers reviews, and design
> documents with clearly spelled out ABIs, I consider the design docs
> under docs/misc as the official specification. We don't need headers
> anymore, they are redundant. In fact, we cannot have two specifications,
> and the design docs are certainly the official ones (we don't want the
> specs to be written as header files in C). To me, the headers under
> xen/include/public/io/ are optional helpers. It doesn't matter what's in
> there, or if frontends and backends use them or not.
> 
> There is really an argument for removing those headers, because they
> might get out of sync with the spec by mistake, and in those cases, then
> we really end up with two specifications for the same protocol. I would
> be in favor of `git rm'ing all files under xen/include/public/io/ for
> which we have a complete design doc under docs/misc.

Thanks for the clarification. I agree that it would be good to remove
those headers, it's confusing and it's likely that they will get out
of sync.

Roger.

[PATCH v4 08/18] xen/pvcalls: implement connect command

[Stefano Stabellini]

Allocate a socket. Keep track of socket <-> ring mappings with a new data
structure, called sock_mapping. Implement the connect command by calling
inet_stream_connect, and mapping the new indexes page and data ring.
Allocate a workqueue and a work_struct, called ioworker, to perform
reads and writes to the socket.

When an active socket is closed (sk_state_change), set in_error to
-ENOTCONN and notify the other end, as specified by the protocol.

sk_data_ready and pvcalls_back_ioworker will be implemented later.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 171 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 171 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 953458b..4eecd83 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -56,6 +56,39 @@ struct pvcalls_fedata {
 	struct work_struct register_work;
 };
 
+struct pvcalls_ioworker {
+	struct work_struct register_work;
+	struct workqueue_struct *wq;
+};
+
+struct sock_mapping {
+	struct list_head list;
+	struct pvcalls_fedata *fedata;
+	struct socket *sock;
+	uint64_t id;
+	grant_ref_t ref;
+	struct pvcalls_data_intf *ring;
+	void *bytes;
+	struct pvcalls_data data;
+	uint32_t ring_order;
+	int irq;
+	atomic_t read;
+	atomic_t write;
+	atomic_t io;
+	atomic_t release;
+	void (*saved_data_ready)(struct sock *sk);
+	struct pvcalls_ioworker ioworker;
+};
+
+static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map);
+static int pvcalls_back_release_active(struct xenbus_device *dev,
+				       struct pvcalls_fedata *fedata,
+				       struct sock_mapping *map);
+
+static void pvcalls_back_ioworker(struct work_struct *work)
+{
+}
+
 static int pvcalls_back_socket(struct xenbus_device *dev,
 		struct xen_pvcalls_request *req)
 {
@@ -84,9 +117,142 @@ static int pvcalls_back_socket(struct xenbus_device *dev,
 	return 0;
 }
 
+static void pvcalls_sk_state_change(struct sock *sock)
+{
+	struct sock_mapping *map = sock->sk_user_data;
+	struct pvcalls_data_intf *intf;
+
+	if (map == NULL)
+		return;
+
+	intf = map->ring;
+	intf->in_error = -ENOTCONN;
+	notify_remote_via_irq(map->irq);
+}
+
+static void pvcalls_sk_data_ready(struct sock *sock)
+{
+}
+
+static struct sock_mapping *pvcalls_new_active_socket(
+		struct pvcalls_fedata *fedata,
+		uint64_t id,
+		grant_ref_t ref,
+		uint32_t evtchn,
+		struct socket *sock)
+{
+	int ret;
+	struct sock_mapping *map;
+	void *page;
+
+	map = kzalloc(sizeof(*map), GFP_KERNEL);
+	if (map == NULL)
+		return NULL;
+
+	map->fedata = fedata;
+	map->sock = sock;
+	map->id = id;
+	map->ref = ref;
+
+	ret = xenbus_map_ring_valloc(fedata->dev, &ref, 1, &page);
+	if (ret < 0)
+		goto out;
+	map->ring = page;
+	map->ring_order = map->ring->ring_order;
+	/* first read the order, then map the data ring */
+	virt_rmb();
+	if (map->ring_order > MAX_RING_ORDER) {
+		pr_warn("%s frontend requested ring_order %u, which is > MAX (%u)\n",
+				__func__, map->ring_order, MAX_RING_ORDER);
+		goto out;
+	}
+	ret = xenbus_map_ring_valloc(fedata->dev, map->ring->ref,
+				     (1 << map->ring_order), &page);
+	if (ret < 0)
+		goto out;
+	map->bytes = page;
+
+	ret = bind_interdomain_evtchn_to_irqhandler(fedata->dev->otherend_id,
+						    evtchn,
+						    pvcalls_back_conn_event,
+						    0,
+						    "pvcalls-backend",
+						    map);
+	if (ret < 0)
+		goto out;
+	map->irq = ret;
+
+	map->data.in = map->bytes;
+	map->data.out = map->bytes + XEN_FLEX_RING_SIZE(map->ring_order);
+	
+	map->ioworker.wq = alloc_workqueue("pvcalls_io", WQ_UNBOUND, 1);
+	if (!map->ioworker.wq)
+		goto out;
+	atomic_set(&map->io, 1);
+	INIT_WORK(&map->ioworker.register_work,	pvcalls_back_ioworker);
+
+	down(&fedata->socket_lock);
+	list_add_tail(&map->list, &fedata->socket_mappings);
+	up(&fedata->socket_lock);
+
+	write_lock_bh(&map->sock->sk->sk_callback_lock);
+	map->saved_data_ready = map->sock->sk->sk_data_ready;
+	map->sock->sk->sk_user_data = map;
+	map->sock->sk->sk_data_ready = pvcalls_sk_data_ready;
+	map->sock->sk->sk_state_change = pvcalls_sk_state_change;
+	write_unlock_bh(&map->sock->sk->sk_callback_lock);
+
+	return map;
+out:
+	pvcalls_back_release_active(fedata->dev, fedata, map);
+	return NULL;
+}
+
 static int pvcalls_back_connect(struct xenbus_device *dev,
 				struct xen_pvcalls_request *req)
 {
+	struct pvcalls_fedata *fedata;
+	int ret = -EINVAL;
+	struct socket *sock;
+	struct sock_mapping *map;
+	struct xen_pvcalls_response *rsp;
+
+	fedata = dev_get_drvdata(&dev->dev);
+
+	ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
+	if (ret < 0)
+		goto out;
+	ret = inet_stream_connect(sock, (struct sockaddr *)&req->u.connect.addr,
+				  req->u.connect.len, req->u.connect.flags);
+	if (ret < 0) {
+		sock_release(sock);
+		goto out;
+	}
+	
+	map = pvcalls_new_active_socket(fedata,
+					req->u.connect.id,
+					req->u.connect.ref,
+					req->u.connect.evtchn,
+					sock);
+	if (!map) {
+		sock_release(map->sock);
+		goto out;
+	}
+
+out:
+	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
+	rsp->req_id = req->req_id;
+	rsp->cmd = req->cmd;
+	rsp->u.connect.id = req->u.connect.id;
+	rsp->ret = ret;
+
+	return ret;
+}
+
+static int pvcalls_back_release_active(struct xenbus_device *dev,
+				       struct pvcalls_fedata *fedata,
+				       struct sock_mapping *map)
+{
 	return 0;
 }
 
@@ -206,6 +372,11 @@ static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
+{
+	return IRQ_HANDLED;
+}
+
 static int backend_connect(struct xenbus_device *dev)
 {
 	int err, evtchn;
-- 
1.9.1

Re: [PATCH v4 08/18] xen/pvcalls: implement connect command

[Boris Ostrovsky]

On 06/15/2017 03:09 PM, Stefano Stabellini wrote:
> Allocate a socket. Keep track of socket <-> ring mappings with a new data
> structure, called sock_mapping. Implement the connect command by calling
> inet_stream_connect, and mapping the new indexes page and data ring.
> Allocate a workqueue and a work_struct, called ioworker, to perform
> reads and writes to the socket.
>
> When an active socket is closed (sk_state_change), set in_error to
> -ENOTCONN and notify the other end, as specified by the protocol.
>
> sk_data_ready and pvcalls_back_ioworker will be implemented later.
>
> Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
> CC: boris.ostrovsky@oracle.com
> CC: jgross@suse.com
> ---
>  drivers/xen/pvcalls-back.c | 171 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 171 insertions(+)
>
> diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> index 953458b..4eecd83 100644
> --- a/drivers/xen/pvcalls-back.c
> +++ b/drivers/xen/pvcalls-back.c
> @@ -56,6 +56,39 @@ struct pvcalls_fedata {
>  	struct work_struct register_work;
>  };
>  
> +struct pvcalls_ioworker {
> +	struct work_struct register_work;
> +	struct workqueue_struct *wq;
> +};
> +
> +struct sock_mapping {
> +	struct list_head list;
> +	struct pvcalls_fedata *fedata;
> +	struct socket *sock;
> +	uint64_t id;
> +	grant_ref_t ref;
> +	struct pvcalls_data_intf *ring;
> +	void *bytes;
> +	struct pvcalls_data data;
> +	uint32_t ring_order;
> +	int irq;
> +	atomic_t read;
> +	atomic_t write;
> +	atomic_t io;
> +	atomic_t release;
> +	void (*saved_data_ready)(struct sock *sk);
> +	struct pvcalls_ioworker ioworker;
> +};
> +
> +static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map);
> +static int pvcalls_back_release_active(struct xenbus_device *dev,
> +				       struct pvcalls_fedata *fedata,
> +				       struct sock_mapping *map);
> +
> +static void pvcalls_back_ioworker(struct work_struct *work)
> +{
> +}
> +
>  static int pvcalls_back_socket(struct xenbus_device *dev,
>  		struct xen_pvcalls_request *req)
>  {
> @@ -84,9 +117,142 @@ static int pvcalls_back_socket(struct xenbus_device *dev,
>  	return 0;
>  }
>  
> +static void pvcalls_sk_state_change(struct sock *sock)
> +{
> +	struct sock_mapping *map = sock->sk_user_data;
> +	struct pvcalls_data_intf *intf;
> +
> +	if (map == NULL)
> +		return;
> +
> +	intf = map->ring;
> +	intf->in_error = -ENOTCONN;
> +	notify_remote_via_irq(map->irq);
> +}
> +
> +static void pvcalls_sk_data_ready(struct sock *sock)
> +{
> +}
> +
> +static struct sock_mapping *pvcalls_new_active_socket(
> +		struct pvcalls_fedata *fedata,
> +		uint64_t id,
> +		grant_ref_t ref,
> +		uint32_t evtchn,
> +		struct socket *sock)
> +{
> +	int ret;
> +	struct sock_mapping *map;
> +	void *page;
> +
> +	map = kzalloc(sizeof(*map), GFP_KERNEL);
> +	if (map == NULL)
> +		return NULL;
> +
> +	map->fedata = fedata;
> +	map->sock = sock;
> +	map->id = id;
> +	map->ref = ref;
> +
> +	ret = xenbus_map_ring_valloc(fedata->dev, &ref, 1, &page);
> +	if (ret < 0)
> +		goto out;
> +	map->ring = page;
> +	map->ring_order = map->ring->ring_order;
> +	/* first read the order, then map the data ring */
> +	virt_rmb();
> +	if (map->ring_order > MAX_RING_ORDER) {
> +		pr_warn("%s frontend requested ring_order %u, which is > MAX (%u)\n",
> +				__func__, map->ring_order, MAX_RING_ORDER);
> +		goto out;
> +	}
> +	ret = xenbus_map_ring_valloc(fedata->dev, map->ring->ref,
> +				     (1 << map->ring_order), &page);
> +	if (ret < 0)
> +		goto out;
> +	map->bytes = page;
> +
> +	ret = bind_interdomain_evtchn_to_irqhandler(fedata->dev->otherend_id,
> +						    evtchn,
> +						    pvcalls_back_conn_event,
> +						    0,
> +						    "pvcalls-backend",
> +						    map);
> +	if (ret < 0)
> +		goto out;
> +	map->irq = ret;
> +
> +	map->data.in = map->bytes;
> +	map->data.out = map->bytes + XEN_FLEX_RING_SIZE(map->ring_order);
> +	
> +	map->ioworker.wq = alloc_workqueue("pvcalls_io", WQ_UNBOUND, 1);
> +	if (!map->ioworker.wq)
> +		goto out;
> +	atomic_set(&map->io, 1);
> +	INIT_WORK(&map->ioworker.register_work,	pvcalls_back_ioworker);
> +
> +	down(&fedata->socket_lock);
> +	list_add_tail(&map->list, &fedata->socket_mappings);
> +	up(&fedata->socket_lock);
> +
> +	write_lock_bh(&map->sock->sk->sk_callback_lock);
> +	map->saved_data_ready = map->sock->sk->sk_data_ready;
> +	map->sock->sk->sk_user_data = map;
> +	map->sock->sk->sk_data_ready = pvcalls_sk_data_ready;
> +	map->sock->sk->sk_state_change = pvcalls_sk_state_change;
> +	write_unlock_bh(&map->sock->sk->sk_callback_lock);
> +
> +	return map;
> +out:
> +	pvcalls_back_release_active(fedata->dev, fedata, map);

