Patchwork [RFC,V4,08/13] xenbus_client: extend interface to support mapping / unmapping of multi page ring.

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Submitter Wei Liu
Date Feb. 2, 2012, 4:49 p.m.
Message ID <1328201363-13915-9-git-send-email-wei.liu2@citrix.com>
Download mbox | patch
Permalink /patch/139166/
State RFC
Delegated to: David Miller
Headers show

Comments

Wei Liu - Feb. 2, 2012, 4:49 p.m.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 drivers/xen/xenbus/xenbus_client.c |  282 +++++++++++++++++++++++++-----------
 include/xen/xenbus.h               |   15 ++-
 2 files changed, 206 insertions(+), 91 deletions(-)
Konrad Rzeszutek Wilk - Feb. 3, 2012, 4:55 p.m.
On Thu, Feb 02, 2012 at 04:49:18PM +0000, Wei Liu wrote:
> 

So this does the job but with this patch you introduce a compile bisection
bug, which is a not good. The way around is that in this patch you also
introduce temporary scaffolding so that the drivers can build. Something
as simple as an function that calls the new version, but has the right
arguments. Then the next patch (the one that actually does change
the backends, will back that wrapper out).

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Wei Liu - Feb. 3, 2012, 5:20 p.m.
On Fri, 2012-02-03 at 16:55 +0000, Konrad Rzeszutek Wilk wrote:
> On Thu, Feb 02, 2012 at 04:49:18PM +0000, Wei Liu wrote:
> > 
> 
> So this does the job but with this patch you introduce a compile bisection
> bug, which is a not good. The way around is that in this patch you also
> introduce temporary scaffolding so that the drivers can build. Something
> as simple as an function that calls the new version, but has the right
> arguments. Then the next patch (the one that actually does change
> the backends, will back that wrapper out).
> 

How about squashing these two patches. The changes in backends are
trivial.


Wei.

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Konrad Rzeszutek Wilk - Feb. 3, 2012, 5:35 p.m.
On Fri, Feb 03, 2012 at 05:20:25PM +0000, Wei Liu wrote:
> On Fri, 2012-02-03 at 16:55 +0000, Konrad Rzeszutek Wilk wrote:
> > On Thu, Feb 02, 2012 at 04:49:18PM +0000, Wei Liu wrote:
> > > 
> > 
> > So this does the job but with this patch you introduce a compile bisection
> > bug, which is a not good. The way around is that in this patch you also
> > introduce temporary scaffolding so that the drivers can build. Something
> > as simple as an function that calls the new version, but has the right
> > arguments. Then the next patch (the one that actually does change
> > the backends, will back that wrapper out).
> > 
> 
> How about squashing these two patches. The changes in backends are
> trivial.

That could be done as well.
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Konrad Rzeszutek Wilk - Feb. 6, 2012, 5:21 p.m.
On Fri, Feb 03, 2012 at 05:20:25PM +0000, Wei Liu wrote:
> On Fri, 2012-02-03 at 16:55 +0000, Konrad Rzeszutek Wilk wrote:
> > On Thu, Feb 02, 2012 at 04:49:18PM +0000, Wei Liu wrote:
> > > 
> > 
> > So this does the job but with this patch you introduce a compile bisection
> > bug, which is a not good. The way around is that in this patch you also
> > introduce temporary scaffolding so that the drivers can build. Something
> > as simple as an function that calls the new version, but has the right
> > arguments. Then the next patch (the one that actually does change
> > the backends, will back that wrapper out).
> > 
> 
> How about squashing these two patches. The changes in backends are
> trivial.


One thing I forgot to mention is that since the backends touch different
subsystems maintainers tree - you will need to get Acks from all of them
on a single patch. That should not be an technical issue - except that some
maintainers can take longer to respond - so your whole patchset might
be delayed by that.
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Wei Liu - Feb. 6, 2012, 5:30 p.m.
On Mon, 2012-02-06 at 17:21 +0000, Konrad Rzeszutek Wilk wrote:
> One thing I forgot to mention is that since the backends touch different
> subsystems maintainers tree - you will need to get Acks from all of them
> on a single patch. That should not be an technical issue - except that some
> maintainers can take longer to respond - so your whole patchset might
> be delayed by that.

Sure, that's not a big problem.


Wei.

