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[PATCH v5 06/10] migration/ram: Discard RAM when growing RAM blocks afte
From: |
David Hildenbrand |
Subject: |
[PATCH v5 06/10] migration/ram: Discard RAM when growing RAM blocks after ram_postcopy_incoming_init() |
Date: |
Thu, 29 Apr 2021 13:27:04 +0200 |
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>
---
migration/ram.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/migration/ram.c b/migration/ram.c
index 195fabbab0..693851d7a0 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -4142,6 +4142,7 @@ 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;
@@ -4162,6 +4163,35 @@ 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 = {
--
2.30.2
- [PATCH v5 00/10] numa/exec/migration: Fix resizing RAM blocks while migrating, David Hildenbrand, 2021/04/29
- [PATCH v5 01/10] util: vfio-helpers: Factor out and fix processing of existing ram blocks, David Hildenbrand, 2021/04/29
- [PATCH v5 02/10] numa: Teach ram block notifiers about resizeable ram blocks, David Hildenbrand, 2021/04/29
- [PATCH v5 03/10] numa: Make all callbacks of ram block notifiers optional, David Hildenbrand, 2021/04/29
- [PATCH v5 04/10] migration/ram: Handle RAM block resizes during precopy, David Hildenbrand, 2021/04/29
- [PATCH v5 05/10] exec: Relax range check in ram_block_discard_range(), David Hildenbrand, 2021/04/29
- [PATCH v5 06/10] migration/ram: Discard RAM when growing RAM blocks after ram_postcopy_incoming_init(),
David Hildenbrand <=
- [PATCH v5 07/10] migration/ram: Simplify host page handling in ram_load_postcopy(), David Hildenbrand, 2021/04/29
- [PATCH v5 08/10] migration/ram: Handle RAM block resizes during postcopy, David Hildenbrand, 2021/04/29
- [PATCH v5 09/10] migration/multifd: Print used_length of memory block, David Hildenbrand, 2021/04/29
- [PATCH v5 10/10] migration/ram: Use offset_in_ramblock() in range checks, David Hildenbrand, 2021/04/29