cleanup? (Unless it is supposed to happen in
pvcalls_back_release_active(), which it is not at this patch level)

> +	return NULL;
> +}
> +
>  static int pvcalls_back_connect(struct xenbus_device *dev,
>  				struct xen_pvcalls_request *req)
>  {
> +	struct pvcalls_fedata *fedata;
> +	int ret = -EINVAL;
> +	struct socket *sock;
> +	struct sock_mapping *map;
> +	struct xen_pvcalls_response *rsp;
> +
> +	fedata = dev_get_drvdata(&dev->dev);
> +
> +	ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
> +	if (ret < 0)
> +		goto out;
> +	ret = inet_stream_connect(sock, (struct sockaddr *)&req->u.connect.addr,
> +				  req->u.connect.len, req->u.connect.flags);
> +	if (ret < 0) {
> +		sock_release(sock);
> +		goto out;
> +	}
> +	
> +	map = pvcalls_new_active_socket(fedata,
> +					req->u.connect.id,
> +					req->u.connect.ref,
> +					req->u.connect.evtchn,
> +					sock);
> +	if (!map) {
> +		sock_release(map->sock);
> +		goto out;

Unnecessary goto.

> +	}
> +
> +out:
> +	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
> +	rsp->req_id = req->req_id;
> +	rsp->cmd = req->cmd;
> +	rsp->u.connect.id = req->u.connect.id;
> +	rsp->ret = ret;
> +
> +	return ret;

Just like in other handlers, return 0?

-boris


> +}
> +
> +static int pvcalls_back_release_active(struct xenbus_device *dev,
> +				       struct pvcalls_fedata *fedata,
> +				       struct sock_mapping *map)
> +{
>  	return 0;
>  }
>  
> @@ -206,6 +372,11 @@ static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> +static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
> +{
> +	return IRQ_HANDLED;
> +}
> +
>  static int backend_connect(struct xenbus_device *dev)
>  {
>  	int err, evtchn;

Re: [PATCH v4 08/18] xen/pvcalls: implement connect command

[Boris Ostrovsky]

>> +
>>  static int pvcalls_back_connect(struct xenbus_device *dev,
>>  				struct xen_pvcalls_request *req)
>>  {
>> +	struct pvcalls_fedata *fedata;
>> +	int ret = -EINVAL;
>> +	struct socket *sock;
>> +	struct sock_mapping *map;
>> +	struct xen_pvcalls_response *rsp;
>> +
>> +	fedata = dev_get_drvdata(&dev->dev);
>> +
>> +	ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
>> +	if (ret < 0)
>> +		goto out;
>> +	ret = inet_stream_connect(sock, (struct sockaddr *)&req->u.connect.addr,
>> +				  req->u.connect.len, req->u.connect.flags);
>> +	if (ret < 0) {
>> +		sock_release(sock);
>> +		goto out;
>> +	}
>> +	
>> +	map = pvcalls_new_active_socket(fedata,
>> +					req->u.connect.id,
>> +					req->u.connect.ref,
>> +					req->u.connect.evtchn,
>> +					sock);
>> +	if (!map) {
>> +		sock_release(map->sock);
>> +		goto out;
> Unnecessary goto.

Oh, and also ret needs to be set since it will be cleared by
inet_stream_connect().

-boris


>
>> +	}
>> +
>> +out:
>> +	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
>> +	rsp->req_id = req->req_id;
>> +	rsp->cmd = req->cmd;
>> +	rsp->u.connect.id = req->u.connect.id;
>> +	rsp->ret = ret;
>> +
>> +	return ret;
>

Re: [PATCH v4 08/18] xen/pvcalls: implement connect command

[Stefano Stabellini]

On Tue, 20 Jun 2017, Boris Ostrovsky wrote:
> >> +
> >>  static int pvcalls_back_connect(struct xenbus_device *dev,
> >>  				struct xen_pvcalls_request *req)
> >>  {
> >> +	struct pvcalls_fedata *fedata;
> >> +	int ret = -EINVAL;
> >> +	struct socket *sock;
> >> +	struct sock_mapping *map;
> >> +	struct xen_pvcalls_response *rsp;
> >> +
> >> +	fedata = dev_get_drvdata(&dev->dev);
> >> +
> >> +	ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
> >> +	if (ret < 0)
> >> +		goto out;
> >> +	ret = inet_stream_connect(sock, (struct sockaddr *)&req->u.connect.addr,
> >> +				  req->u.connect.len, req->u.connect.flags);
> >> +	if (ret < 0) {
> >> +		sock_release(sock);
> >> +		goto out;
> >> +	}
> >> +	
> >> +	map = pvcalls_new_active_socket(fedata,
> >> +					req->u.connect.id,
> >> +					req->u.connect.ref,
> >> +					req->u.connect.evtchn,
> >> +					sock);
> >> +	if (!map) {
> >> +		sock_release(map->sock);
> >> +		goto out;
> > Unnecessary goto.
> 
> Oh, and also ret needs to be set since it will be cleared by
> inet_stream_connect().

Right, thanks!

> >
> >> +	}
> >> +
> >> +out:
> >> +	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
> >> +	rsp->req_id = req->req_id;
> >> +	rsp->cmd = req->cmd;
> >> +	rsp->u.connect.id = req->u.connect.id;
> >> +	rsp->ret = ret;
> >> +
> >> +	return ret;
> >
> 

Re: [PATCH v4 08/18] xen/pvcalls: implement connect command

[Stefano Stabellini]

On Tue, 20 Jun 2017, Boris Ostrovsky wrote:
> On 06/15/2017 03:09 PM, Stefano Stabellini wrote:
> > Allocate a socket. Keep track of socket <-> ring mappings with a new data
> > structure, called sock_mapping. Implement the connect command by calling
> > inet_stream_connect, and mapping the new indexes page and data ring.
> > Allocate a workqueue and a work_struct, called ioworker, to perform
> > reads and writes to the socket.
> >
> > When an active socket is closed (sk_state_change), set in_error to
> > -ENOTCONN and notify the other end, as specified by the protocol.
> >
> > sk_data_ready and pvcalls_back_ioworker will be implemented later.
> >
> > Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
> > CC: boris.ostrovsky@oracle.com
> > CC: jgross@suse.com
> > ---
> >  drivers/xen/pvcalls-back.c | 171 +++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 171 insertions(+)
> >
> > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> > index 953458b..4eecd83 100644
> > --- a/drivers/xen/pvcalls-back.c
> > +++ b/drivers/xen/pvcalls-back.c
> > @@ -56,6 +56,39 @@ struct pvcalls_fedata {
> >  	struct work_struct register_work;
> >  };
> >  
> > +struct pvcalls_ioworker {
> > +	struct work_struct register_work;
> > +	struct workqueue_struct *wq;
> > +};
> > +
> > +struct sock_mapping {
> > +	struct list_head list;
> > +	struct pvcalls_fedata *fedata;
> > +	struct socket *sock;
> > +	uint64_t id;
> > +	grant_ref_t ref;
> > +	struct pvcalls_data_intf *ring;
> > +	void *bytes;
> > +	struct pvcalls_data data;
> > +	uint32_t ring_order;
> > +	int irq;
> > +	atomic_t read;
> > +	atomic_t write;
> > +	atomic_t io;
> > +	atomic_t release;
> > +	void (*saved_data_ready)(struct sock *sk);
> > +	struct pvcalls_ioworker ioworker;
> > +};
> > +
> > +static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map);
> > +static int pvcalls_back_release_active(struct xenbus_device *dev,
> > +				       struct pvcalls_fedata *fedata,
> > +				       struct sock_mapping *map);
> > +
> > +static void pvcalls_back_ioworker(struct work_struct *work)
> > +{
> > +}
> > +
> >  static int pvcalls_back_socket(struct xenbus_device *dev,
> >  		struct xen_pvcalls_request *req)
> >  {
> > @@ -84,9 +117,142 @@ static int pvcalls_back_socket(struct xenbus_device *dev,
> >  	return 0;
> >  }
> >  
> > +static void pvcalls_sk_state_change(struct sock *sock)
> > +{
> > +	struct sock_mapping *map = sock->sk_user_data;
> > +	struct pvcalls_data_intf *intf;
> > +
> > +	if (map == NULL)
> > +		return;
> > +
> > +	intf = map->ring;
> > +	intf->in_error = -ENOTCONN;
> > +	notify_remote_via_irq(map->irq);
> > +}
> > +
> > +static void pvcalls_sk_data_ready(struct sock *sock)
> > +{
> > +}
> > +
> > +static struct sock_mapping *pvcalls_new_active_socket(
> > +		struct pvcalls_fedata *fedata,
> > +		uint64_t id,
> > +		grant_ref_t ref,
> > +		uint32_t evtchn,
> > +		struct socket *sock)
> > +{
> > +	int ret;
> > +	struct sock_mapping *map;
> > +	void *page;
> > +
> > +	map = kzalloc(sizeof(*map), GFP_KERNEL);
> > +	if (map == NULL)
> > +		return NULL;
> > +
> > +	map->fedata = fedata;
> > +	map->sock = sock;
> > +	map->id = id;
> > +	map->ref = ref;
> > +
> > +	ret = xenbus_map_ring_valloc(fedata->dev, &ref, 1, &page);
> > +	if (ret < 0)
> > +		goto out;
> > +	map->ring = page;
> > +	map->ring_order = map->ring->ring_order;
> > +	/* first read the order, then map the data ring */
> > +	virt_rmb();
> > +	if (map->ring_order > MAX_RING_ORDER) {
> > +		pr_warn("%s frontend requested ring_order %u, which is > MAX (%u)\n",
> > +				__func__, map->ring_order, MAX_RING_ORDER);
> > +		goto out;
> > +	}
> > +	ret = xenbus_map_ring_valloc(fedata->dev, map->ring->ref,
> > +				     (1 << map->ring_order), &page);
> > +	if (ret < 0)
> > +		goto out;
> > +	map->bytes = page;
> > +
> > +	ret = bind_interdomain_evtchn_to_irqhandler(fedata->dev->otherend_id,
> > +						    evtchn,
> > +						    pvcalls_back_conn_event,
> > +						    0,
> > +						    "pvcalls-backend",
> > +						    map);
> > +	if (ret < 0)
> > +		goto out;
> > +	map->irq = ret;
> > +
> > +	map->data.in = map->bytes;
> > +	map->data.out = map->bytes + XEN_FLEX_RING_SIZE(map->ring_order);
> > +	
> > +	map->ioworker.wq = alloc_workqueue("pvcalls_io", WQ_UNBOUND, 1);
> > +	if (!map->ioworker.wq)
> > +		goto out;
> > +	atomic_set(&map->io, 1);
> > +	INIT_WORK(&map->ioworker.register_work,	pvcalls_back_ioworker);
> > +
> > +	down(&fedata->socket_lock);
> > +	list_add_tail(&map->list, &fedata->socket_mappings);
> > +	up(&fedata->socket_lock);
> > +
> > +	write_lock_bh(&map->sock->sk->sk_callback_lock);
> > +	map->saved_data_ready = map->sock->sk->sk_data_ready;
> > +	map->sock->sk->sk_user_data = map;
> > +	map->sock->sk->sk_data_ready = pvcalls_sk_data_ready;
> > +	map->sock->sk->sk_state_change = pvcalls_sk_state_change;
> > +	write_unlock_bh(&map->sock->sk->sk_callback_lock);
> > +
> > +	return map;
> > +out:
> > +	pvcalls_back_release_active(fedata->dev, fedata, map);
> 
> cleanup? (Unless it is supposed to happen in
> pvcalls_back_release_active(), which it is not at this patch level)

