[Xen-devel] [PATCH 2/3] libxc: add xc_gntshr_* functions

[Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>]

These functions and the xc_gntshr device (/dev/xen/gntalloc on linux)
allow applications to create pages shared with other domains.

Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
---
 tools/libxc/xc_gnttab.c      |   27 +++++++++
 tools/libxc/xc_linux_osdep.c |  121 ++++++++++++++++++++++++++++++++++++++++++
 tools/libxc/xc_private.c     |   13 +++++
 tools/libxc/xenctrl.h        |   48 +++++++++++++++++
 tools/libxc/xenctrlosdep.h   |   13 +++++
 5 files changed, 222 insertions(+), 0 deletions(-)

diff --git a/tools/libxc/xc_gnttab.c b/tools/libxc/xc_gnttab.c
index dc7aa0c..ffa3550 100644
--- a/tools/libxc/xc_gnttab.c
+++ b/tools/libxc/xc_gnttab.c
@@ -204,6 +204,33 @@ int xc_gnttab_set_max_grants(xc_gnttab *xcg, uint32_t 
count)
        return xcg->ops->u.gnttab.set_max_grants(xcg, xcg->ops_handle, count);
 }
 
+void *xc_gntshr_share_pages(xc_gntshr *xcg, uint32_t domid,
+                            int count, uint32_t *refs, int writable)
+{
+       return xcg->ops->u.gntshr.share_pages(xcg, xcg->ops_handle, domid,
+                                             count, refs, writable);
+}
+
+void *xc_gntshr_share_page_notify(xc_gntshr *xcg, uint32_t domid,
+                                  uint32_t *ref, int writable,
+                                  uint32_t notify_offset,
+                                  evtchn_port_t notify_port)
+{
+       return xcg->ops->u.gntshr.share_page_notify(xcg, xcg->ops_handle,
+                       domid, ref, writable, notify_offset, notify_port);
+}
+
+/*
+ * Unmaps the @count pages starting at @start_address, which were mapped by a
+ * call to xc_gntshr_share_*. Never logs.
+ */
+int xc_gntshr_munmap(xc_gntshr *xcg, void *start_address, uint32_t count)
+{
+       return xcg->ops->u.gntshr.munmap(xcg, xcg->ops_handle,
+                                        start_address, count);
+}
+
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxc/xc_linux_osdep.c b/tools/libxc/xc_linux_osdep.c
index 8f7718f..871d37c 100644
--- a/tools/libxc/xc_linux_osdep.c
+++ b/tools/libxc/xc_linux_osdep.c
@@ -34,6 +34,7 @@
 #include <xen/memory.h>
 #include <xen/sys/evtchn.h>
 #include <xen/sys/gntdev.h>
+#include <xen/sys/gntalloc.h>
 
 #include "xenctrl.h"
 #include "xenctrlosdep.h"
@@ -718,6 +719,124 @@ static struct xc_osdep_ops linux_gnttab_ops = {
     },
 };
 