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Patch

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index 566d2ad..d73b9c6 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -53,14 +53,16 @@  struct xenbus_map_node {
 		struct vm_struct *area; /* PV */
 		struct page *page;     /* HVM */
 	};
-	grant_handle_t handle;
+	grant_handle_t handle[XENBUS_MAX_RING_PAGES];
+	unsigned int   nr_handles;
 };
 
 static DEFINE_SPINLOCK(xenbus_valloc_lock);
 static LIST_HEAD(xenbus_valloc_pages);
 
 struct xenbus_ring_ops {
-	int (*map)(struct xenbus_device *dev, int gnt, void **vaddr);
+	int (*map)(struct xenbus_device *dev, int gnt[], int nr_gnts,
+		   void **vaddr);
 	int (*unmap)(struct xenbus_device *dev, void *vaddr);
 };
 
@@ -356,17 +358,38 @@  static void xenbus_switch_fatal(struct xenbus_device *dev, int depth, int err,
 /**
  * xenbus_grant_ring
  * @dev: xenbus device
- * @ring_mfn: mfn of ring to grant
-
- * Grant access to the given @ring_mfn to the peer of the given device.  Return
- * 0 on success, or -errno on error.  On error, the device will switch to
- * XenbusStateClosing, and the error will be saved in the store.
+ * @vaddr: starting virtual address of the ring
+ * @nr_pages: number of page to be granted
+ * @grefs: grant reference array to be filled in
+ * Grant access to the given @vaddr to the peer of the given device.
+ * Then fill in @grefs with grant references.  Return 0 on success, or
+ * -errno on error.  On error, the device will switch to
+ * XenbusStateClosing, and the first error will be saved in the store.
  */
-int xenbus_grant_ring(struct xenbus_device *dev, unsigned long ring_mfn)
+int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
+		      int nr_pages, int grefs[])
 {
-	int err = gnttab_grant_foreign_access(dev->otherend_id, ring_mfn, 0);
-	if (err < 0)
-		xenbus_dev_fatal(dev, err, "granting access to ring page");
+	int i;
+	int err;
+
+	for (i = 0; i < nr_pages; i++) {
+		unsigned long addr = (unsigned long)vaddr +
+			(PAGE_SIZE * i);
+		err = gnttab_grant_foreign_access(dev->otherend_id,
+						  virt_to_mfn(addr), 0);
+		if (err < 0) {
+			xenbus_dev_fatal(dev, err,
+					 "granting access to ring page");
+			goto fail;
+		}
+		grefs[i] = err;
+	}
+
+	return 0;
+
+fail:
+	for ( ; i >= 0; i--)
+		gnttab_end_foreign_access_ref(grefs[i], 0);
 	return err;
 }
 EXPORT_SYMBOL_GPL(xenbus_grant_ring);
@@ -447,7 +470,8 @@  EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
 /**
  * xenbus_map_ring_valloc
  * @dev: xenbus device
- * @gnt_ref: grant reference
+ * @gnt_ref: grant reference array
+ * @nr_grefs: number of grant reference
  * @vaddr: pointer to address to be filled out by mapping
  *
  * Based on Rusty Russell's skeleton driver's map_page.
@@ -458,52 +482,74 @@  EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
  * or -ENOMEM on error. If an error is returned, device will switch to
  * XenbusStateClosing and the error message will be saved in XenStore.
  */
-int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
+int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref[],
+			   int nr_grefs, void **vaddr)
 {
-	return ring_ops->map(dev, gnt_ref, vaddr);
+	return ring_ops->map(dev, gnt_ref, nr_grefs, vaddr);
 }
 EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
 
+static int __xenbus_unmap_ring_vfree_pv(struct xenbus_device *dev,
+					struct xenbus_map_node *node);
+
 static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev,
-				     int gnt_ref, void **vaddr)
+				     int gnt_ref[], int nr_grefs, void **vaddr)
 {
-	struct gnttab_map_grant_ref op = {
-		.flags = GNTMAP_host_map | GNTMAP_contains_pte,
-		.ref   = gnt_ref,
-		.dom   = dev->otherend_id,
-	};
+	struct gnttab_map_grant_ref op[XENBUS_MAX_RING_PAGES];
 	struct xenbus_map_node *node;
 	struct vm_struct *area;
-	pte_t *pte;
+	pte_t *pte[XENBUS_MAX_RING_PAGES];
+	int i;
+	int err = 0;
 
 	*vaddr = NULL;
 
