migrate_ignore_shared() is an optimization that avoids copying memory
that is visible and can be mapped on the target. However, a
memory-backend-ram or a memory-backend-memfd block with the RAM_SHARED
flag set is not migrated when migrate_ignore_shared() is true. This is
wrong, because the block has no named backing store, and its contents will
be lost. To fix, ignore shared memory iff it is a named file. Define a
new flag RAM_NAMED_FILE to distinguish this case.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <
1686151116-253260-1-git-send-email-steven.sistare@oracle.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
ram_flags = backend->share ? RAM_SHARED : 0;
ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
ram_flags |= fb->is_pmem ? RAM_PMEM : 0;
+ ram_flags |= RAM_NAMED_FILE;
memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), name,
backend->size, fb->align, ram_flags,
fb->mem_path, fb->offset, fb->readonly,
bool qemu_ram_is_migratable(RAMBlock *rb);
void qemu_ram_set_migratable(RAMBlock *rb);
void qemu_ram_unset_migratable(RAMBlock *rb);
+bool qemu_ram_is_named_file(RAMBlock *rb);
int qemu_ram_get_fd(RAMBlock *rb);
size_t qemu_ram_pagesize(RAMBlock *block);
/* RAM that isn't accessible through normal means. */
#define RAM_PROTECTED (1 << 8)
+/* RAM is an mmap-ed named file */
+#define RAM_NAMED_FILE (1 << 9)
+
static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
IOMMUNotifierFlag flags,
hwaddr start, hwaddr end,
bool ramblock_is_ignored(RAMBlock *block)
{
return !qemu_ram_is_migratable(block) ||
- (migrate_ignore_shared() && qemu_ram_is_shared(block));
+ (migrate_ignore_shared() && qemu_ram_is_shared(block)
+ && qemu_ram_is_named_file(block));
}
#undef RAMBLOCK_FOREACH
# block devices (and thus take locks) immediately at the end of
# migration. (since 3.0)
#
-# @x-ignore-shared: If enabled, QEMU will not migrate shared memory
-# (since 4.0)
+# @x-ignore-shared: If enabled, QEMU will not migrate shared memory that is
+# accessible on the destination machine. (since 4.0)
#
# @validate-uuid: Send the UUID of the source to allow the destination
# to ensure it is the same. (since 4.2)
rb->flags &= ~RAM_MIGRATABLE;
}
+bool qemu_ram_is_named_file(RAMBlock *rb)
+{
+ return rb->flags & RAM_NAMED_FILE;
+}
+
int qemu_ram_get_fd(RAMBlock *rb)
{
return rb->fd;
/* Just support these ram flags by now. */
assert((ram_flags & ~(RAM_SHARED | RAM_PMEM | RAM_NORESERVE |
- RAM_PROTECTED)) == 0);
+ RAM_PROTECTED | RAM_NAMED_FILE)) == 0);
if (xen_enabled()) {
error_setg(errp, "-mem-path not supported with Xen");