From: Steve Sistare <steven.sist...@oracle.com> 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.sist...@oracle.com> Reviewed-by: Peter Xu <pet...@redhat.com> Link: https://lore.kernel.org/r/1736967650-129648-6-git-send-email-steven.sist...@oracle.com Signed-off-by: Fabiano Rosas <faro...@suse.de> --- backends/hostmem-epc.c | 2 +- backends/hostmem-file.c | 2 +- backends/hostmem-memfd.c | 2 +- backends/hostmem-ram.c | 2 +- include/exec/memory.h | 10 ++++++++++ system/physmem.c | 15 ++++++++++++--- 6 files changed, 26 insertions(+), 7 deletions(-) diff --git a/backends/hostmem-epc.c b/backends/hostmem-epc.c index eb4b95dfd7..1fa2d031e4 100644 --- a/backends/hostmem-epc.c +++ b/backends/hostmem-epc.c @@ -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); } diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index 46321fda84..691a827819 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -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; diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c index d4d0620e6c..1672da9e30 100644 --- a/backends/hostmem-memfd.c +++ b/backends/hostmem-memfd.c @@ -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, diff --git a/backends/hostmem-ram.c b/backends/hostmem-ram.c index 39aac6bf35..868ae6ca80 100644 --- a/backends/hostmem-ram.c +++ b/backends/hostmem-ram.c @@ -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), diff --git a/include/exec/memory.h b/include/exec/memory.h index 3ee1901b52..9f73b59867 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -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, diff --git a/system/physmem.c b/system/physmem.c index e4355649e9..03fac0a64f 100644 --- a/system/physmem.c +++ b/system/physmem.c @@ -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); } -- 2.35.3
