Merge tag 'migration-20250129-pull-request' of https://gitlab.com/farosas/qemu into staging

Migration pull request

- Purge of ram_save_target_page_legacy
- Cleanups to postcopy, json writer, migration states
- New migration mode cpr-transfer
- Fix for a -Werror=maybe-uninitialized instance in savevm

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* tag 'migration-20250129-pull-request' of https://gitlab.com/farosas/qemu: (42 commits)
  migration: refactor ram_save_target_page functions
  migration: Trivial cleanup on JSON writer of vmstate_save()
  migration: Merge precopy/postcopy on switchover start
  migration: Always set DEVICE state
  migration: Cleanup qemu_savevm_state_complete_precopy()
  migration: Unwrap qemu_savevm_state_complete_precopy() in postcopy
  migration: Notify COMPLETE once for postcopy
  migration: Take BQL slightly longer in postcopy_start()
  migration: Drop cached migration state in migration_maybe_pause()
  migration: Adjust locking in migration_maybe_pause()
  migration: Adjust postcopy bandwidth during switchover
  migration: Synchronize all CPU states only for non-iterable dump
  migration: Drop inactivate_disk param in qemu_savevm_state_complete*
  migration: Avoid two src-downtime-end tracepoints for postcopy
  migration: Optimize postcopy on downtime by avoiding JSON writer
  migration: Do not construct JSON description if suppressed
  migration: Remove postcopy implications in should_send_vmdesc()
  migration: cpr-transfer documentation
  migration-test: cpr-transfer
  tests/qtest: assert qmp connected
  ...

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

2 files changed, 19 insertions, 4 deletions

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 3ee1901b52..9f73b59867 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -246,6 +246,16 @@ typedef struct IOMMUTLBEvent {
 /* RAM can be private that has kvm guest memfd backend */
 #define RAM_GUEST_MEMFD   (1 << 12)
 
+/*
+ * In RAMBlock creation functions, if MAP_SHARED is 0 in the flags parameter,
+ * the implementation may still create a shared mapping if other conditions
+ * require it.  Callers who specifically want a private mapping, eg objects
+ * specified by the user, must pass RAM_PRIVATE.
+ * After RAMBlock creation, MAP_SHARED in the block's flags indicates whether
+ * the block is shared or private, and MAP_PRIVATE is omitted.
+ */
+#define RAM_PRIVATE (1 << 13)
+
 static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
                                        IOMMUNotifierFlag flags,
                                        hwaddr start, hwaddr end,
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index ff157c1f42..94bb3ccbe4 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -111,23 +111,30 @@ long qemu_maxrampagesize(void);
  *
  * Parameters:
  *  @size: the size in bytes of the ram block
+ *  @max_size: the maximum size of the block after resizing
  *  @mr: the memory region where the ram block is
+ *  @resized: callback after calls to qemu_ram_resize
  *  @ram_flags: RamBlock flags. Supported flags: RAM_SHARED, RAM_PMEM,
  *              RAM_NORESERVE, RAM_PROTECTED, RAM_NAMED_FILE, RAM_READONLY,
  *              RAM_READONLY_FD, RAM_GUEST_MEMFD
  *  @mem_path or @fd: specify the backing file or device
  *  @offset: Offset into target file
+ *  @grow: extend file if necessary (but an empty file is always extended).
  *  @errp: pointer to Error*, to store an error if it happens
  *
  * Return:
  *  On success, return a pointer to the ram block.
  *  On failure, return NULL.
  */
+typedef void (*qemu_ram_resize_cb)(const char *, uint64_t length, void *host);
+
 RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
                                    uint32_t ram_flags, const char *mem_path,
                                    off_t offset, Error **errp);
-RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
+RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, ram_addr_t max_size,
+                                 qemu_ram_resize_cb resized, MemoryRegion *mr,
                                  uint32_t ram_flags, int fd, off_t offset,
+                                 bool grow,
                                  Error **errp);
 
 RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
@@ -135,9 +142,7 @@ RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
 RAMBlock *qemu_ram_alloc(ram_addr_t size, uint32_t ram_flags, MemoryRegion *mr,
                          Error **errp);
 RAMBlock *qemu_ram_alloc_resizeable(ram_addr_t size, ram_addr_t max_size,
-                                    void (*resized)(const char*,
-                                                    uint64_t length,
-                                                    void *host),
+                                    qemu_ram_resize_cb resized,
                                     MemoryRegion *mr, Error **errp);
 void qemu_ram_free(RAMBlock *block);