Commit dbcb8981 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Michael S. Tsirkin
Browse files

hostmem: add property to map memory with MAP_SHARED 



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: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarHu Tao <hutao@cn.fujitsu.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent a35ba7be

backends/hostmem-file.c

+25 −1
Original line number Diff line number Diff line
@@ -28,6 +28,8 @@ typedef struct HostMemoryBackendFile HostMemoryBackendFile; 


struct HostMemoryBackendFile {

    HostMemoryBackend parent_obj;



    bool share;

    char *mem_path;

};
@@ -51,7 +53,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) 
        backend->force_prealloc = mem_prealloc;

        memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),

                                 object_get_canonical_path(OBJECT(backend)),

                                 backend->size,

                                 backend->size, fb->share,

                                 fb->mem_path, errp);

    }

#endif
@@ -87,9 +89,31 @@ static void set_mem_path(Object *o, const char *str, Error **errp) 
    fb->mem_path = g_strdup(str);

}



static bool file_memory_backend_get_share(Object *o, Error **errp)

{

    HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);



    return fb->share;

}



static void file_memory_backend_set_share(Object *o, bool value, Error **errp)

{

    HostMemoryBackend *backend = MEMORY_BACKEND(o);

    HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);



    if (memory_region_size(&backend->mr)) {

        error_setg(errp, "cannot change property value");

        return;

    }

    fb->share = value;

}



static void

file_backend_instance_init(Object *o)

{

    object_property_add_bool(o, "share",

                        file_memory_backend_get_share,

                        file_memory_backend_set_share, NULL);

    object_property_add_str(o, "mem-path", get_mem_path,

                            set_mem_path, NULL);

}

exec.c

+10 −8
Original line number Diff line number Diff line
@@ -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 {

include/exec/memory.h

+2 −0
Original line number Diff line number Diff line
@@ -321,6 +321,7 @@ void memory_region_init_ram(MemoryRegion *mr, 
 * @owner: the object that tracks the region's reference count

 * @name: the name of the region.

 * @size: size of the region.

 * @share: %true if memory must be mmaped with the MAP_SHARED flag

 * @path: the path in which to allocate the RAM.

 * @errp: pointer to Error*, to store an error if it happens.

 */
@@ -328,6 +329,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, 
                                      struct Object *owner,

                                      const char *name,

                                      uint64_t size,

                                      bool share,

                                      const char *path,

                                      Error **errp);

#endif

include/exec/ram_addr.h

+2 −1
Original line number Diff line number Diff line
@@ -23,7 +23,8 @@ 
#include "hw/xen/xen.h"



ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,

                                    const char *mem_path, Error **errp);

                                    bool share, const char *mem_path,

                                    Error **errp);

ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,

                                   MemoryRegion *mr);

ram_addr_t qemu_ram_alloc(ram_addr_t size, MemoryRegion *mr);

memory.c

+2 −1
Original line number Diff line number Diff line
@@ -1038,6 +1038,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, 
                                      struct Object *owner,

                                      const char *name,

                                      uint64_t size,

                                      bool share,

                                      const char *path,

                                      Error **errp)

{
@@ -1045,7 +1046,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, 
    mr->ram = true;

    mr->terminates = true;

    mr->destructor = memory_region_destructor_ram;

    mr->ram_addr = qemu_ram_alloc_from_file(size, mr, path, errp);

    mr->ram_addr = qemu_ram_alloc_from_file(size, mr, share, path, errp);

}

#endif