A new "share" property can be used with the "memory-file" backend to
map memory with MAP_SHARED instead of MAP_PRIVATE.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
backends/hostmem-file.c | 26 +++++++++++++++++++++++++-
exec.c | 17 +++++++++--------
include/exec/memory.h | 2 ++
include/exec/ram_addr.h | 2 +-
memory.c | 3 ++-
numa.c | 2 +-
6 files changed, 40 insertions(+), 12 deletions(-)
diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
index 6199a27..1b65445 100644
--- a/backends/hostmem-file.c
+++ b/backends/hostmem-file.c
@@ -28,6 +28,8 @@ typedef struct HostMemoryBackendFile HostMemoryBackendFile;
struct HostMemoryBackendFile {
HostMemoryBackend parent_obj;
+
+ bool share;
char *mem_path;
};
@@ -51,7 +53,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error
**errp)
backend->force_prealloc = mem_prealloc;
memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
object_get_canonical_path(OBJECT(backend)),
- backend->size,
+ backend->size, fb->share,
fb->mem_path, errp);
}
#endif
@@ -87,9 +89,31 @@ static void set_mem_path(Object *o, const char *str, Error
**errp)
fb->mem_path = g_strdup(str);
}
+static bool file_memory_backend_get_share(Object *o, Error **errp)
+{
+ HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
+
+ return fb->share;
+}
+
+static void file_memory_backend_set_share(Object *o, bool value, Error **errp)
+{
+ HostMemoryBackend *backend = MEMORY_BACKEND(o);
+ HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
+
+ if (memory_region_size(&backend->mr)) {
+ error_setg(errp, "cannot change property value");
+ return;
+ }
+ fb->share = value;
+}
+
static void
file_backend_instance_init(Object *o)
{
+ object_property_add_bool(o, "share",
+ file_memory_backend_get_share,
+ file_memory_backend_set_share, NULL);
object_property_add_str(o, "mem-path", get_mem_path,
set_mem_path, NULL);
}
diff --git a/exec.c b/exec.c
index 312db25..ecef8a4 100644
--- a/exec.c
+++ b/exec.c
@@ -74,6 +74,9 @@ static MemoryRegion io_mem_unassigned;
/* RAM is pre-allocated and passed into qemu_ram_alloc_from_ptr */
#define RAM_PREALLOC (1 << 0)
+/* RAM is mmap-ed with MAP_SHARED */
+#define RAM_SHARED (1 << 1)
+
#endif
struct CPUTailQ cpus = QTAILQ_HEAD_INITIALIZER(cpus);
@@ -1071,7 +1074,9 @@ static void *file_ram_alloc(RAMBlock *block,
if (ftruncate(fd, memory))
perror("ftruncate");
- area = mmap(0, memory, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+ area = mmap(0, memory, PROT_READ | PROT_WRITE,
+ (block->flags & RAM_SHARED ? MAP_SHARED : MAP_PRIVATE),
+ fd, 0);
if (area == MAP_FAILED) {
error_setg_errno(errp, errno, "unable to map backing store for
hugepages");
close(fd);
@@ -1260,7 +1265,7 @@ static ram_addr_t ram_block_add(RAMBlock *new_block)
#ifdef __linux__
ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
- const char *mem_path,
+ bool share, const char *mem_path,
Error **errp)
{
RAMBlock *new_block;
@@ -1285,6 +1290,7 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size,
MemoryRegion *mr,
new_block = g_malloc0(sizeof(*new_block));
new_block->mr = mr;
new_block->length = size;
+ new_block->flags = share ? RAM_SHARED : 0;
new_block->host = file_ram_alloc(new_block, size,
mem_path, errp);
if (!new_block->host) {
@@ -1387,12 +1393,7 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length)
flags = MAP_FIXED;
munmap(vaddr, length);
if (block->fd >= 0) {
-#ifdef MAP_POPULATE
- flags |= mem_prealloc ? MAP_POPULATE | MAP_SHARED :
- MAP_PRIVATE;
-#else
- flags |= MAP_PRIVATE;
-#endif
+ flags |= (block->flags & RAM_SHARED ? MAP_SHARED :
MAP_PRIVATE);
area = mmap(vaddr, length, PROT_READ | PROT_WRITE,
flags, block->fd, offset);
} else {
diff --git a/include/exec/memory.h b/include/exec/memory.h
index d7a47c4..c60f66d 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -321,6 +321,7 @@ void memory_region_init_ram(MemoryRegion *mr,
* @owner: the object that tracks the region's reference count
* @name: the name of the region.
* @size: size of the region.
+ * @share: %true if memory must be mmaped with the MAP_SHARED flag
* @path: the path in which to allocate the RAM.
* @errp: pointer to Error*, to store an error if it happens.
*/
@@ -328,6 +329,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr,
struct Object *owner,
const char *name,
uint64_t size,
+ bool share,
const char *path,
Error **errp);
#endif
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index d352f60..5f8d30d 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -23,7 +23,7 @@
#include "hw/xen/xen.h"
ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
- const char *mem_path, Error **errp);
+ bool share, const char *mem_path, Error
**errp);
ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
MemoryRegion *mr);
ram_addr_t qemu_ram_alloc(ram_addr_t size, MemoryRegion *mr);
diff --git a/memory.c b/memory.c
index 6909c16..b071cbf 100644
--- a/memory.c
+++ b/memory.c
@@ -1025,6 +1025,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr,
struct Object *owner,
const char *name,
uint64_t size,
+ bool share,
const char *path,
Error **errp)
{
@@ -1032,7 +1033,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr,
mr->ram = true;
mr->terminates = true;
mr->destructor = memory_region_destructor_ram;
- mr->ram_addr = qemu_ram_alloc_from_file(size, mr, path, errp);
+ mr->ram_addr = qemu_ram_alloc_from_file(size, mr, share, path, errp);
}
#endif
diff --git a/numa.c b/numa.c
index bf22848..4a1ba0c 100644
--- a/numa.c
+++ b/numa.c
@@ -231,7 +231,7 @@ static void allocate_system_memory_nonnuma(MemoryRegion
*mr, Object *owner,
if (mem_path) {
#ifdef __linux__
Error *err = NULL;
- memory_region_init_ram_from_file(mr, owner, name, ram_size,
+ memory_region_init_ram_from_file(mr, owner, name, ram_size, false,
mem_path, &err);
/* Legacy behavior: if allocation failed, fall back to
--
1.8.5.3