+	if (nr_grefs > XENBUS_MAX_RING_PAGES)
+		return -EINVAL;
+
 	node = kzalloc(sizeof(*node), GFP_KERNEL);
 	if (!node)
 		return -ENOMEM;
 
-	area = alloc_vm_area(PAGE_SIZE, &pte);
+	area = alloc_vm_area(PAGE_SIZE * nr_grefs, pte);
 	if (!area) {
 		kfree(node);
 		return -ENOMEM;
 	}
 
-	op.host_addr = arbitrary_virt_to_machine(pte).maddr;
+	for (i = 0; i < nr_grefs; i++) {
+		op[i].flags = GNTMAP_host_map | GNTMAP_contains_pte,
+		op[i].ref   = gnt_ref[i],
+		op[i].dom   = dev->otherend_id,
+		op[i].host_addr = arbitrary_virt_to_machine(pte[i]).maddr;
+	};
 
-	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
+	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, op, nr_grefs))
 		BUG();
 
-	if (op.status != GNTST_okay) {
-		free_vm_area(area);
-		kfree(node);
-		xenbus_dev_fatal(dev, op.status,
+	node->nr_handles = nr_grefs;
+	node->area = area;
+
+	for (i = 0; i < nr_grefs; i++) {
+		if (op[i].status != GNTST_okay) {
+			err = op[i].status;
+			node->handle[i] = INVALID_GRANT_HANDLE;
+			continue;
+		}
+		node->handle[i] = op[i].handle;
+	}
+
+	if (err != 0) {
+		for (i = 0; i < nr_grefs; i++)
+			xenbus_dev_fatal(dev, op[i].status,
 				 "mapping in shared page %d from domain %d",
-				 gnt_ref, dev->otherend_id);
-		return op.status;
+				 gnt_ref[i], dev->otherend_id);
+
+		__xenbus_unmap_ring_vfree_pv(dev, node);
+
+		return err;
 	}
 
-	node->handle = op.handle;
-	node->area = area;
 
 	spin_lock(&xenbus_valloc_lock);
 	list_add(&node->next, &xenbus_valloc_pages);
@@ -514,28 +560,34 @@  static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev,
 }
 
 static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev,
-				      int gnt_ref, void **vaddr)
+				      int gnt_ref[], int nr_grefs, void **vaddr)
 {
 	struct xenbus_map_node *node;
 	int err;
 	void *addr;
 
+	if (nr_grefs > XENBUS_MAX_RING_PAGES)
+		return -EINVAL;
+
 	*vaddr = NULL;
 
 	node = kzalloc(sizeof(*node), GFP_KERNEL);
 	if (!node)
 		return -ENOMEM;
 
-	err = alloc_xenballooned_pages(1, &node->page, false /* lowmem */);
+	err = alloc_xenballooned_pages(nr_grefs, &node->page,
+				       false /* lowmem */);
 	if (err)
 		goto out_err;
 
 	addr = pfn_to_kaddr(page_to_pfn(node->page));
 
-	err = xenbus_map_ring(dev, gnt_ref, &node->handle, addr);
+	err = xenbus_map_ring(dev, gnt_ref, nr_grefs, node->handle, addr);
 	if (err)
 		goto out_err;
 
+	node->nr_handles = nr_grefs;
+
 	spin_lock(&xenbus_valloc_lock);
 	list_add(&node->next, &xenbus_valloc_pages);
 	spin_unlock(&xenbus_valloc_lock);
@@ -544,7 +596,7 @@  static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev,
 	return 0;
 
  out_err:
-	free_xenballooned_pages(1, &node->page);
+	free_xenballooned_pages(nr_grefs, &node->page);
 	kfree(node);
 	return err;
 }
@@ -553,36 +605,52 @@  static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev,
 /**
  * xenbus_map_ring
  * @dev: xenbus device
- * @gnt_ref: grant reference
- * @handle: pointer to grant handle to be filled
+ * @gnt_ref: grant reference array
+ * @nr_grefs: number of grant reference
+ * @handle: pointer to grant handle array to be filled, mind the size
  * @vaddr: address to be mapped to
  *
- * Map a page of memory into this domain from another domain's grant table.
+ * Map pages of memory into this domain from another domain's grant table.
  * xenbus_map_ring does not allocate the virtual address space (you must do
- * this yourself!). It only maps in the page to the specified address.
+ * this yourself!). It only maps in the pages to the specified address.
  * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
  * or -ENOMEM on error. If an error is returned, device will switch to
- * XenbusStateClosing and the error message will be saved in XenStore.
+ * XenbusStateClosing and the last error message will be saved in XenStore.
  */
-int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref,
-		    grant_handle_t *handle, void *vaddr)
+int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref[], int nr_grefs,
+		    grant_handle_t handle[], void *vaddr)
 {
-	struct gnttab_map_grant_ref op;
-
-	gnttab_set_map_op(&op, (phys_addr_t)vaddr, GNTMAP_host_map, gnt_ref,
-			  dev->otherend_id);
+	struct gnttab_map_grant_ref op[XENBUS_MAX_RING_PAGES];
+	int i;
+	int err = GNTST_okay;	/* 0 */
+
+	for (i = 0; i < nr_grefs; i++) {
+		unsigned long addr = (unsigned long)vaddr +
+			(PAGE_SIZE * i);
+		gnttab_set_map_op(&op[i], (phys_addr_t)addr,
+				  GNTMAP_host_map, gnt_ref[i],
+				  dev->otherend_id);
+	}
 
