Introduce qemu_put_ram_ptr

This function allows to unlock a ram_ptr give by qemu_get_ram_ptr. After
a call to qemu_put_ram_ptr, the pointer may be unmap from QEMU when
used with Xen.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Alexander Graf <agraf@suse.de>

4 files changed, 72 insertions, 3 deletions

diff --git a/cpu-common.h b/cpu-common.h
index 6410cccda5..151c32c1f2 100644
--- a/cpu-common.h
+++ b/cpu-common.h
@@ -67,6 +67,7 @@ void *qemu_get_ram_ptr(ram_addr_t addr);
 /* Same but slower, to use for migration, where the order of
  * RAMBlocks must not change. */
 void *qemu_safe_ram_ptr(ram_addr_t addr);
+void qemu_put_ram_ptr(void *addr);
 /* This should not be used by devices.  */
 int qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr);
 ram_addr_t qemu_ram_addr_from_host_nofail(void *ptr);
diff --git a/exec.c b/exec.c
index 8c81cffaa7..a6df2d6139 100644
--- a/exec.c
+++ b/exec.c
@@ -3110,6 +3110,27 @@ void *qemu_safe_ram_ptr(ram_addr_t addr)
     return NULL;
 }
 
+void qemu_put_ram_ptr(void *addr)
+{
+    trace_qemu_put_ram_ptr(addr);
+
+    if (xen_mapcache_enabled()) {
+        RAMBlock *block;
+
+        QLIST_FOREACH(block, &ram_list.blocks, next) {
+            if (addr == block->host) {
+                break;
+            }
+        }
+        if (block && block->host) {
+            xen_unmap_block(block->host, block->length);
+            block->host = NULL;
+        } else {
+            qemu_map_cache_unlock(addr);
+        }
+    }
+}
+
 int qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
 {
     RAMBlock *block;
@@ -3825,6 +3846,7 @@ void cpu_physical_memory_rw(target_phys_addr_t addr, uint8_t *buf,
                     cpu_physical_memory_set_dirty_flags(
                         addr1, (0xff & ~CODE_DIRTY_FLAG));
                 }
+                qemu_put_ram_ptr(ptr);
             }
         } else {
             if ((pd & ~TARGET_PAGE_MASK) > IO_MEM_ROM &&
@@ -3852,9 +3874,9 @@ void cpu_physical_memory_rw(target_phys_addr_t addr, uint8_t *buf,
                 }
             } else {
                 /* RAM case */
-                ptr = qemu_get_ram_ptr(pd & TARGET_PAGE_MASK) +
-                    (addr & ~TARGET_PAGE_MASK);
-                memcpy(buf, ptr, l);
+                ptr = qemu_get_ram_ptr(pd & TARGET_PAGE_MASK);
+                memcpy(buf, ptr + (addr & ~TARGET_PAGE_MASK), l);
+                qemu_put_ram_ptr(ptr);
             }
         }
         len -= l;
@@ -3895,6 +3917,7 @@ void cpu_physical_memory_write_rom(target_phys_addr_t addr,
             /* ROM/RAM case */
             ptr = qemu_get_ram_ptr(addr1);
             memcpy(ptr, buf, l);
+            qemu_put_ram_ptr(ptr);
         }
         len -= l;
         buf += l;
@@ -4036,6 +4059,15 @@ void cpu_physical_memory_unmap(void *buffer, target_phys_addr_t len,
                 access_len -= l;
             }
         }
+        if (xen_mapcache_enabled()) {
+            uint8_t *buffer1 = buffer;
+            uint8_t *end_buffer = buffer + len;
+
+            while (buffer1 < end_buffer) {
+                qemu_put_ram_ptr(buffer1);
+                buffer1 += TARGET_PAGE_SIZE;
+            }
+        }
         return;
     }
     if (is_write) {
diff --git a/trace-events b/trace-events
index d703347d40..a00b63cefd 100644
--- a/trace-events
+++ b/trace-events
@@ -371,3 +371,6 @@ disable qemu_remap_bucket(uint64_t index) "index %#"PRIx64""
 disable qemu_map_cache_return(void* ptr) "%p"
 disable xen_map_block(uint64_t phys_addr, uint64_t size) "%#"PRIx64", size %#"PRIx64""
 disable xen_unmap_block(void* addr, unsigned long size) "%p, size %#lx"
+
+# exec.c
+disable qemu_put_ram_ptr(void* addr) "%p"
diff --git a/xen-mapcache.c b/xen-mapcache.c
index 2ca18ce3b5..349cc6221d 100644
--- a/xen-mapcache.c
+++ b/xen-mapcache.c
@@ -196,6 +196,39 @@ uint8_t *qemu_map_cache(target_phys_addr_t phys_addr, target_phys_addr_t size, u
     return mapcache->last_address_vaddr + address_offset;
 }
 
+void qemu_map_cache_unlock(void *buffer)
+{
+    MapCacheEntry *entry = NULL, *pentry = NULL;
+    MapCacheRev *reventry;
+    target_phys_addr_t paddr_index;
+    int found = 0;
+
+    QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
+        if (reventry->vaddr_req == buffer) {
+            paddr_index = reventry->paddr_index;
+            found = 1;
+            break;
+        }
+    }
+    if (!found) {
+        return;
+    }
+    QTAILQ_REMOVE(&mapcache->locked_entries, reventry, next);
+    qemu_free(reventry);
+
+    entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
+    while (entry && entry->paddr_index != paddr_index) {
+        pentry = entry;
+        entry = entry->next;
+    }
+    if (!entry) {
+        return;
+    }
+    if (entry->lock > 0) {
+        entry->lock--;
+    }
+}
+
 ram_addr_t qemu_ram_addr_from_mapcache(void *ptr)
 {
     MapCacheRev *reventry;