minios: grant table map (gntdev) for minios

I've implemented a grant map for mini-os to support the xc_gnttab_*()
functions, the equivalent of gntdev in linux. This is useful for my
work in putting xenstored in a stub domain.

Signed-off-by: Diego Ongaro <diego.ongaro@citrix.com>

1 files changed, 250 insertions, 0 deletions

diff --git a/extras/mini-os/gntmap.c b/extras/mini-os/gntmap.c
new file mode 100644
index 0000000000..babb96329e
--- /dev/null
+++ b/extras/mini-os/gntmap.c
@@ -0,0 +1,250 @@
+/*
+ * Manages grant mappings from other domains.
+ *
+ * Diego Ongaro <diego.ongaro@citrix.com>, July 2008
+ *
+ * Files of type FTYPE_GNTMAP contain a gntmap, which is an array of
+ * (host address, grant handle) pairs. Grant handles come from a hypervisor map
+ * operation and are needed for the corresponding unmap.
+ *
+ * This is a rather naive implementation in terms of performance. If we start
+ * using it frequently, there's definitely some low-hanging fruit here.
+ *
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <os.h>
+#include <xmalloc.h>
+#include <errno.h>
+#include <xen/grant_table.h>
+#include <inttypes.h>
+#include "gntmap.h"
+
+#define DEFAULT_MAX_GRANTS 128
+
+struct gntmap_entry {
+    unsigned long host_addr;
+    grant_handle_t handle;
+};
+
+static inline int
+gntmap_entry_used(struct gntmap_entry *entry)
+{
+    return entry->host_addr != 0;
+}
+
+static struct gntmap_entry*
+gntmap_find_free_entry(struct gntmap *map)
+{
+    int i;
+
+    for (i = 0; i < map->nentries; i++) {
+        if (!gntmap_entry_used(&map->entries[i]))
+            return &map->entries[i];
+    }
+
+#ifdef GNTMAP_DEBUG
+    printk("gntmap_find_free_entry(map=%p): all %d entries full\n",
+           map, map->nentries);
+#endif
+    return NULL;
+}
+
+static struct gntmap_entry*
+gntmap_find_entry(struct gntmap *map, unsigned long addr)
+{
+    int i;
+
+    for (i = 0; i < map->nentries; i++) {
+        if (map->entries[i].host_addr == addr)
+            return &map->entries[i];
+    }
+    return NULL;
+}
+
+int
+gntmap_set_max_grants(struct gntmap *map, int count)
+{
+#ifdef GNTMAP_DEBUG
+    printk("gntmap_set_max_grants(map=%p, count=%d)\n", map, count);
+#endif
+
+    if (map->nentries != 0)
+        return -EBUSY;
+
+    map->entries = xmalloc_array(struct gntmap_entry, count);
+    if (map->entries == NULL)
+        return -ENOMEM;
+
+    memset(map->entries, 0, sizeof(struct gntmap_entry) * count);
+    map->nentries = count;
+    return 0;
+}
+
+static int
+_gntmap_map_grant_ref(struct gntmap_entry *entry, 
+                      unsigned long host_addr,
+                      uint32_t domid,
+                      uint32_t ref,
+                      int writable)
+{
+    struct gnttab_map_grant_ref op;
+    int rc;
+
+    op.ref = (grant_ref_t) ref;
+    op.dom = (domid_t) domid;
+    op.host_addr = (uint64_t) host_addr;
+    op.flags = GNTMAP_host_map;
+    if (!writable)
+        op.flags |= GNTMAP_readonly;
+
+    rc = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
+    if (rc != 0 || op.status != GNTST_okay) {
+        printk("GNTTABOP_map_grant_ref failed: "
+               "returned %d, status %d\n",
+               rc, op.status);
+        return rc != 0 ? rc : op.status;
+    }
+
+    entry->host_addr = host_addr;
+    entry->handle = op.handle;
+    return 0;
+}
+
+static int
+_gntmap_unmap_grant_ref(struct gntmap_entry *entry)
+{
+    struct gnttab_unmap_grant_ref op;
+    int rc;
+
+    op.host_addr    = (uint64_t) entry->host_addr;
+    op.handle       = entry->handle;
+
+    rc = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1);
+    if (rc != 0 || op.status != GNTST_okay) {
+        printk("GNTTABOP_unmap_grant_ref failed: "
+               "returned %d, status %d\n",
+               rc, op.status);
+        return rc != 0 ? rc : op.status;
+    }
+
+    entry->host_addr = 0;
+    return 0;
+}
+
+int
+gntmap_munmap(struct gntmap *map, unsigned long start_address, int count)
+{
+    int i, rc;
+    struct gntmap_entry *ent;
+
+#ifdef GNTMAP_DEBUG
+    printk("gntmap_munmap(map=%p, start_address=%lx, count=%d)\n",
+           map, start_address, count);
+#endif
+
+    for (i = 0; i < count; i++) {
+        ent = gntmap_find_entry(map, start_address + PAGE_SIZE * i);
+        if (ent == NULL) {
+            printk("gntmap: tried to munmap unknown page\n");
+            return -EINVAL;
+        }
+
+        rc = _gntmap_unmap_grant_ref(ent);
+        if (rc != 0)
+            return rc;
+    }
+
+    return 0;
+}
+
+void*
+gntmap_map_grant_refs(struct gntmap *map, 
+                      uint32_t count,
+                      uint32_t *domids,
+                      int domids_stride,
+                      uint32_t *refs,
+                      int writable)
+{
+    unsigned long addr;
+    struct gntmap_entry *ent;
+    int i;
+
+#ifdef GNTMAP_DEBUG
+    printk("gntmap_map_grant_refs(map=%p, count=%" PRIu32 ", "
+           "domids=%p [%" PRIu32 "...], domids_stride=%d, "
+           "refs=%p [%" PRIu32 "...], writable=%d)\n",
+           map, count, domids, domids[0], domids_stride,
+           refs, refs[0], writable);
+#endif
+
+    (void) gntmap_set_max_grants(map, DEFAULT_MAX_GRANTS);
+
+    addr = allocate_ondemand((unsigned long) count, 1);
+    if (addr == 0)
+        return NULL;
+
+    for (i = 0; i < count; i++) {
+        ent = gntmap_find_free_entry(map);
+        if (ent == NULL ||
+            _gntmap_map_grant_ref(ent,
+                                  addr + PAGE_SIZE * i,
+                                  domids[i * domids_stride],
+                                  refs[i],
+                                  writable) != 0) {
+
+            (void) gntmap_munmap(map, addr, i);
+            return NULL;
+        }
+    }
+
+    return (void*) addr;
+}
+
+void
+gntmap_init(struct gntmap *map)
+{
+#ifdef GNTMAP_DEBUG
+    printk("gntmap_init(map=%p)\n", map);
+#endif
+    map->nentries = 0;
+    map->entries = NULL;
+}
+
+void
+gntmap_fini(struct gntmap *map)
+{
+    struct gntmap_entry *ent;
+    int i;
+
+#ifdef GNTMAP_DEBUG
+    printk("gntmap_fini(map=%p)\n", map);
+#endif
+
+    for (i = 0; i < map->nentries; i++) {
+        ent = &map->entries[i];
+        if (gntmap_entry_used(ent))
+            (void) _gntmap_unmap_grant_ref(ent);
+    }
+
+    xfree(map->entries);
+    map->entries = NULL;
+    map->nentries = 0;
+}