mem: add share parameter to memory-backend-ram

Currently only file backed memory backend can
be created with a "share" flag in order to allow
sharing guest RAM with other processes in the host.

Add the "share" flag also to RAM Memory Backend
in order to allow remapping parts of the guest RAM
to different host virtual addresses. This is needed
by the RDMA devices in order to remap non-contiguous
QEMU virtual addresses to a contiguous virtual address range.

Moved the "share" flag to the Host Memory base class,
modified phys_mem_alloc to include the new parameter
and a new interface memory_region_init_ram_shared_nomigrate.

There are no functional changes if the new flag is not used.

Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>

1 files changed, 13 insertions, 3 deletions

diff --git a/memory.c b/memory.c
index c7f6588..6515131 100644
--- a/memory.c
+++ b/memory.c
@@ -1539,11 +1539,21 @@ void memory_region_init_ram_nomigrate(MemoryRegion *mr,
                                       uint64_t size,
                                       Error **errp)
 {
+    memory_region_init_ram_shared_nomigrate(mr, owner, name, size, false, errp);
+}
+
+void memory_region_init_ram_shared_nomigrate(MemoryRegion *mr,
+                                             Object *owner,
+                                             const char *name,
+                                             uint64_t size,
+                                             bool share,
+                                             Error **errp)
+{
     memory_region_init(mr, owner, name, size);
     mr->ram = true;
     mr->terminates = true;
     mr->destructor = memory_region_destructor_ram;
-    mr->ram_block = qemu_ram_alloc(size, mr, errp);
+    mr->ram_block = qemu_ram_alloc(size, share, mr, errp);
     mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;
 }
 
@@ -1654,7 +1664,7 @@ void memory_region_init_rom_nomigrate(MemoryRegion *mr,
     mr->readonly = true;
     mr->terminates = true;
     mr->destructor = memory_region_destructor_ram;
-    mr->ram_block = qemu_ram_alloc(size, mr, errp);
+    mr->ram_block = qemu_ram_alloc(size, false, mr, errp);
     mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0;
 }
 
@@ -1673,7 +1683,7 @@ void memory_region_init_rom_device_nomigrate(MemoryRegion *mr,
     mr->terminates = true;
     mr->rom_device = true;
     mr->destructor = memory_region_destructor_ram;
-    mr->ram_block = qemu_ram_alloc(size, mr, errp);
+    mr->ram_block = qemu_ram_alloc(size, false,  mr, errp);
 }
 
 void memory_region_init_iommu(void *_iommu_mr,