Yes, pvcalls_back_release_active takes care of the cleanup, it's
implemented in patch #13


> > +	return NULL;
> > +}
> > +
> >  static int pvcalls_back_connect(struct xenbus_device *dev,
> >  				struct xen_pvcalls_request *req)
> >  {
> > +	struct pvcalls_fedata *fedata;
> > +	int ret = -EINVAL;
> > +	struct socket *sock;
> > +	struct sock_mapping *map;
> > +	struct xen_pvcalls_response *rsp;
> > +
> > +	fedata = dev_get_drvdata(&dev->dev);
> > +
> > +	ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
> > +	if (ret < 0)
> > +		goto out;
> > +	ret = inet_stream_connect(sock, (struct sockaddr *)&req->u.connect.addr,
> > +				  req->u.connect.len, req->u.connect.flags);
> > +	if (ret < 0) {
> > +		sock_release(sock);
> > +		goto out;
> > +	}
> > +	
> > +	map = pvcalls_new_active_socket(fedata,
> > +					req->u.connect.id,
> > +					req->u.connect.ref,
> > +					req->u.connect.evtchn,
> > +					sock);
> > +	if (!map) {
> > +		sock_release(map->sock);
> > +		goto out;
> 
> Unnecessary goto.

I'll fix


> > +	}
> > +
> > +out:
> > +	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
> > +	rsp->req_id = req->req_id;
> > +	rsp->cmd = req->cmd;
> > +	rsp->u.connect.id = req->u.connect.id;
> > +	rsp->ret = ret;
> > +
> > +	return ret;
> 
> Just like in other handlers, return 0?

Yes, I'll do that


> > +}
> > +
> > +static int pvcalls_back_release_active(struct xenbus_device *dev,
> > +				       struct pvcalls_fedata *fedata,
> > +				       struct sock_mapping *map)
> > +{
> >  	return 0;
> >  }
> >  
> > @@ -206,6 +372,11 @@ static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
> >  	return IRQ_HANDLED;
> >  }
> >  
> > +static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
> > +{
> > +	return IRQ_HANDLED;
> > +}
> > +
> >  static int backend_connect(struct xenbus_device *dev)
> >  {
> >  	int err, evtchn;
> 

[PATCH v4 09/18] xen/pvcalls: implement bind command

[Stefano Stabellini]

Allocate a socket. Track the allocated passive sockets with a new data
structure named sockpass_mapping. It contains an unbound workqueue to
schedule delayed work for the accept and poll commands. It also has a
reqcopy field to be used to store a copy of a request for delayed work.
Reads/writes to it are protected by a lock (the "copy_lock" spinlock).
Initialize the workqueue in pvcalls_back_bind.

Implement the bind command with inet_bind.

The pass_sk_data_ready event handler will be added later.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 4eecd83..c17d970 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -80,6 +80,18 @@ struct sock_mapping {
 	struct pvcalls_ioworker ioworker;
 };
 
+struct sockpass_mapping {
+	struct list_head list;
+	struct pvcalls_fedata *fedata;
+	struct socket *sock;
+	uint64_t id;
+	struct xen_pvcalls_request reqcopy;
+	spinlock_t copy_lock;
+	struct workqueue_struct *wq;
+	struct work_struct register_work;
+	void (*saved_data_ready)(struct sock *sk);
+};
+
 static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map);
 static int pvcalls_back_release_active(struct xenbus_device *dev,
 				       struct pvcalls_fedata *fedata,
@@ -262,9 +274,84 @@ static int pvcalls_back_release(struct xenbus_device *dev,
 	return 0;
 }
 
+static void __pvcalls_back_accept(struct work_struct *work)
+{
+}
+
+static void pvcalls_pass_sk_data_ready(struct sock *sock)
+{
+}
+
 static int pvcalls_back_bind(struct xenbus_device *dev,
 			     struct xen_pvcalls_request *req)
 {
+	struct pvcalls_fedata *fedata;
+	int ret, err;
+	struct socket *sock;
+	struct sockpass_mapping *map;
+	struct xen_pvcalls_response *rsp;
+
+	fedata = dev_get_drvdata(&dev->dev);
+
+	map = kzalloc(sizeof(*map), GFP_KERNEL);
+	if (map == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	INIT_WORK(&map->register_work, __pvcalls_back_accept);
+	spin_lock_init(&map->copy_lock);
+	map->wq = alloc_workqueue("pvcalls_wq", WQ_UNBOUND, 1);
+	if (!map->wq) {
+		ret = -ENOMEM;
+		kfree(map);
+		goto out;
+	}
+
+	ret = sock_create(AF_INET, SOCK_STREAM, 0, &sock);
+	if (ret < 0) {
+		destroy_workqueue(map->wq);
+		kfree(map);
+		goto out;
+	}
+
+	ret = inet_bind(sock, (struct sockaddr *)&req->u.bind.addr,
+			req->u.bind.len);
+	if (ret < 0) {
+		sock_release(sock);
+		destroy_workqueue(map->wq);
+		kfree(map);
+		goto out;
+	}
+
+	map->fedata = fedata;
+	map->sock = sock;
+	map->id = req->u.bind.id;
+
+	down(&fedata->socket_lock);
+	err = radix_tree_insert(&fedata->socketpass_mappings, map->id,
+				map);
+	up(&fedata->socket_lock);
+	if (err) {
+		ret = err;
+		sock_release(sock);
+		destroy_workqueue(map->wq);
+		kfree(map);
+		goto out;
+	}
+
+	write_lock_bh(&sock->sk->sk_callback_lock);
+	map->saved_data_ready = sock->sk->sk_data_ready;
+	sock->sk->sk_user_data = map;
+	sock->sk->sk_data_ready = pvcalls_pass_sk_data_ready;
+	write_unlock_bh(&sock->sk->sk_callback_lock);
+
+out:
+	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
+	rsp->req_id = req->req_id;
+	rsp->cmd = req->cmd;
+	rsp->u.bind.id = req->u.bind.id;
+	rsp->ret = ret;
 	return 0;
 }
 
-- 
1.9.1

[PATCH v4 10/18] xen/pvcalls: implement listen command

[Stefano Stabellini]

Call inet_listen to implement the listen command.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index c17d970..e5c535d 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -358,6 +358,25 @@ static int pvcalls_back_bind(struct xenbus_device *dev,
 static int pvcalls_back_listen(struct xenbus_device *dev,
 			       struct xen_pvcalls_request *req)
 {
+	struct pvcalls_fedata *fedata;
+	int ret = -EINVAL;
+	struct sockpass_mapping *map;
+	struct xen_pvcalls_response *rsp;
+
+	fedata = dev_get_drvdata(&dev->dev);
+
+	map = radix_tree_lookup(&fedata->socketpass_mappings, req->u.listen.id);
+	if (map == NULL)
+		goto out;
+
+	ret = inet_listen(map->sock, req->u.listen.backlog);
+
+out:
+	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
+	rsp->req_id = req->req_id;
+	rsp->cmd = req->cmd;
+	rsp->u.listen.id = req->u.listen.id;
+	rsp->ret = ret;
 	return 0;
 }
 
-- 
1.9.1

Re: [PATCH v4 10/18] xen/pvcalls: implement listen command

[Boris Ostrovsky]

On 06/15/2017 03:09 PM, Stefano Stabellini wrote:
> Call inet_listen to implement the listen command.
>
> Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
> CC: boris.ostrovsky@oracle.com
> CC: jgross@suse.com

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

> ---
>  drivers/xen/pvcalls-back.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> index c17d970..e5c535d 100644
> --- a/drivers/xen/pvcalls-back.c
> +++ b/drivers/xen/pvcalls-back.c
> @@ -358,6 +358,25 @@ static int pvcalls_back_bind(struct xenbus_device *dev,
>  static int pvcalls_back_listen(struct xenbus_device *dev,
>  			       struct xen_pvcalls_request *req)
>  {
> +	struct pvcalls_fedata *fedata;
> +	int ret = -EINVAL;
> +	struct sockpass_mapping *map;
> +	struct xen_pvcalls_response *rsp;
> +
> +	fedata = dev_get_drvdata(&dev->dev);
> +
> +	map = radix_tree_lookup(&fedata->socketpass_mappings, req->u.listen.id);
> +	if (map == NULL)
> +		goto out;
> +
> +	ret = inet_listen(map->sock, req->u.listen.backlog);
> +
> +out:
> +	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
> +	rsp->req_id = req->req_id;
> +	rsp->cmd = req->cmd;
> +	rsp->u.listen.id = req->u.listen.id;
> +	rsp->ret = ret;
>  	return 0;

newline before return would be useful (if you respin this)

>  }
>  

[PATCH v4 11/18] xen/pvcalls: implement accept command

[Stefano Stabellini]

Implement the accept command by calling inet_accept. To avoid blocking
in the kernel, call inet_accept(O_NONBLOCK) from a workqueue, which get
scheduled on sk_data_ready (for a passive socket, it means that there
are connections to accept).