+static xc_osdep_handle linux_gntshr_open(xc_gntshr *xcg)
+{
+    int fd = open(DEVXEN "gntalloc", O_RDWR);
+
+    if ( fd == -1 )
+        return XC_OSDEP_OPEN_ERROR;
+
+    return (xc_osdep_handle)fd;
+}
+
+static int linux_gntshr_close(xc_gntshr *xcg, xc_osdep_handle h)
+{
+    int fd = (int)h;
+    return close(fd);
+}
+
+static void *linux_gntshr_share_pages(xc_gntshr *xch, xc_osdep_handle h,
+                                      uint32_t domid, int count,
+                                      uint32_t *refs, int writable)
+{
+       struct ioctl_gntalloc_alloc_gref *gref_info = NULL;
+       int err;
+       void *area = NULL;
+       gref_info = malloc(sizeof(*gref_info) + count * sizeof(uint32_t));
+       if (!gref_info)
+               return NULL;
+       gref_info->domid = domid;
+       gref_info->flags = writable ? GNTALLOC_FLAG_WRITABLE : 0;
+       gref_info->count = count;
+
+       err = ioctl((int)h, IOCTL_GNTALLOC_ALLOC_GREF, gref_info);
+       if (err) {
+               PERROR("linux_gntshr_share_pages: ioctl failed");
+               goto out;
+       }
+
+       area = mmap(NULL, count * XC_PAGE_SIZE, PROT_READ | PROT_WRITE,
+               MAP_SHARED, (int)h, gref_info->index);
+
+       if (area == MAP_FAILED) {
+               area = NULL;
+               PERROR("linux_gntshr_share_pages: mmap failed");
+               goto out;
+       }
+
+       memcpy(refs, gref_info->gref_ids, count * sizeof(uint32_t));
+ out:
+       free(gref_info);
+       return area;
+}
+
+static void *linux_gntshr_share_page_notify(xc_gntshr *xch, xc_osdep_handle h,
+                                            uint32_t domid, uint32_t *ref,
+                                            int writable, uint32_t 
notify_offset,
+                                            evtchn_port_t notify_port)
+{
+       struct ioctl_gntalloc_alloc_gref gref_info;
+       struct ioctl_gntalloc_unmap_notify notify;
+       int err;
+       int fd = (int)h;
+       void *area = NULL;
+       gref_info.domid = domid;
+       gref_info.flags = writable ? GNTALLOC_FLAG_WRITABLE : 0;
+       gref_info.count = 1;
+
+       err = ioctl(fd, IOCTL_GNTALLOC_ALLOC_GREF, &gref_info);
+       if (err) {
+               PERROR("linux_gntshr_share_page_notify: ioctl failed");
+               goto out;
+       }
+
+       area = mmap(NULL, XC_PAGE_SIZE, PROT_READ | PROT_WRITE,
+               MAP_SHARED, fd, gref_info.index);
+
+       if (area == MAP_FAILED) {
+               PERROR("linux_gntshr_share_page_notify: mmap failed");
+               area = NULL;
+               goto out;
+       }
+
+       notify.index = gref_info.index;
+       notify.action = 0;
+       if (notify_offset >= 0) {
+               notify.index += notify_offset;
+               notify.action |= UNMAP_NOTIFY_CLEAR_BYTE;
+       }
+       if (notify_port >= 0) {
+               notify.event_channel_port = notify_port;
+               notify.action |= UNMAP_NOTIFY_SEND_EVENT;
+       }
+       if (notify.action && ioctl(fd, IOCTL_GNTALLOC_SET_UNMAP_NOTIFY, 
&notify)) {
+               PERROR("linux_gntshr_share_page_notify: ioctl SET_UNMAP_NOTIFY 
failed");
+       }
+
+       *ref = gref_info.gref_ids[0];
+ out:
+       return area;
+}
+
+
+static int linux_gntshr_munmap(xc_gntshr *xcg, xc_osdep_handle h,
+                               void *start_address, uint32_t count)
+{
+       return munmap(start_address, count);
+}
+
+static struct xc_osdep_ops linux_gntshr_ops = {
+    .open = &linux_gntshr_open,
+    .close = &linux_gntshr_close,
+
+    .u.gntshr = {
+        .share_pages = &linux_gntshr_share_pages,
+        .share_page_notify = &linux_gntshr_share_page_notify,
+        .munmap = &linux_gntshr_munmap,
+    },
+};
+
+
 static struct xc_osdep_ops *linux_osdep_init(xc_interface *xch, enum 
xc_osdep_type type)
 {
     switch ( type )
@@ -728,6 +847,8 @@ static struct xc_osdep_ops *linux_osdep_init(xc_interface 
*xch, enum xc_osdep_ty
         return &linux_evtchn_ops;
     case XC_OSDEP_GNTTAB:
         return &linux_gnttab_ops;
+    case XC_OSDEP_GNTSHR:
+        return &linux_gntshr_ops;
     default:
         return NULL;
     }
diff --git a/tools/libxc/xc_private.c b/tools/libxc/xc_private.c
index 09c8f23..09a91e7 100644
--- a/tools/libxc/xc_private.c
+++ b/tools/libxc/xc_private.c
@@ -258,6 +258,19 @@ int xc_gnttab_close(xc_gnttab *xcg)
     return xc_interface_close_common(xcg);
 }
 
