[RFC PATCH 5/6] savevm: Migrate RAM based on name/offset

Alex Williamson
2010-06-08T19:22:47Z

Synchronize RAM blocks with the target and migrate using name/offset
pairs. This ensures both source and target have the same view of
RAM and that we get the right bits into the right slot.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

arch_init.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++++------
vl.c | 2 +
2 files changed, 93 insertions(+), 12 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 6103461..8ba92ec 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -113,20 +113,29 @@ static int ram_save_block(QEMUFile *f)

while (addr < total_ram) {
if (cpu_physical_memory_get_dirty(current_addr, MIGRATION_DIRTY_FLAG)) {
+ RAMBlock *block;
+ ram_addr_t offset;
uint8_t *p;

cpu_physical_memory_reset_dirty(current_addr,
current_addr + TARGET_PAGE_SIZE,
MIGRATION_DIRTY_FLAG);

- p = qemu_get_ram_ptr(current_addr);
+ QLIST_FOREACH(block, &ram.blocks, next) {
+ if (current_addr - block->offset < block->length)
+ break;
+ }
+ offset = current_addr - block->offset;
+ p = block->host + offset;

if (is_dup_page(p, *p)) {
- qemu_put_be64(f, current_addr | RAM_SAVE_FLAG_COMPRESS);
+ qemu_put_be64(f, offset | RAM_SAVE_FLAG_COMPRESS);
+ qemu_put_buffer(f, (uint8_t *)block->name, sizeof(block->name));
qemu_put_byte(f, *p);
bytes_sent = 1;
} else {
- qemu_put_be64(f, current_addr | RAM_SAVE_FLAG_PAGE);
+ qemu_put_be64(f, offset | RAM_SAVE_FLAG_PAGE);
+ qemu_put_buffer(f, (uint8_t *)block->name, sizeof(block->name));
qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
bytes_sent = TARGET_PAGE_SIZE;
}
@@ -196,6 +205,7 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
}

if (stage == 1) {
+ RAMBlock *block;
uint64_t total_ram = ram_bytes_total();
bytes_transferred = 0;

@@ -210,6 +220,11 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
cpu_physical_memory_set_dirty_tracking(1);

qemu_put_be64(f, total_ram | RAM_SAVE_FLAG_MEM_SIZE);
+
+ QLIST_FOREACH(block, &ram.blocks, next) {
+ qemu_put_buffer(f, (uint8_t *)block->name, sizeof(block->name));
+ qemu_put_be64(f, block->length);
+ }
}

bytes_transferred_last = bytes_transferred;
@@ -257,7 +272,7 @@ int ram_load(QEMUFile *f, void *opaque, int version_id)
ram_addr_t addr;
int flags;

- if (version_id != 3) {
+ if (version_id < 3) {
return -EINVAL;
}

@@ -268,23 +283,89 @@ int ram_load(QEMUFile *f, void *opaque, int version_id)
addr &= TARGET_PAGE_MASK;

if (flags & RAM_SAVE_FLAG_MEM_SIZE) {
- if (addr != ram_bytes_total()) {
- return -EINVAL;
+ if (version_id == 3) {
+ if (addr != ram_bytes_total()) {
+ return -EINVAL;
+ }
+ } else {
+ /* Synchronize RAM block list */
+ char name[64];
+ ram_addr_t length;
+ ram_addr_t total_ram_bytes = addr;
+
+ while (total_ram_bytes) {
+ RAMBlock *block;
+ qemu_get_buffer(f, (uint8_t *)name, sizeof(name));
+ length = qemu_get_be64(f);
+
+ QLIST_FOREACH(block, &ram.blocks, next) {
+ if (!strncmp(name, block->name, sizeof(name))) {
+ if (block->length != length)
+ return -EINVAL;
+ break;
+ }
+ }
+
+ if (!block) {
+ if (!qemu_ram_alloc(name, length))
+ return -ENOMEM;
+ }
+
+ total_ram_bytes -= length;
+ }
}
}

if (flags & RAM_SAVE_FLAG_COMPRESS) {
- uint8_t ch = qemu_get_byte(f);
- memset(qemu_get_ram_ptr(addr), ch, TARGET_PAGE_SIZE);
+ void *host;
+ uint8_t ch;
+
+ if (version_id == 3) {
+ host = qemu_get_ram_ptr(addr);
+ } else {
+ RAMBlock *block;
+ char name[64];
+
+ qemu_get_buffer(f, (uint8_t *)name, sizeof(name));
+
+ QLIST_FOREACH(block, &ram.blocks, next) {
+ if (!strncmp(name, block->name, sizeof(name)))
+ break;
+ }
+ if (!block)
+ return -EINVAL;
+
+ host = block->host + addr;
+ }
+ ch = qemu_get_byte(f);
+ memset(host, ch, TARGET_PAGE_SIZE);
#ifndef _WIN32
if (ch == 0 &&
(!kvm_enabled() || kvm_has_sync_mmu())) {
- madvise(qemu_get_ram_ptr(addr), TARGET_PAGE_SIZE,
- MADV_DONTNEED);
+ madvise(host, TARGET_PAGE_SIZE, MADV_DONTNEED);
}
#endif
} else if (flags & RAM_SAVE_FLAG_PAGE) {
- qemu_get_buffer(f, qemu_get_ram_ptr(addr), TARGET_PAGE_SIZE);
+ void *host;
+
+ if (version_id == 3) {
+ host = qemu_get_ram_ptr(addr);
+ } else {
+ RAMBlock *block;
+ char name[64];
+
+ qemu_get_buffer(f, (uint8_t *)name, sizeof(name));
+
+ QLIST_FOREACH(block, &ram.blocks, next) {
+ if (!strncmp(name, block->name, sizeof(name)))
+ break;
+ }
+ if (!block)
+ return -EINVAL;
+
+ host = block->host + addr;
+ }
+ qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
}
if (qemu_file_has_error(f)) {
return -EIO;
diff --git a/vl.c b/vl.c
index 9e9c176..a871895 100644
--- a/vl.c
+++ b/vl.c
@@ -3731,7 +3731,7 @@ int main(int argc, char **argv, char **envp)
if (qemu_opts_foreach(&qemu_drive_opts, drive_init_func, machine, 1) != 0)
exit(1);

- register_savevm_live("ram", 0, 3, NULL, ram_save_live, NULL,
+ register_savevm_live("ram", 0, 4, NULL, ram_save_live, NULL,
ram_load, NULL);

if (nb_numa_nodes > 0) {