-	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
+	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, op, nr_grefs))
 		BUG();
 
-	if (op.status != GNTST_okay) {
-		xenbus_dev_fatal(dev, op.status,
+
+	for (i = 0; i < nr_grefs; i++) {
+		if (op[i].status != GNTST_okay) {
+			err = op[i].status;
+			xenbus_dev_fatal(dev, err,
 				 "mapping in shared page %d from domain %d",
-				 gnt_ref, dev->otherend_id);
-	} else
-		*handle = op.handle;
+				 gnt_ref[i], dev->otherend_id);
+			handle[i] = INVALID_GRANT_HANDLE;
+		} else
+			handle[i] = op[i].handle;
+	}
+
+	if (err != GNTST_okay)
+		xenbus_unmap_ring(dev, handle, nr_grefs, vaddr);
 
-	return op.status;
+	return err;
 }
 EXPORT_SYMBOL_GPL(xenbus_map_ring);
 
@@ -605,13 +673,53 @@  int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
 }
 EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree);
 
+static int __xenbus_unmap_ring_vfree_pv(struct xenbus_device *dev,
+					struct xenbus_map_node *node)
+{
+	struct gnttab_unmap_grant_ref op[XENBUS_MAX_RING_PAGES];
+	unsigned int level;
+	int i, j;
+	int err = GNTST_okay;
+
+	j = 0;
+	for (i = 0; i < node->nr_handles; i++) {
+		unsigned long vaddr = (unsigned long)node->area->addr +
+			(PAGE_SIZE * i);
+		if (node->handle[i] != INVALID_GRANT_HANDLE) {
+			memset(&op[j], 0, sizeof(op[0]));
+			op[j].host_addr = arbitrary_virt_to_machine(
+				lookup_address(vaddr, &level)).maddr;
+			op[j].handle = node->handle[i];
+			j++;
+			node->handle[i] = INVALID_GRANT_HANDLE;
+		}
+	}
+
+	if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, op, j))
+		BUG();
+
+	node->nr_handles = 0;
+
+	for (i = 0; i < j; i++) {
+		if (op[i].status != GNTST_okay) {
+			err = op[i].status;
+			xenbus_dev_error(dev, err,
+				 "unmapping page %d at handle %d error %d",
+				 i, op[i].handle, err);
+		}
+	}
+
+	if (err == GNTST_okay)
+		free_vm_area(node->area);
+
+	kfree(node);
+
+	return err;
+}
+
 static int xenbus_unmap_ring_vfree_pv(struct xenbus_device *dev, void *vaddr)
 {
 	struct xenbus_map_node *node;
-	struct gnttab_unmap_grant_ref op = {
-		.host_addr = (unsigned long)vaddr,
-	};
-	unsigned int level;
 
 	spin_lock(&xenbus_valloc_lock);
 	list_for_each_entry(node, &xenbus_valloc_pages, next) {
@@ -630,29 +738,14 @@  static int xenbus_unmap_ring_vfree_pv(struct xenbus_device *dev, void *vaddr)
 		return GNTST_bad_virt_addr;
 	}
 
