[Xen-devel] [PATCH 2/3] [RFC] User-space grant table device - changes to libxc

[Derek Murray <Derek.Murray@xxxxxxxxxxxx>]

Changes to libxc to enable easy access to the grant table device.

Signed-off-by: Derek Murray <Derek.Murray@xxxxxxxxxxxx>
---
diff -r 809f36b1b685 tools/libxc/xc_linux.c
--- a/tools/libxc/xc_linux.c    Thu Mar 15 10:43:13 2007 +0000
+++ b/tools/libxc/xc_linux.c    Thu Mar 15 17:46:06 2007 +0000
@@ -13,6 +13,7 @@
#include <xen/memory.h>
#include <xen/sys/evtchn.h>
+#include <xen/sys/gntdev.h>
#include <unistd.h>
#include <fcntl.h>
@@ -361,6 +362,143 @@ void discard_file_cache(int fd, int flus
  out:
     errno = saved_errno;
+}
+
+#define GNTTAB_DEV_NAME "/dev/xen/gntdev"
+
+int xc_gnttab_open(void)
+{
+    struct stat st;
+    int fd;
+    int devnum;
+
+    devnum = xc_find_device_number("gntdev");
+
+    /* Make sure any existing device file links to correct device. */
+    if ( (lstat(GNTTAB_DEV_NAME, &st) != 0) || !S_ISCHR(st.st_mode) ||
+         (st.st_rdev != devnum) )
+        (void)unlink(GNTTAB_DEV_NAME);
+
+reopen:
+    if ( (fd = open(GNTTAB_DEV_NAME, O_RDWR)) == -1 )
+    {
+        if ( (errno == ENOENT) &&
+             ((mkdir("/dev/xen", 0755) == 0) || (errno == EEXIST)) &&
+             (mknod(GNTTAB_DEV_NAME, S_IFCHR|0600, devnum) == 0) )
+            goto reopen;
+
+        PERROR("Could not open grant table interface");
+        return -1;
+    }
+
+    return fd;
+}
+
+int xc_gnttab_close(int xcg_handle)
+{
+    return close(xcg_handle);
+}
+
+void *xc_gnttab_map_grant_ref(int xcg_handle,
+                              uint32_t domid,
+                              uint32_t ref,
+                              int prot)
+{
+    struct ioctl_gntdev_map_grant_ref map;
+    struct ioctl_gntdev_grant_ref op;
+    void *addr;
+
+    op.domid = domid;
+    op.ref = ref;
+    map.count = 1;
+    map.refs = &op;
+
+    if (ioctl(xcg_handle, IOCTL_GNTDEV_MAP_GRANT_REF, &map)) {
+        return NULL;
+    }
+
+    addr = mmap(NULL, PAGE_SIZE, prot, MAP_SHARED, xcg_handle,  
map.index);
+    if (addr == MAP_FAILED) {
+        return NULL;
+    }
+
+    return addr;
+}
+
+void *xc_gnttab_map_grant_refs(int xcg_handle,
+                               uint32_t count,
+                               uint32_t domids[count],
+                               uint32_t refs[count],
+                               int prot)
+{
+    struct ioctl_gntdev_map_grant_ref map;
+    struct ioctl_gntdev_grant_ref *ops = malloc(count * sizeof(*ops));
+    void *addr;
+    int i;
+
+    if (ops == NULL) {
+        return NULL;
+    }
+
+    for (i = 0; i < count; ++i) {
+        ops[i].domid = domids[i];
+        ops[i].ref = refs[i];
+    }
+
+    map.count = count;
+    map.refs = ops;
+
+    if (ioctl(xcg_handle, IOCTL_GNTDEV_MAP_GRANT_REF, &map)) {
+        return NULL;
+    }
+
+    printf("Going to mmap() at index %#lx\n", map.index);
+
+    addr = mmap(NULL, PAGE_SIZE * count, prot, MAP_SHARED, xcg_handle,
+                map.index);
+    if (addr == MAP_FAILED) {
+        return NULL;
+    }
+
+    return addr;
+}
+
+int xc_gnttab_munmap(int xcg_handle,
+                     void *start_address,
+                     uint32_t count)
+{
+    struct ioctl_gntdev_get_offset_for_vaddr get_offset;
+    struct ioctl_gntdev_unmap_grant_ref unmap_grant;
+    int rc;
+
