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memory: add RAM_PRIVATE

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Define the RAM_PRIVATE flag.

In RAMBlock creation functions, if MAP_SHARED is 0 in the flags parameter,
in a subsequent patch the implementation may still create a shared mapping
if other conditions require it.  Callers who specifically want a private
mapping, eg for objects specified by the user, must pass RAM_PRIVATE.

After RAMBlock creation, MAP_SHARED in the block's flags indicates whether
the block is shared or private, and MAP_PRIVATE is omitted.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-6-git-send-email-steven.sistare@oracle.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
This commit is contained in:
Steve Sistare 2025-01-15 11:00:31 -08:00 committed by Fabiano Rosas
parent 9fb40bb962
commit 6169f11936
6 changed files with 26 additions and 7 deletions
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2
backends/hostmem-epc.c
View File

@ -36,7 +36,7 @@ sgx_epc_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
backend->aligned = true;
name = object_get_canonical_path(OBJECT(backend));
ram_flags = (backend->share ? RAM_SHARED : 0) | RAM_PROTECTED;
ram_flags = (backend->share ? RAM_SHARED : RAM_PRIVATE) | RAM_PROTECTED;
return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
backend->size, ram_flags, fd, 0, errp);
}

2
backends/hostmem-file.c
View File

@ -82,7 +82,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
backend->aligned = true;
name = host_memory_backend_get_name(backend);
ram_flags = backend->share ? RAM_SHARED : 0;
ram_flags = backend->share ? RAM_SHARED : RAM_PRIVATE;
ram_flags |= fb->readonly ? RAM_READONLY_FD : 0;
ram_flags |= fb->rom == ON_OFF_AUTO_ON ? RAM_READONLY : 0;
ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;

2
backends/hostmem-memfd.c
View File

@ -52,7 +52,7 @@ memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
backend->aligned = true;
name = host_memory_backend_get_name(backend);
ram_flags = backend->share ? RAM_SHARED : 0;
ram_flags = backend->share ? RAM_SHARED : RAM_PRIVATE;
ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,

2
backends/hostmem-ram.c
View File

@ -28,7 +28,7 @@ ram_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
}
name = host_memory_backend_get_name(backend);
ram_flags = backend->share ? RAM_SHARED : 0;
ram_flags = backend->share ? RAM_SHARED : RAM_PRIVATE;
ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
return memory_region_init_ram_flags_nomigrate(&backend->mr, OBJECT(backend),

10
include/exec/memory.h
View File

@ -246,6 +246,16 @@ typedef struct IOMMUTLBEvent {
/* RAM can be private that has kvm guest memfd backend */
#define RAM_GUEST_MEMFD (1 << 12)
/*
* In RAMBlock creation functions, if MAP_SHARED is 0 in the flags parameter,
* the implementation may still create a shared mapping if other conditions
* require it. Callers who specifically want a private mapping, eg objects
* specified by the user, must pass RAM_PRIVATE.
* After RAMBlock creation, MAP_SHARED in the block's flags indicates whether
* the block is shared or private, and MAP_PRIVATE is omitted.
*/
#define RAM_PRIVATE (1 << 13)
static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
IOMMUNotifierFlag flags,
hwaddr start, hwaddr end,

15
system/physmem.c
View File

@ -1952,7 +1952,11 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, ram_addr_t max_size,
ERRP_GUARD();
RAMBlock *new_block;
Error *local_err = NULL;
int64_t file_size, file_align;
int64_t file_size, file_align, share_flags;
share_flags = ram_flags & (RAM_PRIVATE | RAM_SHARED);
assert(share_flags != (RAM_SHARED | RAM_PRIVATE));
ram_flags &= ~RAM_PRIVATE;
/* Just support these ram flags by now. */
assert((ram_flags & ~(RAM_SHARED | RAM_PMEM | RAM_NORESERVE |
@ -2097,7 +2101,11 @@ RAMBlock *qemu_ram_alloc_internal(ram_addr_t size, ram_addr_t max_size,
{
RAMBlock *new_block;
Error *local_err = NULL;
int align;
int align, share_flags;
share_flags = ram_flags & (RAM_PRIVATE | RAM_SHARED);
assert(share_flags != (RAM_SHARED | RAM_PRIVATE));
ram_flags &= ~RAM_PRIVATE;
assert((ram_flags & ~(RAM_SHARED | RAM_RESIZEABLE | RAM_PREALLOC |
RAM_NORESERVE | RAM_GUEST_MEMFD)) == 0);
@ -2172,7 +2180,8 @@ RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
RAMBlock *qemu_ram_alloc(ram_addr_t size, uint32_t ram_flags,
MemoryRegion *mr, Error **errp)
{
assert((ram_flags & ~(RAM_SHARED | RAM_NORESERVE | RAM_GUEST_MEMFD)) == 0);
assert((ram_flags & ~(RAM_SHARED | RAM_NORESERVE | RAM_GUEST_MEMFD |
RAM_PRIVATE)) == 0);
return qemu_ram_alloc_internal(size, size, NULL, NULL, ram_flags, mr, errp);
}