+xc_gntshr *xc_gntshr_open(xentoollog_logger *logger,
+                             unsigned open_flags)
+{
+    return xc_interface_open_common(logger, NULL, open_flags,
+                                    XC_OSDEP_GNTSHR);
+}
+
+int xc_gntshr_close(xc_gntshr *xcg)
+{
+    return xc_interface_close_common(xcg);
+}
+
+
 static pthread_key_t errbuf_pkey;
 static pthread_once_t errbuf_pkey_once = PTHREAD_ONCE_INIT;
 
diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 7859571..374c705 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -115,6 +115,7 @@
 typedef struct xc_interface_core xc_interface;
 typedef struct xc_interface_core xc_evtchn;
 typedef struct xc_interface_core xc_gnttab;
+typedef struct xc_interface_core xc_gntshr;
 typedef enum xc_error_code xc_error_code;
 
 
@@ -1400,6 +1401,53 @@ grant_entry_v1_t *xc_gnttab_map_table_v1(xc_interface 
*xch, int domid, int *gnt_
 grant_entry_v2_t *xc_gnttab_map_table_v2(xc_interface *xch, int domid, int 
*gnt_num);
 /* Sometimes these don't set errno [fixme], and sometimes they don't log. */
 
+/*
+ * Return an fd onto the grant sharing driver.  Logs errors.
+ */
+xc_gntshr *xc_gntshr_open(xentoollog_logger *logger,
+                         unsigned open_flags);
+
+/*
+ * Close a handle previously allocated with xc_gntshr_open().
+ * Never logs errors.
+ */
+int xc_gntshr_close(xc_gntshr *xcg);
+
+/*
+ * Creates and shares pages with another domain.
+ * 
+ * @parm xcg a handle to an open grant sharing instance
+ * @parm domid the domain to share memory with
+ * @parm count the number of pages to share
+ * @parm refs the grant references of the pages (output)
+ * @parm writable true if the other domain can write to the pages
+ * @return local mapping of the pages
+ */
+void *xc_gntshr_share_pages(xc_gntshr *xcg, uint32_t domid,
+                            int count, uint32_t *refs, int writable);
+
+/*
+ * Creates and shares a page with another domain, with unmap notification.
+ * 
+ * @parm xcg a handle to an open grant sharing instance
+ * @parm domid the domain to share memory with
+ * @parm refs the grant reference of the pages (output)
+ * @parm writable true if the other domain can write to the page
+ * @parm notify_offset The byte offset in the page to use for unmap
+ *                     notification; -1 for none.
+ * @parm notify_port The event channel port to use for unmap notify, or -1
+ * @return local mapping of the page
+ */
+void *xc_gntshr_share_page_notify(xc_gntshr *xcg, uint32_t domid,
+                                  uint32_t *ref, int writable,
+                                  uint32_t notify_offset,
+                                  evtchn_port_t notify_port);
+/*
+ * Unmaps the @count pages starting at @start_address, which were mapped by a
+ * call to xc_gntshr_share_*. Never logs.
+ */
+int xc_gntshr_munmap(xc_gntshr *xcg, void *start_address, uint32_t count);
+
 int xc_physdev_map_pirq(xc_interface *xch,
                         int domid,
                         int index,
diff --git a/tools/libxc/xenctrlosdep.h b/tools/libxc/xenctrlosdep.h
index 01969c5..e1c1ba5 100644
--- a/tools/libxc/xenctrlosdep.h
+++ b/tools/libxc/xenctrlosdep.h
@@ -54,6 +54,7 @@ enum xc_osdep_type {
     XC_OSDEP_PRIVCMD,
     XC_OSDEP_EVTCHN,
     XC_OSDEP_GNTTAB,
+    XC_OSDEP_GNTSHR,
 };
 
 /* Opaque handle internal to the backend */
@@ -129,6 +130,18 @@ struct xc_osdep_ops
                           uint32_t count);
             int (*set_max_grants)(xc_gnttab *xcg, xc_osdep_handle h, uint32_t 
count);
         } gnttab;
+        struct {
+            void *(*share_pages)(xc_gntshr *xcg, xc_osdep_handle h,
+                                 uint32_t domid, int count,
+                                 uint32_t *refs, int writable);
+            void *(*share_page_notify)(xc_gntshr *xcg, xc_osdep_handle h,
+                                       uint32_t domid,
+                                       uint32_t *ref, int writable,
+                                       uint32_t notify_offset,
+                                       evtchn_port_t notify_port);
+            int (*munmap)(xc_gntshr *xcg, xc_osdep_handle h,
+                          void *start_address, uint32_t count);
+        } gntshr;
     } u;
 };
 typedef struct xc_osdep_ops xc_osdep_ops;
-- 
1.7.6


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