Save the memfd for ramblocks in CPR state, along with a name that
uniquely identifies it. The block's idstr is not yet set, so it
cannot be used for this purpose. Find the saved memfd in new QEMU when
creating a block. If size of a resizable block is larger in new QEMU,
extend it via the file_ram_alloc truncate parameter, and the extra space
will be usable after a guest reset.
Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
Reviewed-by: Peter Xu <pet...@redhat.com>
---
system/physmem.c | 44 +++++++++++++++++++++++++++++++++++++++-----
1 file changed, 39 insertions(+), 5 deletions(-)
diff --git a/system/physmem.c b/system/physmem.c
index cb80ce3..67c9db9 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -70,6 +70,7 @@
#include "qemu/pmem.h"
+#include "migration/cpr.h"
#include "migration/vmstate.h"
#include "qemu/range.h"
@@ -1661,6 +1662,18 @@ void qemu_ram_unset_idstr(RAMBlock *block)
}
}
+static char *cpr_name(MemoryRegion *mr)
+{
+ const char *mr_name = memory_region_name(mr);
+ g_autofree char *id = mr->dev ? qdev_get_dev_path(mr->dev) : NULL;
+
+ if (id) {
+ return g_strdup_printf("%s/%s", id, mr_name);
+ } else {
+ return g_strdup(mr_name);
+ }
+}
+
size_t qemu_ram_pagesize(RAMBlock *rb)
{
return rb->page_size;
@@ -2080,15 +2093,25 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size,
MemoryRegion *mr,
* shared with another process if CPR is being used. Use memfd if available
* because it has no size limits, else use POSIX shm.
*/
-static int qemu_ram_get_shared_fd(const char *name, Error **errp)
+static int qemu_ram_get_shared_fd(const char *name, bool *reused, Error **errp)
{
- int fd;
+ int fd = cpr_find_fd(name, 0);
+
+ if (fd >= 0) {
+ *reused = true;
+ return fd;
+ }
if (qemu_memfd_check(0)) {
fd = qemu_memfd_create(name, 0, 0, 0, 0, errp);
} else {
fd = qemu_shm_alloc(0, errp);
}
+
+ if (fd >= 0) {
+ cpr_save_fd(name, 0, fd);
+ }
+ *reused = false;
return fd;
}
#endif
@@ -2118,8 +2141,9 @@ RAMBlock *qemu_ram_alloc_internal(ram_addr_t size,
ram_addr_t max_size,
ram_flags |= RAM_SHARED;
}
if (ram_flags & RAM_SHARED) {
- const char *name = memory_region_name(mr);
- int fd = qemu_ram_get_shared_fd(name, errp);
+ bool reused;
+ g_autofree char *name = cpr_name(mr);
+ int fd = qemu_ram_get_shared_fd(name, &reused, errp);
if (fd < 0) {
return NULL;
@@ -2133,9 +2157,14 @@ RAMBlock *qemu_ram_alloc_internal(ram_addr_t size,
ram_addr_t max_size,
* fd is not supported, but previous QEMU versions that called
* qemu_anon_ram_alloc for anonymous shared memory could have
* succeeded. Quietly fail and fall back.
+ *
+ * After cpr-transfer, new QEMU could create a memory region
+ * with a larger max size than old, so pass reused to grow the
+ * region if necessary. The extra space will be usable after a
+ * guest reset.
*/
new_block = qemu_ram_alloc_from_fd(size, max_size, resized, mr,
- ram_flags, fd, 0, false, NULL);
+ ram_flags, fd, 0, reused, NULL);
if (new_block) {
trace_qemu_ram_alloc_shared(name, new_block->used_length,
new_block->max_length, fd,
@@ -2143,6 +2172,7 @@ RAMBlock *qemu_ram_alloc_internal(ram_addr_t size,
ram_addr_t max_size,
return new_block;
}
+ cpr_delete_fd(name, 0);
close(fd);
/* fall back to anon allocation */
}
@@ -2221,6 +2251,8 @@ static void reclaim_ramblock(RAMBlock *block)
void qemu_ram_free(RAMBlock *block)
{
+ g_autofree char *name = NULL;
+
if (!block) {
return;
}
@@ -2231,6 +2263,8 @@ void qemu_ram_free(RAMBlock *block)
}
qemu_mutex_lock_ramlist();
+ name = cpr_name(block->mr);
+ cpr_delete_fd(name, 0);
QLIST_REMOVE_RCU(block, next);
ram_list.mru_block = NULL;
/* Write list before version */
--
1.8.3.1