Use the reqcopy field to store the request. Accept the new socket from
the delayed work function, create a new sock_mapping for it, map
the indexes page and data ring, and reply to the other end. Allocate an
ioworker for the socket.

Only support one outstanding blocking accept request for every socket at
any time.

Add a field to sock_mapping to remember the passive socket from which an
active socket was created.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 110 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index e5c535d..701f1fc 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -64,6 +64,7 @@ struct pvcalls_ioworker {
 struct sock_mapping {
 	struct list_head list;
 	struct pvcalls_fedata *fedata;
+	struct sockpass_mapping *sockpass;
 	struct socket *sock;
 	uint64_t id;
 	grant_ref_t ref;
@@ -276,10 +277,82 @@ static int pvcalls_back_release(struct xenbus_device *dev,
 
 static void __pvcalls_back_accept(struct work_struct *work)
 {
+	struct sockpass_mapping *mappass = container_of(
+		work, struct sockpass_mapping, register_work);
+	struct sock_mapping *map;
+	struct pvcalls_ioworker *iow;
+	struct pvcalls_fedata *fedata;
+	struct socket *sock;
+	struct xen_pvcalls_response *rsp;
+	struct xen_pvcalls_request *req;
+	int notify;
+	int ret = -EINVAL;
+	unsigned long flags;
+
+	fedata = mappass->fedata;
+	/*
+	 * __pvcalls_back_accept can race against pvcalls_back_accept.
+	 * We only need to check the value of "cmd" on read. It could be
+	 * done atomically, but to simplify the code on the write side, we
+	 * use a spinlock.
+	 */
+	spin_lock_irqsave(&mappass->copy_lock, flags);
+	req = &mappass->reqcopy;
+	if (req->cmd != PVCALLS_ACCEPT) {
+		spin_unlock_irqrestore(&mappass->copy_lock, flags);
+		return;
+	}
+	spin_unlock_irqrestore(&mappass->copy_lock, flags);
+
+	sock = sock_alloc();
+	if (sock == NULL)
+		goto out_error;
+	sock->type = mappass->sock->type;
+	sock->ops = mappass->sock->ops;
+
+	ret = inet_accept(mappass->sock, sock, O_NONBLOCK, true);
+	if (ret == -EAGAIN) {
+		sock_release(sock);
+		goto out_error;
+	}
+
+	map = pvcalls_new_active_socket(fedata,
+					req->u.accept.id_new,
+					req->u.accept.ref,
+					req->u.accept.evtchn,
+					sock);
+	if (!map) {
+		sock_release(sock);
+		goto out_error;
+	}
+
+	map->sockpass = mappass;
+	iow = &map->ioworker;
+	atomic_inc(&map->read);
+	atomic_inc(&map->io);
+	queue_work(iow->wq, &iow->register_work);
+
+out_error:
+	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
+	rsp->req_id = req->req_id;
+	rsp->cmd = req->cmd;
+	rsp->u.accept.id = req->u.accept.id;
+	rsp->ret = ret;
+	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
+	if (notify)
+		notify_remote_via_irq(fedata->irq);
+
+	mappass->reqcopy.cmd = 0;
 }
 
 static void pvcalls_pass_sk_data_ready(struct sock *sock)
 {
+	struct sockpass_mapping *mappass = sock->sk_user_data;
+
+	if (mappass == NULL)
+		return;
+
+	queue_work(mappass->wq, &mappass->register_work);
 }
 
 static int pvcalls_back_bind(struct xenbus_device *dev,
@@ -383,6 +456,43 @@ static int pvcalls_back_listen(struct xenbus_device *dev,
 static int pvcalls_back_accept(struct xenbus_device *dev,
 			       struct xen_pvcalls_request *req)
 {
+	struct pvcalls_fedata *fedata;
+	struct sockpass_mapping *mappass;
+	int ret = -EINVAL;
+	struct xen_pvcalls_response *rsp;
+	unsigned long flags;
+
+	fedata = dev_get_drvdata(&dev->dev);
+
+	mappass = radix_tree_lookup(&fedata->socketpass_mappings,
+		req->u.accept.id);
+	if (mappass == NULL)
+		goto out_error;
+
+	/* 
+	 * Limitation of the current implementation: only support one
+	 * concurrent accept or poll call on one socket.
+	 */
+	spin_lock_irqsave(&mappass->copy_lock, flags);
+	if (mappass->reqcopy.cmd != 0) {
+		spin_unlock_irqrestore(&mappass->copy_lock, flags);
+		ret = -EINTR;
+		goto out_error;
+	}
+
+	mappass->reqcopy = *req;
+	spin_unlock_irqrestore(&mappass->copy_lock, flags);
+	queue_work(mappass->wq, &mappass->register_work);
+
+	/* Tell the caller we don't need to send back a notification yet */
+	return -1;
+
+out_error:
+	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
+	rsp->req_id = req->req_id;
+	rsp->cmd = req->cmd;
+	rsp->u.accept.id = req->u.accept.id;
+	rsp->ret = ret;
 	return 0;
 }
 
-- 
1.9.1

Re: [PATCH v4 11/18] xen/pvcalls: implement accept command

[Boris Ostrovsky]

>  static void __pvcalls_back_accept(struct work_struct *work)
>  {
> +	struct sockpass_mapping *mappass = container_of(
> +		work, struct sockpass_mapping, register_work);
> +	struct sock_mapping *map;
> +	struct pvcalls_ioworker *iow;
> +	struct pvcalls_fedata *fedata;
> +	struct socket *sock;
> +	struct xen_pvcalls_response *rsp;
> +	struct xen_pvcalls_request *req;
> +	int notify;
> +	int ret = -EINVAL;
> +	unsigned long flags;
> +
> +	fedata = mappass->fedata;
> +	/*
> +	 * __pvcalls_back_accept can race against pvcalls_back_accept.
> +	 * We only need to check the value of "cmd" on read. It could be
> +	 * done atomically, but to simplify the code on the write side, we
> +	 * use a spinlock.
> +	 */
> +	spin_lock_irqsave(&mappass->copy_lock, flags);
> +	req = &mappass->reqcopy;
> +	if (req->cmd != PVCALLS_ACCEPT) {
> +		spin_unlock_irqrestore(&mappass->copy_lock, flags);
> +		return;
> +	}
> +	spin_unlock_irqrestore(&mappass->copy_lock, flags);
> +
> +	sock = sock_alloc();
> +	if (sock == NULL)
> +		goto out_error;
> +	sock->type = mappass->sock->type;
> +	sock->ops = mappass->sock->ops;
> +
> +	ret = inet_accept(mappass->sock, sock, O_NONBLOCK, true);
> +	if (ret == -EAGAIN) {
> +		sock_release(sock);
> +		goto out_error;
> +	}
> +
> +	map = pvcalls_new_active_socket(fedata,
> +					req->u.accept.id_new,
> +					req->u.accept.ref,
> +					req->u.accept.evtchn,
> +					sock);
> +	if (!map) {
> +		sock_release(sock);
> +		goto out_error;

Again, lost ret value.

> +	}
> +
> +	map->sockpass = mappass;
> +	iow = &map->ioworker;
> +	atomic_inc(&map->read);
> +	atomic_inc(&map->io);
> +	queue_work(iow->wq, &iow->register_work);
> +
> +out_error:
> +	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
> +	rsp->req_id = req->req_id;
> +	rsp->cmd = req->cmd;
> +	rsp->u.accept.id = req->u.accept.id;
> +	rsp->ret = ret;
> +	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
> +	if (notify)
> +		notify_remote_via_irq(fedata->irq);
> +
> +	mappass->reqcopy.cmd = 0;
>  }
>  
>  static void pvcalls_pass_sk_data_ready(struct sock *sock)
>  {
> +	struct sockpass_mapping *mappass = sock->sk_user_data;
> +
> +	if (mappass == NULL)
> +		return;
> +
> +	queue_work(mappass->wq, &mappass->register_work);
>  }
>  
>  static int pvcalls_back_bind(struct xenbus_device *dev,
> @@ -383,6 +456,43 @@ static int pvcalls_back_listen(struct xenbus_device *dev,
>  static int pvcalls_back_accept(struct xenbus_device *dev,
>  			       struct xen_pvcalls_request *req)
>  {
> +	struct pvcalls_fedata *fedata;
> +	struct sockpass_mapping *mappass;
> +	int ret = -EINVAL;

Unnecessary initialization.

-boris

> +	struct xen_pvcalls_response *rsp;
> +	unsigned long flags;
> +
> +	fedata = dev_get_drvdata(&dev->dev);
> +
> +	mappass = radix_tree_lookup(&fedata->socketpass_mappings,
> +		req->u.accept.id);
> +	if (mappass == NULL)
> +		goto out_error;
> +
> +	/* 
> +	 * Limitation of the current implementation: only support one
> +	 * concurrent accept or poll call on one socket.
> +	 */
> +	spin_lock_irqsave(&mappass->copy_lock, flags);
> +	if (mappass->reqcopy.cmd != 0) {
> +		spin_unlock_irqrestore(&mappass->copy_lock, flags);
> +		ret = -EINTR;
> +		goto out_error;
> +	}
> +
> +	mappass->reqcopy = *req;
> +	spin_unlock_irqrestore(&mappass->copy_lock, flags);
> +	queue_work(mappass->wq, &mappass->register_work);
> +
> +	/* Tell the caller we don't need to send back a notification yet */
> +	return -1;
> +
> +out_error:
> +	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
> +	rsp->req_id = req->req_id;
> +	rsp->cmd = req->cmd;
> +	rsp->u.accept.id = req->u.accept.id;
> +	rsp->ret = ret;
>  	return 0;
>  }
>  

Re: [PATCH v4 11/18] xen/pvcalls: implement accept command

[Stefano Stabellini]

On Tue, 20 Jun 2017, Boris Ostrovsky wrote:
> >  static void __pvcalls_back_accept(struct work_struct *work)
> >  {
> > +	struct sockpass_mapping *mappass = container_of(
> > +		work, struct sockpass_mapping, register_work);
> > +	struct sock_mapping *map;
> > +	struct pvcalls_ioworker *iow;
> > +	struct pvcalls_fedata *fedata;
> > +	struct socket *sock;
> > +	struct xen_pvcalls_response *rsp;
> > +	struct xen_pvcalls_request *req;
> > +	int notify;
> > +	int ret = -EINVAL;
> > +	unsigned long flags;
> > +
> > +	fedata = mappass->fedata;
> > +	/*
> > +	 * __pvcalls_back_accept can race against pvcalls_back_accept.
> > +	 * We only need to check the value of "cmd" on read. It could be
> > +	 * done atomically, but to simplify the code on the write side, we
> > +	 * use a spinlock.
> > +	 */
> > +	spin_lock_irqsave(&mappass->copy_lock, flags);
> > +	req = &mappass->reqcopy;
> > +	if (req->cmd != PVCALLS_ACCEPT) {
> > +		spin_unlock_irqrestore(&mappass->copy_lock, flags);
> > +		return;
> > +	}
> > +	spin_unlock_irqrestore(&mappass->copy_lock, flags);
> > +
> > +	sock = sock_alloc();
> > +	if (sock == NULL)
> > +		goto out_error;
> > +	sock->type = mappass->sock->type;
> > +	sock->ops = mappass->sock->ops;
> > +
> > +	ret = inet_accept(mappass->sock, sock, O_NONBLOCK, true);
> > +	if (ret == -EAGAIN) {
> > +		sock_release(sock);
> > +		goto out_error;
> > +	}
> > +
> > +	map = pvcalls_new_active_socket(fedata,
> > +					req->u.accept.id_new,
> > +					req->u.accept.ref,
> > +					req->u.accept.evtchn,
> > +					sock);
> > +	if (!map) {
> > +		sock_release(sock);
> > +		goto out_error;
> 
> Again, lost ret value.

