diff options
author | David Hildenbrand <david@redhat.com> | 2021-04-29 13:27:04 +0200 |
---|---|---|
committer | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2021-05-13 18:21:13 +0100 |
commit | cc61c703b6a8b9dfdfb92d5f3fa1961f6d232926 (patch) | |
tree | c1b98f0c29c97c9457c5e357e94e2aea220d26fb /migration | |
parent | dcdc460767ed0a650e06ff256fa2a52ff1b57047 (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.c | 30 |
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 = { |