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exec: split length -> used_length/max_length
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This patch allows us to distinguish between two
length values for each block:
    max_length - length of memory block that was allocated
    used_length - length of block used by QEMU/guest

Currently, we set used_length - max_length, unconditionally.
Follow-up patches allow used_length <= max_length.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
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@mstsirkin
mstsirkin committed Jan 8, 2015
1 parent c8d6f66 commit 9b8424d
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Showing 3 changed files with 40 additions and 34 deletions.
19 changes: 10 additions & 9 deletions arch_init.c
View file
Expand Up @@ -522,7 +522,7 @@ static void migration_bitmap_sync(void)
address_space_sync_dirty_bitmap(&address_space_memory);

QTAILQ_FOREACH(block, &ram_list.blocks, next) {
migration_bitmap_sync_range(block->mr->ram_addr, block->length);
migration_bitmap_sync_range(block->mr->ram_addr, block->used_length);
}
trace_migration_bitmap_sync_end(migration_dirty_pages
- num_dirty_pages_init);
Expand Down Expand Up @@ -668,7 +668,7 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage)
offset >= last_offset) {
break;
}
if (offset >= block->length) {
if (offset >= block->used_length) {
offset = 0;
block = QTAILQ_NEXT(block, next);
if (!block) {
Expand Down Expand Up @@ -727,7 +727,7 @@ uint64_t ram_bytes_total(void)
uint64_t total = 0;

QTAILQ_FOREACH(block, &ram_list.blocks, next)
total += block->length;
total += block->used_length;

return total;
}
Expand Down Expand Up @@ -831,7 +831,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
QTAILQ_FOREACH(block, &ram_list.blocks, next) {
uint64_t block_pages;

block_pages = block->length >> TARGET_PAGE_BITS;
block_pages = block->used_length >> TARGET_PAGE_BITS;
migration_dirty_pages += block_pages;
}

Expand All @@ -844,7 +844,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
QTAILQ_FOREACH(block, &ram_list.blocks, next) {
qemu_put_byte(f, strlen(block->idstr));
qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr));
qemu_put_be64(f, block->length);
qemu_put_be64(f, block->used_length);
}

qemu_mutex_unlock_ramlist();
Expand Down Expand Up @@ -1015,7 +1015,7 @@ static inline void *host_from_stream_offset(QEMUFile *f,
uint8_t len;

if (flags & RAM_SAVE_FLAG_CONTINUE) {
if (!block || block->length <= offset) {
if (!block || block->max_length <= offset) {
error_report("Ack, bad migration stream!");
return NULL;
}
Expand All @@ -1028,7 +1028,8 @@ static inline void *host_from_stream_offset(QEMUFile *f,
id[len] = 0;

QTAILQ_FOREACH(block, &ram_list.blocks, next) {
if (!strncmp(id, block->idstr, sizeof(id)) && block->length > offset) {
if (!strncmp(id, block->idstr, sizeof(id)) &&
block->max_length > offset) {
return memory_region_get_ram_ptr(block->mr) + offset;
}
}
Expand Down Expand Up @@ -1085,10 +1086,10 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)

QTAILQ_FOREACH(block, &ram_list.blocks, next) {
if (!strncmp(id, block->idstr, sizeof(id))) {
if (block->length != length) {
if (block->used_length != length) {
error_report("Length mismatch: %s: 0x" RAM_ADDR_FMT
" in != 0x" RAM_ADDR_FMT, id, length,
block->length);
block->used_length);
ret = -EINVAL;
}
break;
Expand Down
52 changes: 28 additions & 24 deletions exec.c
View file
Expand Up @@ -812,11 +812,11 @@ static RAMBlock *qemu_get_ram_block(ram_addr_t addr)

/* The list is protected by the iothread lock here. */
block = ram_list.mru_block;
if (block && addr - block->offset < block->length) {
if (block && addr - block->offset < block->max_length) {
goto found;
}
QTAILQ_FOREACH(block, &ram_list.blocks, next) {
if (addr - block->offset < block->length) {
if (addr - block->offset < block->max_length) {
goto found;
}
}
Expand Down Expand Up @@ -1305,13 +1305,14 @@ static ram_addr_t ram_block_add(RAMBlock *new_block, Error **errp)

/* This assumes the iothread lock is taken here too. */
qemu_mutex_lock_ramlist();
new_block->offset = find_ram_offset(new_block->length);
new_block->offset = find_ram_offset(new_block->max_length);

if (!new_block->host) {
if (xen_enabled()) {
xen_ram_alloc(new_block->offset, new_block->length, new_block->mr);
xen_ram_alloc(new_block->offset, new_block->max_length,
new_block->mr);
} else {
new_block->host = phys_mem_alloc(new_block->length,
new_block->host = phys_mem_alloc(new_block->max_length,
&new_block->mr->align);
if (!new_block->host) {
error_setg_errno(errp, errno,
Expand All @@ -1320,13 +1321,13 @@ static ram_addr_t ram_block_add(RAMBlock *new_block, Error **errp)
qemu_mutex_unlock_ramlist();
return -1;
}
memory_try_enable_merging(new_block->host, new_block->length);
memory_try_enable_merging(new_block->host, new_block->max_length);
}
}