Yep, I'll fix


> > +	}
> > +
> > +	map->sockpass = mappass;
> > +	iow = &map->ioworker;
> > +	atomic_inc(&map->read);
> > +	atomic_inc(&map->io);
> > +	queue_work(iow->wq, &iow->register_work);
> > +
> > +out_error:
> > +	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
> > +	rsp->req_id = req->req_id;
> > +	rsp->cmd = req->cmd;
> > +	rsp->u.accept.id = req->u.accept.id;
> > +	rsp->ret = ret;
> > +	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
> > +	if (notify)
> > +		notify_remote_via_irq(fedata->irq);
> > +
> > +	mappass->reqcopy.cmd = 0;
> >  }
> >  
> >  static void pvcalls_pass_sk_data_ready(struct sock *sock)
> >  {
> > +	struct sockpass_mapping *mappass = sock->sk_user_data;
> > +
> > +	if (mappass == NULL)
> > +		return;
> > +
> > +	queue_work(mappass->wq, &mappass->register_work);
> >  }
> >  
> >  static int pvcalls_back_bind(struct xenbus_device *dev,
> > @@ -383,6 +456,43 @@ static int pvcalls_back_listen(struct xenbus_device *dev,
> >  static int pvcalls_back_accept(struct xenbus_device *dev,
> >  			       struct xen_pvcalls_request *req)
> >  {
> > +	struct pvcalls_fedata *fedata;
> > +	struct sockpass_mapping *mappass;
> > +	int ret = -EINVAL;
> 
> Unnecessary initialization.

It is not unnecessary: if mappass is NULL few lines below, it will goto
out_error without setting ret.


> > +	struct xen_pvcalls_response *rsp;
> > +	unsigned long flags;
> > +
> > +	fedata = dev_get_drvdata(&dev->dev);
> > +
> > +	mappass = radix_tree_lookup(&fedata->socketpass_mappings,
> > +		req->u.accept.id);
> > +	if (mappass == NULL)
> > +		goto out_error;
> > +
> > +	/* 
> > +	 * Limitation of the current implementation: only support one
> > +	 * concurrent accept or poll call on one socket.
> > +	 */
> > +	spin_lock_irqsave(&mappass->copy_lock, flags);
> > +	if (mappass->reqcopy.cmd != 0) {
> > +		spin_unlock_irqrestore(&mappass->copy_lock, flags);
> > +		ret = -EINTR;
> > +		goto out_error;
> > +	}
> > +
> > +	mappass->reqcopy = *req;
> > +	spin_unlock_irqrestore(&mappass->copy_lock, flags);
> > +	queue_work(mappass->wq, &mappass->register_work);
> > +
> > +	/* Tell the caller we don't need to send back a notification yet */
> > +	return -1;
> > +
> > +out_error:
> > +	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
> > +	rsp->req_id = req->req_id;
> > +	rsp->cmd = req->cmd;
> > +	rsp->u.accept.id = req->u.accept.id;
> > +	rsp->ret = ret;
> >  	return 0;
> >  }
> >  
> 

[PATCH v4 12/18] xen/pvcalls: implement poll command

[Stefano Stabellini]

Implement poll on passive sockets by requesting a delayed response with
mappass->reqcopy, and reply back when there is data on the passive
socket.

Poll on active socket is unimplemented as by the spec, as the frontend
should just wait for events and check the indexes on the indexes page.

Only support one outstanding poll (or accept) request for every passive
socket at any given time.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 73 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 701f1fc..be85977 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -348,11 +348,33 @@ static void __pvcalls_back_accept(struct work_struct *work)
 static void pvcalls_pass_sk_data_ready(struct sock *sock)
 {
 	struct sockpass_mapping *mappass = sock->sk_user_data;
+	struct pvcalls_fedata *fedata;
+	struct xen_pvcalls_response *rsp;
+	unsigned long flags;
+	int notify;
 
 	if (mappass == NULL)
 		return;
 
-	queue_work(mappass->wq, &mappass->register_work);
+	fedata = mappass->fedata;
+	spin_lock_irqsave(&mappass->copy_lock, flags);
+	if (mappass->reqcopy.cmd == PVCALLS_POLL) {
+		rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
+		rsp->req_id = mappass->reqcopy.req_id;
+		rsp->u.poll.id = mappass->reqcopy.u.poll.id;
+		rsp->cmd = mappass->reqcopy.cmd;
+		rsp->ret = 0;
+
+		mappass->reqcopy.cmd = 0;
+		spin_unlock_irqrestore(&mappass->copy_lock, flags);
+
+		RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify);
+		if (notify)
+			notify_remote_via_irq(mappass->fedata->irq);
+	} else {
+		spin_unlock_irqrestore(&mappass->copy_lock, flags);
+		queue_work(mappass->wq, &mappass->register_work);
+	}
 }
 
 static int pvcalls_back_bind(struct xenbus_device *dev,
@@ -499,6 +521,55 @@ static int pvcalls_back_accept(struct xenbus_device *dev,
 static int pvcalls_back_poll(struct xenbus_device *dev,
 			     struct xen_pvcalls_request *req)
 {
+	struct pvcalls_fedata *fedata;
+	struct sockpass_mapping *mappass;
+	struct xen_pvcalls_response *rsp;
+	struct inet_connection_sock *icsk;
+	struct request_sock_queue *queue;
+	unsigned long flags;
+	int ret;
+	bool data;
+
+	fedata = dev_get_drvdata(&dev->dev);
+
+	mappass = radix_tree_lookup(&fedata->socketpass_mappings, req->u.poll.id);
+	if (mappass == NULL)
+		return -EINVAL;
+
+	/*
+	 * Limitation of the current implementation: only support one
+	 * concurrent accept or poll call on one socket.
+	 */
+	spin_lock_irqsave(&mappass->copy_lock, flags);
+	if (mappass->reqcopy.cmd != 0) {
+		ret = -EINTR;
+		goto out;
+	}
+
+	mappass->reqcopy = *req;
+	icsk = inet_csk(mappass->sock->sk);
+	queue = &icsk->icsk_accept_queue;
+	spin_lock(&queue->rskq_lock);
+	data = queue->rskq_accept_head != NULL;
+	spin_unlock(&queue->rskq_lock);
+	if (data) {
+		mappass->reqcopy.cmd = 0;
+		ret = 0;
+		goto out;
+	}
+	spin_unlock_irqrestore(&mappass->copy_lock, flags);
+
+	/* Tell the caller we don't need to send back a notification yet */
+	return -1;
+
+out:
+	spin_unlock_irqrestore(&mappass->copy_lock, flags);
+
+	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
+	rsp->req_id = req->req_id;
+	rsp->cmd = req->cmd;
+	rsp->u.poll.id = req->u.poll.id;
+	rsp->ret = ret;
 	return 0;
 }
 
-- 
1.9.1

Re: [PATCH v4 12/18] xen/pvcalls: implement poll command

[Boris Ostrovsky]

> @@ -499,6 +521,55 @@ static int pvcalls_back_accept(struct xenbus_device *dev,
>  static int pvcalls_back_poll(struct xenbus_device *dev,
>  			     struct xen_pvcalls_request *req)
>  {
> +	struct pvcalls_fedata *fedata;
> +	struct sockpass_mapping *mappass;
> +	struct xen_pvcalls_response *rsp;
> +	struct inet_connection_sock *icsk;
> +	struct request_sock_queue *queue;
> +	unsigned long flags;
> +	int ret;
> +	bool data;
> +
> +	fedata = dev_get_drvdata(&dev->dev);
> +
> +	mappass = radix_tree_lookup(&fedata->socketpass_mappings, req->u.poll.id);
> +	if (mappass == NULL)
> +		return -EINVAL;
> +
> +	/*
> +	 * Limitation of the current implementation: only support one
> +	 * concurrent accept or poll call on one socket.
> +	 */
> +	spin_lock_irqsave(&mappass->copy_lock, flags);
> +	if (mappass->reqcopy.cmd != 0) {
> +		ret = -EINTR;
> +		goto out;
> +	}
> +
> +	mappass->reqcopy = *req;
> +	icsk = inet_csk(mappass->sock->sk);
> +	queue = &icsk->icsk_accept_queue;
> +	spin_lock(&queue->rskq_lock);
> +	data = queue->rskq_accept_head != NULL;
> +	spin_unlock(&queue->rskq_lock);

What is the purpose of the queue lock here?

-boris

> +	if (data) {
> +		mappass->reqcopy.cmd = 0;
> +		ret = 0;
> +		goto out;
> +	}
> +	spin_unlock_irqrestore(&mappass->copy_lock, flags);
> +
> +	/* Tell the caller we don't need to send back a notification yet */
> +	return -1;
>

Re: [PATCH v4 12/18] xen/pvcalls: implement poll command

[Stefano Stabellini]

On Tue, 20 Jun 2017, Boris Ostrovsky wrote:
> > @@ -499,6 +521,55 @@ static int pvcalls_back_accept(struct xenbus_device *dev,
> >  static int pvcalls_back_poll(struct xenbus_device *dev,
> >  			     struct xen_pvcalls_request *req)
> >  {
> > +	struct pvcalls_fedata *fedata;
> > +	struct sockpass_mapping *mappass;
> > +	struct xen_pvcalls_response *rsp;
> > +	struct inet_connection_sock *icsk;
> > +	struct request_sock_queue *queue;
> > +	unsigned long flags;
> > +	int ret;
> > +	bool data;
> > +
> > +	fedata = dev_get_drvdata(&dev->dev);
> > +
> > +	mappass = radix_tree_lookup(&fedata->socketpass_mappings, req->u.poll.id);
> > +	if (mappass == NULL)
> > +		return -EINVAL;
> > +
> > +	/*
> > +	 * Limitation of the current implementation: only support one
> > +	 * concurrent accept or poll call on one socket.
> > +	 */
> > +	spin_lock_irqsave(&mappass->copy_lock, flags);
> > +	if (mappass->reqcopy.cmd != 0) {
> > +		ret = -EINTR;
> > +		goto out;
> > +	}
> > +
> > +	mappass->reqcopy = *req;
> > +	icsk = inet_csk(mappass->sock->sk);
> > +	queue = &icsk->icsk_accept_queue;
> > +	spin_lock(&queue->rskq_lock);
> > +	data = queue->rskq_accept_head != NULL;
> > +	spin_unlock(&queue->rskq_lock);
> 
> What is the purpose of the queue lock here?

It is only there to protect accesses to rskq_accept_head. Functions that
change rskq_accept_head take this lock, see for example
net/ipv4/inet_connection_sock.c:inet_csk_reqsk_queue_add. I'll add an
in-code comment.


