Update memshr API and tools

This patch is the folded version of API updates, along with the associated tool
changes to ensure that the build is always consistent.

API updates:
- The source domain in the sharing calls is no longer assumed to be dom0.
- Previously, the mem sharing code would return an opaque handle to index
  shared pages (and nominees) in its global hash table.  By removing the hash
  table, the handle becomes a version, to avoid sharing a stale version of a
  page. Thus, libxc wrappers and tools need to be updated to recall the share
  functions with the information needed to fetch the page (which they readily
  have).

Tool updates:
The only (in-tree, that we know of) consumer of the mem sharing API is the
memshr tool. This is updated to use the new API.

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Signed-off-by: Adin Scannell <adin@scannell.ca>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Tim Deegan <tim@xen.org>

4 files changed, 58 insertions, 29 deletions

diff --git a/tools/memshr/bidir-daemon.c b/tools/memshr/bidir-daemon.c
index a7cb3c1534..a601837650 100644
--- a/tools/memshr/bidir-daemon.c
+++ b/tools/memshr/bidir-daemon.c
@@ -19,16 +19,25 @@
 #include <pthread.h>
 #include <inttypes.h>
 #include <unistd.h>
+#include <errno.h>
 
 #include "bidir-hash.h"
 #include "memshr-priv.h"
 
 static struct blockshr_hash *blks_hash;
 
+/* Callback in the iterator, remember this value, and leave */
+int find_one(vbdblk_t k, share_tuple_t v, void *priv)
+{
+    share_tuple_t *rv = (share_tuple_t *) priv;
+    *rv = v;
+    /* Break out of iterator loop */
+    return 1;
+}
+
 void* bidir_daemon(void *unused)
 {
     uint32_t nr_ent, max_nr_ent, tab_size, max_load, min_load;
-    static uint64_t shrhnd = 1;
 
     while(1)
     {
@@ -41,20 +50,30 @@ void* bidir_daemon(void *unused)
         /* Remove some hints as soon as we get to 90% capacity */ 
         if(10 * nr_ent > 9 * max_nr_ent)
         {
-            uint64_t next_remove = shrhnd;
+            share_tuple_t next_remove;
             int to_remove;
             int ret;
 
             to_remove = 0.1 * max_nr_ent; 
             while(to_remove > 0) 
             {
-                ret = blockshr_shrhnd_remove(blks_hash, next_remove, NULL);
-                if(ret < 0)
+                /* We use the iterator to get one entry */
+                next_remove.handle = 0;
+                ret = blockshr_hash_iterator(blks_hash, find_one, &next_remove);
+
+                if ( !ret )
+                    if ( next_remove.handle == 0 )
+                        ret = -ESRCH;
+
+                if ( !ret )
+                    ret = blockshr_shrhnd_remove(blks_hash, next_remove, NULL);
+
+                if(ret <= 0)
                 {
                     /* We failed to remove an entry, because of a serious hash
                      * table error */
                     DPRINTF("Could not remove handle %"PRId64", error: %d\n",
-                            next_remove, ret);
+                            next_remove.handle, ret);
                     /* Force to exit the loop early */
                     to_remove = 0;
                 } else 
@@ -62,12 +81,7 @@ void* bidir_daemon(void *unused)
                 {
                     /* Managed to remove the entry. Note next_remove not
                      * incremented, in case there are duplicates */
-                    shrhnd = next_remove;
                     to_remove--;
-                } else
-                {
-                    /* Failed to remove, because there is no such handle */
-                    next_remove++;
                 }
             }
         }
diff --git a/tools/memshr/bidir-hash.h b/tools/memshr/bidir-hash.h
index 5c4acae3e0..cc9166fa47 100644
--- a/tools/memshr/bidir-hash.h
+++ b/tools/memshr/bidir-hash.h
@@ -20,6 +20,7 @@
 #define __BIDIR_HASH_H__
 
 #include <stdint.h>
+#include <string.h>
 #include "memshr-priv.h"
 
 typedef struct vbdblk {
@@ -81,15 +82,16 @@ static int fgprtshr_mfn_cmp(uint32_t m1, uint32_t m2)
 #undef BIDIR_VALUE
 #undef BIDIR_KEY_T
 #undef BIDIR_VALUE_T
+
 /* TODO better hashes! */
 static inline uint32_t blockshr_block_hash(vbdblk_t block)
 {
     return (uint32_t)(block.sec) ^ (uint32_t)(block.disk_id);
 }
 
-static inline uint32_t blockshr_shrhnd_hash(uint64_t shrhnd)
+static inline uint32_t blockshr_shrhnd_hash(share_tuple_t shrhnd)
 {
-    return (uint32_t)shrhnd;
+    return ((uint32_t) shrhnd.handle);
 }
 
 static inline int blockshr_block_cmp(vbdblk_t b1, vbdblk_t b2)
@@ -97,15 +99,15 @@ static inline int blockshr_block_cmp(vbdblk_t b1, vbdblk_t b2)
     return (b1.sec == b2.sec) && (b1.disk_id == b2.disk_id);
 }
 
