exec/cpu-common: add qemu_ram_get_fd()

Add a function to get the file descriptor for a RAMBlock. Device
emulation code typically uses the MemoryRegion APIs but vhost-style code
may use RAMBlock directly for sharing guest memory with another process.

This new API will be used by the libblkio block driver so it can share
guest memory via .bdrv_register_buf().

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20221013185908.1297568-11-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index c493510ee9c65515ee5192b44988ad36060184d7..6feaa40ca7b094b8c05e9de10882a49589095486 100644 (file)
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -92,6 +92,7 @@ void qemu_ram_set_uf_zeroable(RAMBlock *rb);
 bool qemu_ram_is_migratable(RAMBlock *rb);
 void qemu_ram_set_migratable(RAMBlock *rb);
 void qemu_ram_unset_migratable(RAMBlock *rb);
+int qemu_ram_get_fd(RAMBlock *rb);
 
 size_t qemu_ram_pagesize(RAMBlock *block);
 size_t qemu_ram_pagesize_largest(void);

diff --git a/softmmu/physmem.c b/softmmu/physmem.c
index 56e03e07b56d567209b40c491ab6f03fa0007fb9..d9578ccfd421404015e99110ac3054872fa15c48 100644 (file)
--- a/softmmu/physmem.c
+++ b/softmmu/physmem.c
@@ -1748,6 +1748,11 @@ void qemu_ram_unset_migratable(RAMBlock *rb)
     rb->flags &= ~RAM_MIGRATABLE;
 }
 
+int qemu_ram_get_fd(RAMBlock *rb)
+{
+    return rb->fd;
+}
+
 /* Called with iothread lock held.  */
 void qemu_ram_set_idstr(RAMBlock *new_block, const char *name, DeviceState *dev)
 {