> > +	if (data) {
> > +		mappass->reqcopy.cmd = 0;
> > +		ret = 0;
> > +		goto out;
> > +	}
> > +	spin_unlock_irqrestore(&mappass->copy_lock, flags);
> > +
> > +	/* Tell the caller we don't need to send back a notification yet */
> > +	return -1;

Re: [PATCH v4 12/18] xen/pvcalls: implement poll command

[Boris Ostrovsky]

>>> +
>>> +	mappass->reqcopy = *req;
>>> +	icsk = inet_csk(mappass->sock->sk);
>>> +	queue = &icsk->icsk_accept_queue;
>>> +	spin_lock(&queue->rskq_lock);
>>> +	data = queue->rskq_accept_head != NULL;
>>> +	spin_unlock(&queue->rskq_lock);
>> What is the purpose of the queue lock here?
> It is only there to protect accesses to rskq_accept_head. Functions that
> change rskq_accept_head take this lock, see for example
> net/ipv4/inet_connection_sock.c:inet_csk_reqsk_queue_add. I'll add an
> in-code comment.

I am not sure I follow. You are not changing rskq_accept_head, you are
simply reading it under the lock. It may be set by others to NULL as
soon as you drop the lock, at which point 'data' test below will be
obsolete.

In inet_csk_reqsk_queue_add() it is read and then, based on read result,
is written with a value so a lock is indeed need there.

-boris

>
>
>>> +	if (data) {
>>> +		mappass->reqcopy.cmd = 0;
>>> +		ret = 0;
>>> +		goto out;
>>> +	}
>>> +	spin_unlock_irqrestore(&mappass->copy_lock, flags);
>>> +
>>> +	/* Tell the caller we don't need to send back a notification yet */
>>> +	return -1;

Re: [PATCH v4 12/18] xen/pvcalls: implement poll command

[Stefano Stabellini]

On Wed, 21 Jun 2017, Boris Ostrovsky wrote:
> >>> +
> >>> +	mappass->reqcopy = *req;
> >>> +	icsk = inet_csk(mappass->sock->sk);
> >>> +	queue = &icsk->icsk_accept_queue;
> >>> +	spin_lock(&queue->rskq_lock);
> >>> +	data = queue->rskq_accept_head != NULL;
> >>> +	spin_unlock(&queue->rskq_lock);
> >> What is the purpose of the queue lock here?
> > It is only there to protect accesses to rskq_accept_head. Functions that
> > change rskq_accept_head take this lock, see for example
> > net/ipv4/inet_connection_sock.c:inet_csk_reqsk_queue_add. I'll add an
> > in-code comment.
> 
> I am not sure I follow. You are not changing rskq_accept_head, you are
> simply reading it under the lock. It may be set by others to NULL as
> soon as you drop the lock, at which point 'data' test below will be
> obsolete.
> 
> In inet_csk_reqsk_queue_add() it is read and then, based on read result,
> is written with a value so a lock is indeed need there.

I think you are right. The only thing is that without the lock we might
read a transitory value as the rskq_accept_head reads/writes are not
guaranteed to be atomic. However, I don't think we care about it, since
this is just a != NULL test and, as you wrote, the result could be
obsolete immediately after. I'll drop the lock.



> >
> >
> >>> +	if (data) {
> >>> +		mappass->reqcopy.cmd = 0;
> >>> +		ret = 0;
> >>> +		goto out;
> >>> +	}
> >>> +	spin_unlock_irqrestore(&mappass->copy_lock, flags);
> >>> +
> >>> +	/* Tell the caller we don't need to send back a notification yet */
> >>> +	return -1;
> 

[PATCH v4 13/18] xen/pvcalls: implement release command

[Stefano Stabellini]

Release both active and passive sockets. For active sockets, make sure
to avoid possible conflicts with the ioworker reading/writing to those
sockets concurrently. Set map->release to let the ioworker know
atomically that the socket will be released soon, then wait until the
ioworker finishes (flush_work).

Unmap indexes pages and data rings.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index be85977..afc9575 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -266,12 +266,82 @@ static int pvcalls_back_release_active(struct xenbus_device *dev,
 				       struct pvcalls_fedata *fedata,
 				       struct sock_mapping *map)
 {
+	disable_irq(map->irq);
+	if (map->sock->sk != NULL) {
+		write_lock_bh(&map->sock->sk->sk_callback_lock);
+		map->sock->sk->sk_user_data = NULL;
+		map->sock->sk->sk_data_ready = map->saved_data_ready;
+		write_unlock_bh(&map->sock->sk->sk_callback_lock);
+	}
+
+	atomic_set(&map->release, 1);
+	flush_work(&map->ioworker.register_work);
+
+	down(&fedata->socket_lock);
+	list_del(&map->list);
+	up(&fedata->socket_lock);
+
+	xenbus_unmap_ring_vfree(dev, map->bytes);
+	xenbus_unmap_ring_vfree(dev, (void *)map->ring);
+	unbind_from_irqhandler(map->irq, map);
+
+	sock_release(map->sock);
+	kfree(map);
+
+	return 0;
+}
+
+static int pvcalls_back_release_passive(struct xenbus_device *dev,
+					struct pvcalls_fedata *fedata,
+					struct sockpass_mapping *mappass)
+{
+	if (mappass->sock->sk != NULL) {
+		write_lock_bh(&mappass->sock->sk->sk_callback_lock);
+		mappass->sock->sk->sk_user_data = NULL;
+		mappass->sock->sk->sk_data_ready = mappass->saved_data_ready;
+		write_unlock_bh(&mappass->sock->sk->sk_callback_lock);
+	}
+	down(&fedata->socket_lock);
+	radix_tree_delete(&fedata->socketpass_mappings, mappass->id);
+	sock_release(mappass->sock);
+	flush_workqueue(mappass->wq);
+	destroy_workqueue(mappass->wq);
+	kfree(mappass);
+	up(&fedata->socket_lock);
+
 	return 0;
 }
 
 static int pvcalls_back_release(struct xenbus_device *dev,
 				struct xen_pvcalls_request *req)
 {
+	struct pvcalls_fedata *fedata;
+	struct sock_mapping *map, *n;
+	struct sockpass_mapping *mappass;
+	int ret = 0;
+	struct xen_pvcalls_response *rsp;
+
+	fedata = dev_get_drvdata(&dev->dev);
+
+	list_for_each_entry_safe(map, n, &fedata->socket_mappings, list) {
+		if (map->id == req->u.release.id) {
+			ret = pvcalls_back_release_active(dev, fedata, map);
+			goto out;
+		}
+	}
+	mappass = radix_tree_lookup(&fedata->socketpass_mappings,
+				    req->u.release.id);
+	if (mappass != NULL) {
+		ret = pvcalls_back_release_passive(dev, fedata, mappass);
+		goto out;
+	}
+
+out:
+	rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
+	rsp->req_id = req->req_id;
+	rsp->u.release.id = req->u.release.id;
+	rsp->cmd = req->cmd;
+	rsp->ret = ret;
 	return 0;
 }
 
-- 
1.9.1

Re: [PATCH v4 13/18] xen/pvcalls: implement release command

[Boris Ostrovsky]

> +
> +static int pvcalls_back_release_passive(struct xenbus_device *dev,
> +					struct pvcalls_fedata *fedata,
> +					struct sockpass_mapping *mappass)
> +{
> +	if (mappass->sock->sk != NULL) {
> +		write_lock_bh(&mappass->sock->sk->sk_callback_lock);
> +		mappass->sock->sk->sk_user_data = NULL;
> +		mappass->sock->sk->sk_data_ready = mappass->saved_data_ready;
> +		write_unlock_bh(&mappass->sock->sk->sk_callback_lock);
> +	}
> +	down(&fedata->socket_lock);
> +	radix_tree_delete(&fedata->socketpass_mappings, mappass->id);
> +	sock_release(mappass->sock);
> +	flush_workqueue(mappass->wq);
> +	destroy_workqueue(mappass->wq);
> +	kfree(mappass);
> +	up(&fedata->socket_lock);

Can you raise the semaphore earlier, once the mapping is deleted from
the tree?

Also, why are you not locking the tree in pvcalls_back_accept()?

-boris

Re: [PATCH v4 13/18] xen/pvcalls: implement release command

[Stefano Stabellini]

On Tue, 20 Jun 2017, Boris Ostrovsky wrote:
> > +
> > +static int pvcalls_back_release_passive(struct xenbus_device *dev,
> > +					struct pvcalls_fedata *fedata,
> > +					struct sockpass_mapping *mappass)
> > +{
> > +	if (mappass->sock->sk != NULL) {
> > +		write_lock_bh(&mappass->sock->sk->sk_callback_lock);
> > +		mappass->sock->sk->sk_user_data = NULL;
> > +		mappass->sock->sk->sk_data_ready = mappass->saved_data_ready;
> > +		write_unlock_bh(&mappass->sock->sk->sk_callback_lock);
> > +	}
> > +	down(&fedata->socket_lock);
> > +	radix_tree_delete(&fedata->socketpass_mappings, mappass->id);
> > +	sock_release(mappass->sock);
> > +	flush_workqueue(mappass->wq);
> > +	destroy_workqueue(mappass->wq);
> > +	kfree(mappass);
> > +	up(&fedata->socket_lock);
> 
> Can you raise the semaphore earlier, once the mapping is deleted from
> the tree?

Yes, I think it can.

> Also, why are you not locking the tree in pvcalls_back_accept()?

Good point! Although socket_lock is used to protect insertions and
deletions to socketpass_mappings and socket_mappings, many of the sites
that only access socket_mappings and socketpass_mappings without making
modifications are left unprotected at the moment. I'll fix that, and to
do it I'll move radix_tree_delete out of pvcalls_back_release_passive.

[PATCH v4 14/18] xen/pvcalls: disconnect and module_exit

[Stefano Stabellini]

Implement backend_disconnect. Call pvcalls_back_release_active on active
sockets and pvcalls_back_release_passive on passive sockets.

Implement module_exit by calling backend_disconnect on frontend
connections.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index afc9575..94e4c3f 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -806,6 +806,37 @@ static int backend_connect(struct xenbus_device *dev)
 
 static int backend_disconnect(struct xenbus_device *dev)
 {
+	struct pvcalls_fedata *fedata;
+	struct sock_mapping *map, *n;
+	struct sockpass_mapping *mappass;
+	struct radix_tree_iter iter;
+	void **slot;
+
+
+	fedata = dev_get_drvdata(&dev->dev);
+
+	list_for_each_entry_safe(map, n, &fedata->socket_mappings, list)
+		pvcalls_back_release_active(dev, fedata, map);
+
+	radix_tree_for_each_slot(slot, &fedata->socketpass_mappings, &iter, 0) {
+		mappass = radix_tree_deref_slot(slot);
+		if (!mappass)
+			continue;
+		if (radix_tree_exception(mappass)) {
+			if (radix_tree_deref_retry(mappass))
+				slot = radix_tree_iter_retry(&iter);
+		} else
+			pvcalls_back_release_passive(dev, fedata, mappass);
+	}
+
+	xenbus_unmap_ring_vfree(dev, fedata->sring);
+	unbind_from_irqhandler(fedata->irq, dev);
+
+	list_del(&fedata->list);
+	destroy_workqueue(fedata->wq);
+	kfree(fedata);
+	dev_set_drvdata(&dev->dev, NULL);
+
 	return 0;
 }
 
@@ -999,3 +1030,19 @@ static int __init pvcalls_back_init(void)
 	return 0;
 }
 module_init(pvcalls_back_init);
+
+static void __exit pvcalls_back_fin(void)
+{
+	struct pvcalls_fedata *fedata, *nfedata;
+
+	down(&pvcalls_back_global.frontends_lock);
+	list_for_each_entry_safe(fedata, nfedata, &pvcalls_back_global.frontends,
+				 list) {
+		backend_disconnect(fedata->dev);
+	}
+	up(&pvcalls_back_global.frontends_lock);
+
+	xenbus_unregister_driver(&pvcalls_back_driver);
+}
+
+module_exit(pvcalls_back_fin);
-- 
1.9.1

[PATCH v4 15/18] xen/pvcalls: implement the ioworker functions

[Stefano Stabellini]

We have one ioworker per socket. Each ioworker goes through the list of
outstanding read/write requests. Once all requests have been dealt with,
it returns.