-static inline int blockshr_shrhnd_cmp(uint64_t h1, uint64_t h2)
+static inline int blockshr_shrhnd_cmp(share_tuple_t h1, share_tuple_t h2)
 {
-    return (h1 == h2);
+    return ( !memcmp(&h1, &h2, sizeof(share_tuple_t)) );
 }
 #define BIDIR_NAME_PREFIX       blockshr
 #define BIDIR_KEY               block
 #define BIDIR_VALUE             shrhnd
 #define BIDIR_KEY_T             vbdblk_t
-#define BIDIR_VALUE_T           uint64_t
+#define BIDIR_VALUE_T           share_tuple_t
 #include "bidir-namedefs.h"
 
 #endif /* BLOCK_MAP */
diff --git a/tools/memshr/interface.c b/tools/memshr/interface.c
index 91cf7c6c1a..b4d6d4e190 100644
--- a/tools/memshr/interface.c
+++ b/tools/memshr/interface.c
@@ -145,16 +145,17 @@ void memshr_vbd_image_put(uint16_t memshr_id)
     
 int memshr_vbd_issue_ro_request(char *buf,
                                 grant_ref_t gref,
-                                uint16_t file_id, 
+                                uint16_t file_id,
                                 uint64_t sec, 
                                 int secs,
-                                uint64_t *hnd)
+                                share_tuple_t *hnd)
 {
     vbdblk_t blk;
-    uint64_t s_hnd, c_hnd;
+    share_tuple_t source_st, client_st;
+    uint64_t c_hnd;
     int ret;
 
-    *hnd = 0;
+    *hnd = (share_tuple_t){ 0, 0, 0 };
     if(!vbd_info.enabled) 
         return -1;
 
@@ -169,26 +170,31 @@ int memshr_vbd_issue_ro_request(char *buf,
     /* If page couldn't be made sharable, we cannot do anything about it */
     if(ret != 0)
         return -3;
-    *hnd = c_hnd;
+
+    client_st = (share_tuple_t){ vbd_info.domid, gref, c_hnd };
+    *hnd = client_st;
 
     /* Check if we've read matching disk block previously */
     blk.sec     = sec;
     blk.disk_id = file_id;
-    if(blockshr_block_lookup(memshr.blks, blk, &s_hnd) > 0)
+    if(blockshr_block_lookup(memshr.blks, blk, &source_st) > 0)
     {
-        ret = xc_memshr_share(vbd_info.xc_handle, s_hnd, c_hnd);
+        ret = xc_memshr_share_grefs(vbd_info.xc_handle, source_st.domain, source_st.frame, 
+                                    source_st.handle, vbd_info.domid, gref, c_hnd);
         if(!ret) return 0;
         /* Handles failed to be shared => at least one of them must be invalid,
            remove the relevant ones from the map */
         switch(ret)
         {
             case XEN_DOMCTL_MEM_SHARING_S_HANDLE_INVALID:
-                ret = blockshr_shrhnd_remove(memshr.blks, s_hnd, NULL);
-                if(ret) DPRINTF("Could not rm invl s_hnd: %"PRId64"\n", s_hnd);
+                ret = blockshr_shrhnd_remove(memshr.blks, source_st, NULL);
+                if(ret) DPRINTF("Could not rm invl s_hnd: %u %"PRId64" %"PRId64"\n", 
+                                    source_st.domain, source_st.frame, source_st.handle);
                 break;
             case XEN_DOMCTL_MEM_SHARING_C_HANDLE_INVALID:
-                ret = blockshr_shrhnd_remove(memshr.blks, c_hnd, NULL);
-                if(ret) DPRINTF("Could not rm invl c_hnd: %"PRId64"\n", c_hnd);
+                ret = blockshr_shrhnd_remove(memshr.blks, client_st, NULL);
+                if(ret) DPRINTF("Could not rm invl c_hnd: %u %"PRId64" %"PRId64"\n", 
+                                    client_st.domain, client_st.frame, client_st.handle);
                 break;
             default:
                 break;
@@ -199,7 +205,7 @@ int memshr_vbd_issue_ro_request(char *buf,
     return -4;
 }
 
-void memshr_vbd_complete_ro_request(uint64_t hnd,
+void memshr_vbd_complete_ro_request(share_tuple_t hnd,
                                     uint16_t file_id, 
                                     uint64_t sec, 
                                     int secs)
diff --git a/tools/memshr/memshr.h b/tools/memshr/memshr.h
index 24dd04c4f3..32c1d815da 100644
--- a/tools/memshr/memshr.h
+++ b/tools/memshr/memshr.h
@@ -25,6 +25,13 @@
 
 typedef uint64_t xen_mfn_t;
 
+typedef struct share_tuple 
+{
+    uint32_t domain;
+    uint64_t frame;
+    uint64_t handle;
+} share_tuple_t;
+
 extern void memshr_set_domid(int domid);
 extern void memshr_daemon_initialize(void);
 extern void memshr_vbd_initialize(void);
@@ -35,9 +42,9 @@ extern int memshr_vbd_issue_ro_request(char *buf,
                                        uint16_t file_id, 
                                        uint64_t sec, 
                                        int secs,
-                                       uint64_t *hnd);
+                                       share_tuple_t *hnd);
 extern void memshr_vbd_complete_ro_request(
-                                       uint64_t hnd,
+                                       share_tuple_t hnd,
                                        uint16_t file_id, 
                                        uint64_t sec, 
                                        int secs);