[Xen-devel] [PATCH V15 12/18] Introduce qemu_put_ram_ptr

[<anthony.perard@xxxxxxxxxx>]

From: Anthony PERARD <anthony.perard@xxxxxxxxxx>

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@xxxxxxxxxx>
Acked-by: Alexander Graf <agraf@xxxxxxx>
---
 cpu-common.h   |    1 +
 exec.c         |   38 +++++++++++++++++++++++++++++++++++---
 trace-events   |    3 +++
 xen-mapcache.c |   33 +++++++++++++++++++++++++++++++++
 4 files changed, 72 insertions(+), 3 deletions(-)

diff --git a/cpu-common.h b/cpu-common.h
index 96c02ae..1d4fdbf 100644
--- a/cpu-common.h
+++ b/cpu-common.h
@@ -56,6 +56,7 @@ 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 19707c5..063d2f6 100644
--- a/exec.c
+++ b/exec.c
@@ -3100,6 +3100,27 @@ 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;
@@ -3815,6 +3836,7 @@ 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 &&
@@ -3842,9 +3864,9 @@ 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;
@@ -3885,6 +3907,7 @@ 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;
@@ -4026,6 +4049,15 @@ 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 d703347..a00b63c 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 2ca18ce..349cc62 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;
-- 
1.7.2.5


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