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authorDavid Hildenbrand <david@redhat.com>2021-04-29 13:27:04 +0200
committerDr. David Alan Gilbert <dgilbert@redhat.com>2021-05-13 18:21:13 +0100
commitcc61c703b6a8b9dfdfb92d5f3fa1961f6d232926 (patch)
treec1b98f0c29c97c9457c5e357e94e2aea220d26fb /migration
parentdcdc460767ed0a650e06ff256fa2a52ff1b57047 (diff)
migration/ram: Discard RAM when growing RAM blocks after ram_postcopy_incoming_init()
In case we grow our RAM after ram_postcopy_incoming_init() (e.g., when synchronizing the RAM block state with the migration source), the resized part would not get discarded. Let's perform that when being notified about a resize while postcopy has been advised, but is not listening yet. With precopy, the process is as following: 1. VM created - RAM blocks are created 2. Incomming migration started - Postcopy is advised - All pages in RAM blocks are discarded 3. Precopy starts - RAM blocks are resized to match the size on the migration source. - RAM pages from precopy stream are loaded - Uffd handler is registered, postcopy starts listening 4. Guest started, postcopy running - Pagefaults get resolved, pages get placed Reviewed-by: Peter Xu <peterx@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Message-Id: <20210429112708.12291-7-david@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Diffstat (limited to 'migration')
-rw-r--r--migration/ram.c30
1 files changed, 30 insertions, 0 deletions
diff --git a/migration/ram.c b/migration/ram.c
index 77922c445e..e1d081d334 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -4099,6 +4099,7 @@ static SaveVMHandlers savevm_ram_handlers = {
static void ram_mig_ram_block_resized(RAMBlockNotifier *n, void *host,
size_t old_size, size_t new_size)
{
+ PostcopyState ps = postcopy_state_get();
ram_addr_t offset;
RAMBlock *rb = qemu_ram_block_from_host(host, false, &offset);
Error *err = NULL;
@@ -4119,6 +4120,35 @@ static void ram_mig_ram_block_resized(RAMBlockNotifier *n, void *host,
error_free(err);
migration_cancel();
}
+
+ switch (ps) {
+ case POSTCOPY_INCOMING_ADVISE:
+ /*
+ * Update what ram_postcopy_incoming_init()->init_range() does at the
+ * time postcopy was advised. Syncing RAM blocks with the source will
+ * result in RAM resizes.
+ */
+ if (old_size < new_size) {
+ if (ram_discard_range(rb->idstr, old_size, new_size - old_size)) {
+ error_report("RAM block '%s' discard of resized RAM failed",
+ rb->idstr);
+ }
+ }
+ break;
+ case POSTCOPY_INCOMING_NONE:
+ case POSTCOPY_INCOMING_RUNNING:
+ case POSTCOPY_INCOMING_END:
+ /*
+ * Once our guest is running, postcopy does no longer care about
+ * resizes. When growing, the new memory was not available on the
+ * source, no handler needed.
+ */
+ break;
+ default:
+ error_report("RAM block '%s' resized during postcopy state: %d",
+ rb->idstr, ps);
+ exit(-1);
+ }
}
static RAMBlockNotifier ram_mig_ram_notifier = {