+    /* First, it is necessary to get the offset which was initially  
used to
+     * mmap() the pages.
+     */
+    get_offset.vaddr = start_address;
+    if ((rc = ioctl(xcg_handle, IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR,
+                    &get_offset)))
+    {
+        return rc;
+    }
+    if (get_offset.count != count) {
+        errno = -EFAULT;
+        return -EFAULT;
+    }
+
+    /* Next, unmap the memory. */
+    if ((rc = munmap(start_address, count * getpagesize()))) {
+        return rc;
+    }
+
+    /* Finally, unmap the driver slots used to store the grant  
information. */
+    unmap_grant.index = get_offset.offset;
+    unmap_grant.count = count;
+    if ((rc = ioctl(xcg_handle, IOCTL_GNTDEV_UNMAP_GRANT_REF,  
&unmap_grant)))
+    {
+        return rc;
+    }
+
+    return 0;
}
/*
diff -r 809f36b1b685 tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h     Thu Mar 15 10:43:13 2007 +0000
+++ b/tools/libxc/xenctrl.h     Thu Mar 15 17:46:06 2007 +0000
@@ -740,6 +740,62 @@ evtchn_port_t xc_evtchn_pending(int xce_
  */
int xc_evtchn_unmask(int xce_handle, evtchn_port_t port);
+/**************************
+ * GRANT TABLE OPERATIONS *
+ **************************/
+
+/*
+ * Return a handle to the grant table driver, or -1 on failure, in  
which case
+ * errno will be set appropriately.
+ */
+int xc_gnttab_open(void);
+
+/*
+ * Close a handle previously allocated with xc_gnttab_open().
+ */
+int xc_gnttab_close(int xcg_handle);
+
+/*
+ * Memory maps a grant reference from one domain to a local address  
range.
+ * Mappings should be unmapped with xc_gnttab_munmap.  Returns NULL  
on failure.
+ *
+ * @parm xcg_handle a handle on an open grant table interface
+ * @parm domid the domain to map memory from
+ * @parm ref the grant reference ID to map
+ * @parm prot same flag as in mmap()
+ */
+void *xc_gnttab_map_grant_ref(int xcg_handle,
+                              uint32_t domid,
+                              uint32_t ref,
+                              int prot);
+
+/**
+ * Memory maps one or more grant references from one or more domains  
to a
+ * contiguous local address range. Mappings should be unmapped with
+ * xc_gnttab_munmap.  Returns NULL on failure.
+ *
+ * @parm xcg_handle a handle on an open grant table interface
+ * @parm count the number of grant references to be mapped
+ * @parm domids an array of @count domain IDs by which the  
corresponding @refs
+ *              were granted
+ * @parm refs an array of @count grant references to be mapped
+ * @parm prot same flag as in mmap()
+ */
+void *xc_gnttab_map_grant_refs(int xcg_handle,
+                               uint32_t count,
+                               uint32_t domids[count],
+                               uint32_t refs[count],
+                               int prot);
+
+/*
+ * Unmaps the @count pages starting at @start_address, which were  
mapped by a
+ * call to xc_gnttab_map_grant_ref or xc_gnttab_map_grant_refs.  
Returns zero
+ * on success, otherwise sets errno and returns non-zero.
+ */
+int xc_gnttab_munmap(int xcg_handle,
+                     void *start_address,
+                     uint32_t count);
+
int xc_hvm_set_pci_intx_level(
     int xc_handle, domid_t dom,
     uint8_t domain, uint8_t bus, uint8_t device, uint8_t intx,


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