-	op.handle = node->handle;
-	op.host_addr = arbitrary_virt_to_machine(
-		lookup_address((unsigned long)vaddr, &level)).maddr;
-
-	if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
-		BUG();
-
-	if (op.status == GNTST_okay)
-		free_vm_area(node->area);
-	else
-		xenbus_dev_error(dev, op.status,
-				 "unmapping page at handle %d error %d",
-				 node->handle, op.status);
-
-	kfree(node);
-	return op.status;
+	return __xenbus_unmap_ring_vfree_pv(dev, node);
 }
 
 static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
 {
 	int rv;
 	struct xenbus_map_node *node;
-	void *addr;
+	void *addr = NULL;
 
 	spin_lock(&xenbus_valloc_lock);
 	list_for_each_entry(node, &xenbus_valloc_pages, next) {
@@ -672,10 +765,10 @@  static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
 		return GNTST_bad_virt_addr;
 	}
 
-	rv = xenbus_unmap_ring(dev, node->handle, addr);
+	rv = xenbus_unmap_ring(dev, node->handle, node->nr_handles, addr);
 
 	if (!rv)
-		free_xenballooned_pages(1, &node->page);
+		free_xenballooned_pages(node->nr_handles, &node->page);
 	else
 		WARN(1, "Leaking %p\n", vaddr);
 
@@ -687,6 +780,7 @@  static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
  * xenbus_unmap_ring
  * @dev: xenbus device
  * @handle: grant handle
+ * @nr_handles: number of grant handle
  * @vaddr: addr to unmap
  *
  * Unmap a page of memory in this domain that was imported from another domain.
@@ -694,21 +788,37 @@  static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
  * (see xen/include/interface/grant_table.h).
  */
 int xenbus_unmap_ring(struct xenbus_device *dev,
-		      grant_handle_t handle, void *vaddr)
+		      grant_handle_t handle[], int nr_handles,
+		      void *vaddr)
 {
-	struct gnttab_unmap_grant_ref op;
-
-	gnttab_set_unmap_op(&op, (phys_addr_t)vaddr, GNTMAP_host_map, handle);
+	struct gnttab_unmap_grant_ref op[XENBUS_MAX_RING_PAGES];
+	int i, j;
+	int err = GNTST_okay;
+
+	j = 0;
+	for (i = 0; i < nr_handles; i++) {
+		unsigned long addr = (unsigned long)vaddr +
+			(PAGE_SIZE * i);
+		if (handle[i] != INVALID_GRANT_HANDLE) {
+			gnttab_set_unmap_op(&op[j++], (phys_addr_t)addr,
+					    GNTMAP_host_map, handle[i]);
+			handle[i] = INVALID_GRANT_HANDLE;
+		}
+	}
 
-	if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
+	if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, op, j))
 		BUG();
 
-	if (op.status != GNTST_okay)
-		xenbus_dev_error(dev, op.status,
+	for (i = 0; i < j; i++) {
+		if (op[i].status != GNTST_okay) {
+			err = op[i].status;
+			xenbus_dev_error(dev, err,
 				 "unmapping page at handle %d error %d",
-				 handle, op.status);
+				 handle[i], err);
+		}
+	}
 
-	return op.status;
+	return err;
 }
 EXPORT_SYMBOL_GPL(xenbus_unmap_ring);
 
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index e8c599b..284647f 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -46,6 +46,10 @@ 
 #include <xen/interface/io/xenbus.h>
 #include <xen/interface/io/xs_wire.h>
 
+#define XENBUS_MAX_RING_PAGE_ORDER 2
+#define XENBUS_MAX_RING_PAGES      4
+#define INVALID_GRANT_HANDLE       (~0U)
+
 /* Register callback to watch this node. */
 struct xenbus_watch
 {
@@ -195,15 +199,16 @@  int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch,
 			 const char *pathfmt, ...);
 
 int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state new_state);
-int xenbus_grant_ring(struct xenbus_device *dev, unsigned long ring_mfn);
+int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
+		      int nr_pages, int grefs[]);
 int xenbus_map_ring_valloc(struct xenbus_device *dev,
-			   int gnt_ref, void **vaddr);
-int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref,
-			   grant_handle_t *handle, void *vaddr);
+			   int gnt_ref[], int nr_grefs, void **vaddr);
+int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref[], int nr_grefs,
+			   grant_handle_t handle[], void *vaddr);
 
 int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr);
 int xenbus_unmap_ring(struct xenbus_device *dev,
-		      grant_handle_t handle, void *vaddr);
+		      grant_handle_t handle[], int nr_handles, void *vaddr);
 
 int xenbus_alloc_evtchn(struct xenbus_device *dev, int *port);
 int xenbus_bind_evtchn(struct xenbus_device *dev, int remote_port, int *port);