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[PULL 18/20] migration/postcopy: Detect file system on dest host
From: |
Juan Quintela |
Subject: |
[PULL 18/20] migration/postcopy: Detect file system on dest host |
Date: |
Thu, 20 Apr 2023 15:17:49 +0200 |
From: Peter Xu <peterx@redhat.com>
Postcopy requires the memory support userfaultfd to work. Right now we
check it but it's a bit too late (when switching to postcopy migration).
Do that early right at enabling of postcopy.
Note that this is still only a best effort because ramblocks can be
dynamically created. We can add check in hostmem creations and fail if
postcopy enabled, but maybe that's too aggressive.
Still, we have chance to fail the most obvious where we know there's an
existing unsupported ramblock.
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
migration/postcopy-ram.c | 34 ++++++++++++++++++++++++++++++----
1 file changed, 30 insertions(+), 4 deletions(-)
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 7d24dac397..d7b48dd920 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -36,6 +36,7 @@
#include "yank_functions.h"
#include "tls.h"
#include "qemu/userfaultfd.h"
+#include "qemu/mmap-alloc.h"
/* Arbitrary limit on size of each discard command,
* keeps them around ~200 bytes
@@ -336,11 +337,12 @@ static bool ufd_check_and_apply(int ufd,
MigrationIncomingState *mis)
/* Callback from postcopy_ram_supported_by_host block iterator.
*/
-static int test_ramblock_postcopiable(RAMBlock *rb, void *opaque)
+static int test_ramblock_postcopiable(RAMBlock *rb)
{
const char *block_name = qemu_ram_get_idstr(rb);
ram_addr_t length = qemu_ram_get_used_length(rb);
size_t pagesize = qemu_ram_pagesize(rb);
+ QemuFsType fs;
if (length % pagesize) {
error_report("Postcopy requires RAM blocks to be a page size multiple,"
@@ -348,6 +350,15 @@ static int test_ramblock_postcopiable(RAMBlock *rb, void
*opaque)
"page size of 0x%zx", block_name, length, pagesize);
return 1;
}
+
+ if (rb->fd >= 0) {
+ fs = qemu_fd_getfs(rb->fd);
+ if (fs != QEMU_FS_TYPE_TMPFS && fs != QEMU_FS_TYPE_HUGETLBFS) {
+ error_report("Host backend files need to be TMPFS or HUGETLBFS
only");
+ return 1;
+ }
+ }
+
return 0;
}
@@ -366,6 +377,7 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState
*mis)
struct uffdio_range range_struct;
uint64_t feature_mask;
Error *local_err = NULL;
+ RAMBlock *block;
if (qemu_target_page_size() > pagesize) {
error_report("Target page size bigger than host page size");
@@ -390,9 +402,23 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState
*mis)
goto out;
}
- /* We don't support postcopy with shared RAM yet */
- if (foreach_not_ignored_block(test_ramblock_postcopiable, NULL)) {
- goto out;
+ /*
+ * We don't support postcopy with some type of ramblocks.
+ *
+ * NOTE: we explicitly ignored ramblock_is_ignored() instead we checked
+ * all possible ramblocks. This is because this function can be called
+ * when creating the migration object, during the phase RAM_MIGRATABLE
+ * is not even properly set for all the ramblocks.
+ *
+ * A side effect of this is we'll also check against RAM_SHARED
+ * ramblocks even if migrate_ignore_shared() is set (in which case
+ * we'll never migrate RAM_SHARED at all), but normally this shouldn't
+ * affect in reality, or we can revisit.
+ */
+ RAMBLOCK_FOREACH(block) {
+ if (test_ramblock_postcopiable(block)) {
+ goto out;
+ }
}
/*
--
2.39.2
- [PULL 06/20] migration: Make dirty_sync_missed_zero_copy atomic, (continued)
- [PULL 06/20] migration: Make dirty_sync_missed_zero_copy atomic, Juan Quintela, 2023/04/20
- [PULL 11/20] migration: Make dirty_pages_rate atomic, Juan Quintela, 2023/04/20
- [PULL 04/20] migration: Update atomic stats out of the mutex, Juan Quintela, 2023/04/20
- [PULL 03/20] migration: Merge ram_counters and ram_atomic_counters, Juan Quintela, 2023/04/20
- [PULL 05/20] migration: Make multifd_bytes atomic, Juan Quintela, 2023/04/20
- [PULL 07/20] migration: Make precopy_bytes atomic, Juan Quintela, 2023/04/20
- [PULL 13/20] migration: Rename duplicate to zero_pages, Juan Quintela, 2023/04/20
- [PULL 08/20] migration: Make downtime_bytes atomic, Juan Quintela, 2023/04/20
- [PULL 16/20] util/mmap-alloc: qemu_fd_getfs(), Juan Quintela, 2023/04/20
- [PULL 17/20] vl.c: Create late backends before migration object, Juan Quintela, 2023/04/20
- [PULL 18/20] migration/postcopy: Detect file system on dest host,
Juan Quintela <=
- [PULL 19/20] migration: rename enabled_capabilities to capabilities, Juan Quintela, 2023/04/20
- [PULL 20/20] migration: Pass migrate_caps_check() the old and new caps, Juan Quintela, 2023/04/20
- [PULL 02/20] postcopy-ram: do not use qatomic_mb_read, Juan Quintela, 2023/04/20
- [PULL 14/20] migration: Rename normal to normal_pages, Juan Quintela, 2023/04/20
- [PULL 10/20] migration: Make postcopy_requests atomic, Juan Quintela, 2023/04/20
- [PULL 15/20] migration: Handle block device inactivation failures better, Juan Quintela, 2023/04/20
- Re: [PULL 00/20] Migration 20230420 patches, Richard Henderson, 2023/04/22