We use one atomic counter per socket for "read" operations and one
for "write" operations to keep track of the reads/writes to do.

We also use one atomic counter ("io") per ioworker to keep track of how
many outstanding requests we have in total assigned to the ioworker. The
ioworker finishes when there are none.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 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 94e4c3f..b9a10b9 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -98,8 +98,35 @@ static int pvcalls_back_release_active(struct xenbus_device *dev,
 				       struct pvcalls_fedata *fedata,
 				       struct sock_mapping *map);
 
+static void pvcalls_conn_back_read(void *opaque)
+{
+}
+
+static int pvcalls_conn_back_write(struct sock_mapping *map)
+{
+	return 0;
+}
+
 static void pvcalls_back_ioworker(struct work_struct *work)
 {
+	struct pvcalls_ioworker *ioworker = container_of(work,
+		struct pvcalls_ioworker, register_work);
+	struct sock_mapping *map = container_of(ioworker, struct sock_mapping,
+		ioworker);
+
+	while (atomic_read(&map->io) > 0) {
+		if (atomic_read(&map->release) > 0) {
+			atomic_set(&map->release, 0);
+			return;
+		}
+
+		if (atomic_read(&map->read) > 0)
+			pvcalls_conn_back_read(map);
+		if (atomic_read(&map->write) > 0)
+			pvcalls_conn_back_write(map);
+
+		atomic_dec(&map->io);
+	}
 }
 
 static int pvcalls_back_socket(struct xenbus_device *dev,
-- 
1.9.1

Re: [PATCH v4 15/18] xen/pvcalls: implement the ioworker functions

[Boris Ostrovsky]

On 06/15/2017 03:09 PM, Stefano Stabellini wrote:
> We have one ioworker per socket. Each ioworker goes through the list of
> outstanding read/write requests. Once all requests have been dealt with,
> it returns.
>
> We use one atomic counter per socket for "read" operations and one
> for "write" operations to keep track of the reads/writes to do.
>
> We also use one atomic counter ("io") per ioworker to keep track of how
> many outstanding requests we have in total assigned to the ioworker. The
> ioworker finishes when there are none.
>
> Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
> CC: boris.ostrovsky@oracle.com
> CC: jgross@suse.com

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

[PATCH v4 16/18] xen/pvcalls: implement read

[Stefano Stabellini]

When an active socket has data available, increment the io and read
counters, and schedule the ioworker.

Implement the read function by reading from the socket, writing the data
to the data ring.

Set in_error on error.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index b9a10b9..65d9eba 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -100,6 +100,81 @@ static int pvcalls_back_release_active(struct xenbus_device *dev,
 
 static void pvcalls_conn_back_read(void *opaque)
 {
+	struct sock_mapping *map = (struct sock_mapping *)opaque;
+	struct msghdr msg;
+	struct kvec vec[2];
+	RING_IDX cons, prod, size, wanted, array_size, masked_prod, masked_cons;
+	int32_t error;
+	struct pvcalls_data_intf *intf = map->ring;
+	struct pvcalls_data *data = &map->data;
+	unsigned long flags;
+	int ret;
+
+	array_size = XEN_FLEX_RING_SIZE(map->ring_order);
+	cons = intf->in_cons;
+	prod = intf->in_prod;
+	error = intf->in_error;
+	/* read the indexes first, then deal with the data */
+	virt_mb();
+
+	if (error)
+		return;
+
+	size = pvcalls_queued(prod, cons, array_size);
+	if (size >= array_size)
+		return;
+	spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
+	if (skb_queue_empty(&map->sock->sk->sk_receive_queue)) {
+		atomic_set(&map->read, 0);
+		spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock,
+				flags);
+		return;
+	}
+	spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
+	wanted = array_size - size;
+	masked_prod = pvcalls_mask(prod, array_size);
+	masked_cons = pvcalls_mask(cons, array_size);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_iter.type = ITER_KVEC|WRITE;
+	msg.msg_iter.count = wanted;
+	if (masked_prod < masked_cons) {
+		vec[0].iov_base = data->in + masked_prod;
+		vec[0].iov_len = wanted;
+		msg.msg_iter.kvec = vec;
+		msg.msg_iter.nr_segs = 1;
+	} else {
+		vec[0].iov_base = data->in + masked_prod;
+		vec[0].iov_len = array_size - masked_prod;
+		vec[1].iov_base = data->in;
+		vec[1].iov_len = wanted - vec[0].iov_len;
+		msg.msg_iter.kvec = vec;
+		msg.msg_iter.nr_segs = 2;
+	}
+
+	atomic_set(&map->read, 0);
+	ret = inet_recvmsg(map->sock, &msg, wanted, MSG_DONTWAIT);
+	WARN_ON(ret > wanted);
+	if (ret == -EAGAIN) /* shouldn't happen */
+		return;
+	if (!ret)
+		ret = -ENOTCONN;
+	spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
+	if (ret > 0 && !skb_queue_empty(&map->sock->sk->sk_receive_queue))
+		atomic_inc(&map->read);
+	spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
+
+	/* write the data, then modify the indexes */
+	virt_wmb();
+	if (ret < 0)
+		intf->in_error = ret;
+	else
+		intf->in_prod = prod + ret;
+	/* update the indexes, then notify the other end */
+	virt_wmb();
+	notify_remote_via_irq(map->irq);
+
+	return;
 }
 
 static int pvcalls_conn_back_write(struct sock_mapping *map)
@@ -172,6 +247,16 @@ static void pvcalls_sk_state_change(struct sock *sock)
 
 static void pvcalls_sk_data_ready(struct sock *sock)
 {
+	struct sock_mapping *map = sock->sk_user_data;
+	struct pvcalls_ioworker *iow;
+
+	if (map == NULL)
+		return;
+
+	iow = &map->ioworker;
+	atomic_inc(&map->read);
+	atomic_inc(&map->io);
+	queue_work(iow->wq, &iow->register_work);
 }
 
 static struct sock_mapping *pvcalls_new_active_socket(
-- 
1.9.1

Re: [PATCH v4 16/18] xen/pvcalls: implement read

[Boris Ostrovsky]

On 06/15/2017 03:09 PM, Stefano Stabellini wrote:
> When an active socket has data available, increment the io and read
> counters, and schedule the ioworker.
>
> Implement the read function by reading from the socket, writing the data
> to the data ring.
>
> Set in_error on error.
>
> Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
> CC: boris.ostrovsky@oracle.com
> CC: jgross@suse.com
> ---
>  drivers/xen/pvcalls-back.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 85 insertions(+)
>
> diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> index b9a10b9..65d9eba 100644
> --- a/drivers/xen/pvcalls-back.c
> +++ b/drivers/xen/pvcalls-back.c
> @@ -100,6 +100,81 @@ static int pvcalls_back_release_active(struct xenbus_device *dev,
>  
>  static void pvcalls_conn_back_read(void *opaque)
>  {
> +	struct sock_mapping *map = (struct sock_mapping *)opaque;
> +	struct msghdr msg;
> +	struct kvec vec[2];
> +	RING_IDX cons, prod, size, wanted, array_size, masked_prod, masked_cons;
> +	int32_t error;
> +	struct pvcalls_data_intf *intf = map->ring;
> +	struct pvcalls_data *data = &map->data;
> +	unsigned long flags;
> +	int ret;
> +
> +	array_size = XEN_FLEX_RING_SIZE(map->ring_order);

I noticed that in the next patch you call this 'ring_size. Can you make
those things consistent? (There may be more than just this variable and,
in fact, perhaps some things can be factored out? There are code
fragments that look similar)

> +	cons = intf->in_cons;
> +	prod = intf->in_prod;
> +	error = intf->in_error;
> +	/* read the indexes first, then deal with the data */
> +	virt_mb();
> +
> +	if (error)
> +		return;
> +
> +	size = pvcalls_queued(prod, cons, array_size);
> +	if (size >= array_size)
> +		return;
> +	spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
> +	if (skb_queue_empty(&map->sock->sk->sk_receive_queue)) {
> +		atomic_set(&map->read, 0);
> +		spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock,
> +				flags);
> +		return;
> +	}
> +	spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
> +	wanted = array_size - size;
> +	masked_prod = pvcalls_mask(prod, array_size);
> +	masked_cons = pvcalls_mask(cons, array_size);
> +
> +	memset(&msg, 0, sizeof(msg));
> +	msg.msg_iter.type = ITER_KVEC|WRITE;
> +	msg.msg_iter.count = wanted;
> +	if (masked_prod < masked_cons) {
> +		vec[0].iov_base = data->in + masked_prod;
> +		vec[0].iov_len = wanted;
> +		msg.msg_iter.kvec = vec;
> +		msg.msg_iter.nr_segs = 1;
> +	} else {
> +		vec[0].iov_base = data->in + masked_prod;
> +		vec[0].iov_len = array_size - masked_prod;
> +		vec[1].iov_base = data->in;
> +		vec[1].iov_len = wanted - vec[0].iov_len;
> +		msg.msg_iter.kvec = vec;
> +		msg.msg_iter.nr_segs = 2;
> +	}


This is probably obvious to everyone but me but can you explain what is
going on here? ;-)


> +
> +	atomic_set(&map->read, 0);

Is this not atomic_dec() by any chance?


