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hostmem: add property to map memory with MAP_SHARED

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A new "share" property can be used with the "memory-file" backend to
map memory with MAP_SHARED instead of MAP_PRIVATE.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Paolo Bonzini 2014-06-10 19:15:24 +08:00 • committed by Michael S. Tsirkin
parent a35ba7be4b
commit dbcb898118
6 changed files with 42 additions and 12 deletions
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18
exec.c
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@ -73,6 +73,9 @@ static MemoryRegion io_mem_unassigned;
/* RAM is pre-allocated and passed into qemu_ram_alloc_from_ptr */
#define RAM_PREALLOC (1 << 0)
/* RAM is mmap-ed with MAP_SHARED */
#define RAM_SHARED (1 << 1)
#endif
struct CPUTailQ cpus = QTAILQ_HEAD_INITIALIZER(cpus);
@ -1074,7 +1077,9 @@ static void *file_ram_alloc(RAMBlock *block,
perror("ftruncate");
}
area = mmap(0, memory, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
area = mmap(0, memory, PROT_READ | PROT_WRITE,
(block->flags & RAM_SHARED ? MAP_SHARED : MAP_PRIVATE),
fd, 0);
if (area == MAP_FAILED) {
error_setg_errno(errp, errno,
"unable to map backing store for hugepages");
@ -1286,7 +1291,7 @@ static ram_addr_t ram_block_add(RAMBlock *new_block)
#ifdef __linux__
ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
const char *mem_path,
bool share, const char *mem_path,
Error **errp)
{
RAMBlock *new_block;
@ -1311,6 +1316,7 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
new_block = g_malloc0(sizeof(*new_block));
new_block->mr = mr;
new_block->length = size;
new_block->flags = share ? RAM_SHARED : 0;
new_block->host = file_ram_alloc(new_block, size,
mem_path, errp);
if (!new_block->host) {
@ -1413,12 +1419,8 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length)
flags = MAP_FIXED;
munmap(vaddr, length);
if (block->fd >= 0) {
#ifdef MAP_POPULATE
flags |= mem_prealloc ? MAP_POPULATE | MAP_SHARED :
MAP_PRIVATE;
#else
flags |= MAP_PRIVATE;
#endif
flags |= (block->flags & RAM_SHARED ?
MAP_SHARED : MAP_PRIVATE);
area = mmap(vaddr, length, PROT_READ | PROT_WRITE,
flags, block->fd, offset);
} else {