/* Keep the list sorted from biggest to smallest block. */
QTAILQ_FOREACH(block, &ram_list.blocks, next) {
if (block->length < new_block->length) {
if (block->max_length < new_block->max_length) {
break;
}
}
Expand All @@ -1350,14 +1351,15 @@ static ram_addr_t ram_block_add(RAMBlock *new_block, Error **errp)
old_ram_size, new_ram_size);
}
}
cpu_physical_memory_set_dirty_range(new_block->offset, new_block->length);
cpu_physical_memory_set_dirty_range(new_block->offset,
new_block->used_length);

qemu_ram_setup_dump(new_block->host, new_block->length);
qemu_madvise(new_block->host, new_block->length, QEMU_MADV_HUGEPAGE);
qemu_madvise(new_block->host, new_block->length, QEMU_MADV_DONTFORK);
qemu_ram_setup_dump(new_block->host, new_block->max_length);
qemu_madvise(new_block->host, new_block->max_length, QEMU_MADV_HUGEPAGE);
qemu_madvise(new_block->host, new_block->max_length, QEMU_MADV_DONTFORK);

if (kvm_enabled()) {
kvm_setup_guest_memory(new_block->host, new_block->length);
kvm_setup_guest_memory(new_block->host, new_block->max_length);
}

return new_block->offset;
Expand Down Expand Up @@ -1391,7 +1393,8 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
size = TARGET_PAGE_ALIGN(size);
new_block = g_malloc0(sizeof(*new_block));
new_block->mr = mr;
new_block->length = size;
new_block->used_length = size;
new_block->max_length = size;
new_block->flags = share ? RAM_SHARED : 0;
new_block->host = file_ram_alloc(new_block, size,
mem_path, errp);
Expand Down Expand Up @@ -1420,7 +1423,8 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
size = TARGET_PAGE_ALIGN(size);
new_block = g_malloc0(sizeof(*new_block));
new_block->mr = mr;
new_block->length = size;
new_block->used_length = size;
new_block->max_length = max_size;
new_block->fd = -1;
new_block->host = host;
if (host) {
Expand Down Expand Up @@ -1475,11 +1479,11 @@ void qemu_ram_free(ram_addr_t addr)
xen_invalidate_map_cache_entry(block->host);
#ifndef _WIN32
} else if (block->fd >= 0) {
munmap(block->host, block->length);
munmap(block->host, block->max_length);
close(block->fd);
#endif
} else {
qemu_anon_ram_free(block->host, block->length);
qemu_anon_ram_free(block->host, block->max_length);
}
g_free(block);
break;
Expand All @@ -1499,7 +1503,7 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length)

QTAILQ_FOREACH(block, &ram_list.blocks, next) {
offset = addr - block->offset;
if (offset < block->length) {
if (offset < block->max_length) {
vaddr = ramblock_ptr(block, offset);
if (block->flags & RAM_PREALLOC) {
;
Expand Down Expand Up @@ -1575,7 +1579,7 @@ void *qemu_get_ram_ptr(ram_addr_t addr)
return xen_map_cache(addr, 0, 0);
} else if (block->host == NULL) {
block->host =
xen_map_cache(block->offset, block->length, 1);
xen_map_cache(block->offset, block->max_length, 1);
}
}
return ramblock_ptr(block, addr - block->offset);
Expand All @@ -1594,9 +1598,9 @@ static void *qemu_ram_ptr_length(ram_addr_t addr, hwaddr *size)
RAMBlock *block;

QTAILQ_FOREACH(block, &ram_list.blocks, next) {
if (addr - block->offset < block->length) {
if (addr - block->offset + *size > block->length)
*size = block->length - addr + block->offset;
if (addr - block->offset < block->max_length) {
if (addr - block->offset + *size > block->max_length)
*size = block->max_length - addr + block->offset;
return ramblock_ptr(block, addr - block->offset);
}
}
Expand All @@ -1619,7 +1623,7 @@ MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
}

block = ram_list.mru_block;
if (block && block->host && host - block->host < block->length) {
if (block && block->host && host - block->host < block->max_length) {
goto found;
}

Expand All @@ -1628,7 +1632,7 @@ MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
if (block->host == NULL) {
continue;
}
if (host - block->host < block->length) {
if (host - block->host < block->max_length) {
goto found;
}
}
Expand Down Expand Up @@ -2873,7 +2877,7 @@ void qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque)
RAMBlock *block;

QTAILQ_FOREACH(block, &ram_list.blocks, next) {
func(block->host, block->offset, block->length, opaque);
func(block->host, block->offset, block->used_length, opaque);
}
}
#endif
3 changes: 2 additions & 1 deletion include/exec/cpu-all.h
View file
Expand Up @@ -303,7 +303,8 @@ typedef struct RAMBlock {
struct MemoryRegion *mr;
uint8_t *host;
ram_addr_t offset;
ram_addr_t length;
ram_addr_t used_length;
ram_addr_t max_length;
uint32_t flags;
char idstr[256];
/* Reads can take either the iothread or the ramlist lock.
Expand Down

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