-boris

> +	ret = inet_recvmsg(map->sock, &msg, wanted, MSG_DONTWAIT);
> +	WARN_ON(ret > wanted);
> +	if (ret == -EAGAIN) /* shouldn't happen */
> +		return;
> +	if (!ret)
> +		ret = -ENOTCONN;
> +	spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
> +	if (ret > 0 && !skb_queue_empty(&map->sock->sk->sk_receive_queue))
> +		atomic_inc(&map->read);
> +	spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
> +
> +	/* write the data, then modify the indexes */
> +	virt_wmb();
> +	if (ret < 0)
> +		intf->in_error = ret;
> +	else
> +		intf->in_prod = prod + ret;
> +	/* update the indexes, then notify the other end */
> +	virt_wmb();
> +	notify_remote_via_irq(map->irq);
> +
> +	return;
>  }
>  
>  static int pvcalls_conn_back_write(struct sock_mapping *map)
> @@ -172,6 +247,16 @@ static void pvcalls_sk_state_change(struct sock *sock)
>  
>  static void pvcalls_sk_data_ready(struct sock *sock)
>  {
> +	struct sock_mapping *map = sock->sk_user_data;
> +	struct pvcalls_ioworker *iow;
> +
> +	if (map == NULL)
> +		return;
> +
> +	iow = &map->ioworker;
> +	atomic_inc(&map->read);
> +	atomic_inc(&map->io);
> +	queue_work(iow->wq, &iow->register_work);
>  }
>  
>  static struct sock_mapping *pvcalls_new_active_socket(

Re: [PATCH v4 16/18] xen/pvcalls: implement read

[Stefano Stabellini]

On Wed, 21 Jun 2017, Boris Ostrovsky wrote:
> On 06/15/2017 03:09 PM, Stefano Stabellini wrote:
> > When an active socket has data available, increment the io and read
> > counters, and schedule the ioworker.
> >
> > Implement the read function by reading from the socket, writing the data
> > to the data ring.
> >
> > Set in_error on error.
> >
> > Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
> > CC: boris.ostrovsky@oracle.com
> > CC: jgross@suse.com
> > ---
> >  drivers/xen/pvcalls-back.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 85 insertions(+)
> >
> > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> > index b9a10b9..65d9eba 100644
> > --- a/drivers/xen/pvcalls-back.c
> > +++ b/drivers/xen/pvcalls-back.c
> > @@ -100,6 +100,81 @@ static int pvcalls_back_release_active(struct xenbus_device *dev,
> >  
> >  static void pvcalls_conn_back_read(void *opaque)
> >  {
> > +	struct sock_mapping *map = (struct sock_mapping *)opaque;
> > +	struct msghdr msg;
> > +	struct kvec vec[2];
> > +	RING_IDX cons, prod, size, wanted, array_size, masked_prod, masked_cons;
> > +	int32_t error;
> > +	struct pvcalls_data_intf *intf = map->ring;
> > +	struct pvcalls_data *data = &map->data;
> > +	unsigned long flags;
> > +	int ret;
> > +
> > +	array_size = XEN_FLEX_RING_SIZE(map->ring_order);
> 
> I noticed that in the next patch you call this 'ring_size. Can you make
> those things consistent? (There may be more than just this variable and,
> in fact, perhaps some things can be factored out? There are code
> fragments that look similar)

Yes, I'll make them more consistent. I don't think we can actually share
code between the two functions are they do different things.


> > +	cons = intf->in_cons;
> > +	prod = intf->in_prod;
> > +	error = intf->in_error;
> > +	/* read the indexes first, then deal with the data */
> > +	virt_mb();
> > +
> > +	if (error)
> > +		return;
> > +
> > +	size = pvcalls_queued(prod, cons, array_size);
> > +	if (size >= array_size)
> > +		return;
> > +	spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
> > +	if (skb_queue_empty(&map->sock->sk->sk_receive_queue)) {
> > +		atomic_set(&map->read, 0);
> > +		spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock,
> > +				flags);
> > +		return;
> > +	}
> > +	spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
> > +	wanted = array_size - size;
> > +	masked_prod = pvcalls_mask(prod, array_size);
> > +	masked_cons = pvcalls_mask(cons, array_size);
> > +
> > +	memset(&msg, 0, sizeof(msg));
> > +	msg.msg_iter.type = ITER_KVEC|WRITE;
> > +	msg.msg_iter.count = wanted;
> > +	if (masked_prod < masked_cons) {
> > +		vec[0].iov_base = data->in + masked_prod;
> > +		vec[0].iov_len = wanted;
> > +		msg.msg_iter.kvec = vec;
> > +		msg.msg_iter.nr_segs = 1;
> > +	} else {
> > +		vec[0].iov_base = data->in + masked_prod;
> > +		vec[0].iov_len = array_size - masked_prod;
> > +		vec[1].iov_base = data->in;
> > +		vec[1].iov_len = wanted - vec[0].iov_len;
> > +		msg.msg_iter.kvec = vec;
> > +		msg.msg_iter.nr_segs = 2;
> > +	}
> 
> 
> This is probably obvious to everyone but me but can you explain what is
> going on here? ;-)

We are setting up iovecs based on the "in" array (similarly the write
function does the same for the "out" array). Then we are passing the
iovecs to inet_recvmsg to do IO. Depending on the indexes on the array
we need one iovec entry or two, in case we need to wrap around the
circular buffer.

 
> > +
> > +	atomic_set(&map->read, 0);
> 
> Is this not atomic_dec() by any chance?

It is meant to be atomic_set: the idea is that we are going to drain all
the data. If there is any remaming data after inet_recvmsg, we'll
increase map->read again.


> > +	ret = inet_recvmsg(map->sock, &msg, wanted, MSG_DONTWAIT);
> > +	WARN_ON(ret > wanted);
> > +	if (ret == -EAGAIN) /* shouldn't happen */
> > +		return;
> > +	if (!ret)
> > +		ret = -ENOTCONN;
> > +	spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags);
> > +	if (ret > 0 && !skb_queue_empty(&map->sock->sk->sk_receive_queue))
> > +		atomic_inc(&map->read);
> > +	spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags);
> > +
> > +	/* write the data, then modify the indexes */
> > +	virt_wmb();
> > +	if (ret < 0)
> > +		intf->in_error = ret;
> > +	else
> > +		intf->in_prod = prod + ret;
> > +	/* update the indexes, then notify the other end */
> > +	virt_wmb();
> > +	notify_remote_via_irq(map->irq);
> > +
> > +	return;
> >  }
> >  
> >  static int pvcalls_conn_back_write(struct sock_mapping *map)
> > @@ -172,6 +247,16 @@ static void pvcalls_sk_state_change(struct sock *sock)
> >  
> >  static void pvcalls_sk_data_ready(struct sock *sock)
> >  {
> > +	struct sock_mapping *map = sock->sk_user_data;
> > +	struct pvcalls_ioworker *iow;
> > +
> > +	if (map == NULL)
> > +		return;
> > +
> > +	iow = &map->ioworker;
> > +	atomic_inc(&map->read);
> > +	atomic_inc(&map->io);
> > +	queue_work(iow->wq, &iow->register_work);
> >  }
> >  
> >  static struct sock_mapping *pvcalls_new_active_socket(
> 

[PATCH v4 17/18] xen/pvcalls: implement write

[Stefano Stabellini]

When the other end notifies us that there is data to be written
(pvcalls_back_conn_event), increment the io and write counters, and
schedule the ioworker.

Implement the write function called by ioworker by reading the data from
the data ring, writing it to the socket by calling inet_sendmsg.

Set out_error on error.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 74 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 73 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 65d9eba..91ab11b 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -179,7 +179,66 @@ static void pvcalls_conn_back_read(void *opaque)
 
 static int pvcalls_conn_back_write(struct sock_mapping *map)
 {
-	return 0;
+	struct pvcalls_data_intf *intf = map->ring;
+	struct pvcalls_data *data = &map->data;
+	struct msghdr msg;
+	struct kvec vec[2];
+	RING_IDX cons, prod, size, ring_size;
+	int ret;
+
+	cons = intf->out_cons;
+	prod = intf->out_prod;
+	/* read the indexes before dealing with the data */
+	virt_mb();
+
+	ring_size = XEN_FLEX_RING_SIZE(map->ring_order);
+	size = pvcalls_queued(prod, cons, ring_size);
+	if (size == 0)
+		return 0;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_flags |= MSG_DONTWAIT;
+	msg.msg_iter.type = ITER_KVEC|READ;
+	msg.msg_iter.count = size;
+	if (pvcalls_mask(prod, ring_size) > pvcalls_mask(cons, ring_size)) {
+		vec[0].iov_base = data->out + pvcalls_mask(cons, ring_size);
+		vec[0].iov_len = size;
+		msg.msg_iter.kvec = vec;
+		msg.msg_iter.nr_segs = 1;
+	} else {
+		vec[0].iov_base = data->out + pvcalls_mask(cons, ring_size);
+		vec[0].iov_len = ring_size - pvcalls_mask(cons, ring_size);
+		vec[1].iov_base = data->out;
+		vec[1].iov_len = size - vec[0].iov_len;
+		msg.msg_iter.kvec = vec;
+		msg.msg_iter.nr_segs = 2;
+	}
+
+	atomic_set(&map->write, 0);
+	ret = inet_sendmsg(map->sock, &msg, size);
+	if (ret == -EAGAIN || (ret >= 0 && ret < size)) {
+		atomic_inc(&map->write);
+		atomic_inc(&map->io);
+	}
+	if (ret == -EAGAIN)
+		return ret;
+
+	/* write the data, then update the indexes */
+	virt_wmb();
+	if (ret < 0) {
+		intf->out_error = ret;
+	} else {
+		intf->out_error = 0;
+		intf->out_cons = cons + ret;
+		prod = intf->out_prod;
+	}
+	/* update the indexes, then notify the other end */
+	virt_wmb();
+	if (prod != cons + ret)
+		atomic_inc(&map->write);
+	notify_remote_via_irq(map->irq);
+
+	return ret;
 }
 
 static void pvcalls_back_ioworker(struct work_struct *work)
@@ -843,6 +902,19 @@ static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
 
 static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
 {
+	struct sock_mapping *map = sock_map;
+	struct pvcalls_ioworker *iow;
+
+	if (map == NULL || map->sock == NULL || map->sock->sk == NULL ||
+		map->sock->sk->sk_user_data != map)
+		return IRQ_HANDLED;
+
+	iow = &map->ioworker;
+
+	atomic_inc(&map->write);
+	atomic_inc(&map->io);
+	queue_work(iow->wq, &iow->register_work);
+
 	return IRQ_HANDLED;
 }
 
-- 
1.9.1

[PATCH v4 18/18] xen: introduce a Kconfig option to enable the pvcalls backend

[Stefano Stabellini]

Also add pvcalls-back to the Makefile.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/Kconfig  | 12 ++++++++++++
 drivers/xen/Makefile |  1 +
 2 files changed, 13 insertions(+)

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index f15bb3b7..4545561 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -196,6 +196,18 @@ config XEN_PCIDEV_BACKEND
 
 	  If in doubt, say m.
 
+config XEN_PVCALLS_BACKEND
+	bool "XEN PV Calls backend driver"
+	depends on INET && XEN && XEN_BACKEND
+	default n
+	help
+	  Experimental backend for the Xen PV Calls protocol
+	  (https://xenbits.xen.org/docs/unstable/misc/pvcalls.html). It
+	  allows PV Calls frontends to send POSIX calls to the backend,
+	  which implements them.
+
+	  If in doubt, say n.
+
 config XEN_SCSI_BACKEND
 	tristate "XEN SCSI backend driver"
 	depends on XEN && XEN_BACKEND && TARGET_CORE
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 8feab810..480b928 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_XEN_ACPI_PROCESSOR)	+= xen-acpi-processor.o
 obj-$(CONFIG_XEN_EFI)			+= efi.o
 obj-$(CONFIG_XEN_SCSI_BACKEND)		+= xen-scsiback.o
 obj-$(CONFIG_XEN_AUTO_XLATE)		+= xlate_mmu.o
+obj-$(CONFIG_XEN_PVCALLS_BACKEND)	+= pvcalls-back.o
 xen-evtchn-y				:= evtchn.o
 xen-gntdev-y				:= gntdev.o
 xen-gntalloc-y				:= gntalloc.o
-- 
1.9.1