Allow RAM MemoryRegion to be created from an offset in a file, instead of allocating at offset of 0 by default. This is needed to synchronize RAM between QEMU & remote process.
Signed-off-by: Jagannathan Raman <jag.ra...@oracle.com> Signed-off-by: John G Johnson <john.g.john...@oracle.com> Signed-off-by: Elena Ufimtseva <elena.ufimts...@oracle.com> Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com> --- backends/hostmem-memfd.c | 2 +- exec.c | 11 +++++++---- hw/misc/ivshmem.c | 3 ++- include/exec/memory.h | 2 ++ include/exec/ram_addr.h | 2 +- include/qemu/mmap-alloc.h | 3 ++- softmmu/memory.c | 3 ++- util/mmap-alloc.c | 7 ++++--- util/oslib-posix.c | 2 +- 9 files changed, 22 insertions(+), 13 deletions(-) diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c index 4c040a7..19c4f63 100644 --- a/backends/hostmem-memfd.c +++ b/backends/hostmem-memfd.c @@ -56,7 +56,7 @@ memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) name = host_memory_backend_get_name(backend); memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name, backend->size, - backend->share, fd, errp); + backend->share, fd, 0, errp); g_free(name); } diff --git a/exec.c b/exec.c index 6f381f9..564a6b7 100644 --- a/exec.c +++ b/exec.c @@ -1832,6 +1832,7 @@ static void *file_ram_alloc(RAMBlock *block, ram_addr_t memory, int fd, bool truncate, + off_t offset, Error **errp) { void *area; @@ -1882,7 +1883,8 @@ static void *file_ram_alloc(RAMBlock *block, } area = qemu_ram_mmap(fd, memory, block->mr->align, - block->flags & RAM_SHARED, block->flags & RAM_PMEM); + block->flags & RAM_SHARED, block->flags & RAM_PMEM, + offset); if (area == MAP_FAILED) { error_setg_errno(errp, errno, "unable to map backing store for guest RAM"); @@ -2314,7 +2316,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp, bool shared) #ifdef CONFIG_POSIX RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, uint32_t ram_flags, int fd, - Error **errp) + off_t offset, Error **errp) { RAMBlock *new_block; Error *local_err = NULL; @@ -2367,7 +2369,8 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, new_block->used_length = size; new_block->max_length = size; new_block->flags = ram_flags; - new_block->host = file_ram_alloc(new_block, size, fd, !file_size, errp); + new_block->host = file_ram_alloc(new_block, size, fd, !file_size, offset, + errp); if (!new_block->host) { g_free(new_block); return NULL; @@ -2397,7 +2400,7 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr, return NULL; } - block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, errp); + block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, 0, errp); if (!block) { if (created) { unlink(mem_path); diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c index 2b6882f..5ffaa72 100644 --- a/hw/misc/ivshmem.c +++ b/hw/misc/ivshmem.c @@ -492,7 +492,8 @@ static void process_msg_shmem(IVShmemState *s, int fd, Error **errp) /* mmap the region and map into the BAR2 */ memory_region_init_ram_from_fd(&s->server_bar2, OBJECT(s), - "ivshmem.bar2", size, true, fd, &local_err); + "ivshmem.bar2", size, true, fd, 0, + &local_err); if (local_err) { error_propagate(errp, local_err); return; diff --git a/include/exec/memory.h b/include/exec/memory.h index 307e527..608a73f 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -908,6 +908,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, * @size: size of the region. * @share: %true if memory must be mmaped with the MAP_SHARED flag * @fd: the fd to mmap. + * @offset: offset within the file referenced by fd * @errp: pointer to Error*, to store an error if it happens. * * Note that this function does not do anything to cause the data in the @@ -919,6 +920,7 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr, uint64_t size, bool share, int fd, + ram_addr_t offset, Error **errp); #endif diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h index 3ef729a..34b2bce 100644 --- a/include/exec/ram_addr.h +++ b/include/exec/ram_addr.h @@ -121,7 +121,7 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr, Error **errp); RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, uint32_t ram_flags, int fd, - Error **errp); + off_t offset, Error **errp); RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host, MemoryRegion *mr, Error **errp); diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h index e786266..4f57985 100644 --- a/include/qemu/mmap-alloc.h +++ b/include/qemu/mmap-alloc.h @@ -25,7 +25,8 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared, - bool is_pmem); + bool is_pmem, + off_t start); void qemu_ram_munmap(int fd, void *ptr, size_t size); diff --git a/softmmu/memory.c b/softmmu/memory.c index af25987..993c5b3 100644 --- a/softmmu/memory.c +++ b/softmmu/memory.c @@ -1576,6 +1576,7 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr, uint64_t size, bool share, int fd, + ram_addr_t offset, Error **errp) { Error *err = NULL; @@ -1585,7 +1586,7 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr, mr->destructor = memory_region_destructor_ram; mr->ram_block = qemu_ram_alloc_from_fd(size, mr, share ? RAM_SHARED : 0, - fd, &err); + fd, offset, &err); mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0; if (err) { mr->size = int128_zero(); diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 27dcccd..a28f702 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -86,7 +86,8 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared, - bool is_pmem) + bool is_pmem, + off_t start) { int flags; int map_sync_flags = 0; @@ -147,7 +148,7 @@ void *qemu_ram_mmap(int fd, offset = QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)guardptr; ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, - flags | map_sync_flags, fd, 0); + flags | map_sync_flags, fd, start); if (ptr == MAP_FAILED && map_sync_flags) { if (errno == ENOTSUP) { @@ -172,7 +173,7 @@ void *qemu_ram_mmap(int fd, * we will remove these flags to handle compatibility. */ ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, - flags, fd, 0); + flags, fd, start); } if (ptr == MAP_FAILED) { diff --git a/util/oslib-posix.c b/util/oslib-posix.c index ad8001a..72ad0b9 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -227,7 +227,7 @@ void *qemu_memalign(size_t alignment, size_t size) void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared) { size_t align = QEMU_VMALLOC_ALIGN; - void *ptr = qemu_ram_mmap(-1, size, align, shared, false); + void *ptr = qemu_ram_mmap(-1, size, align, shared, false, 0); if (ptr == MAP_FAILED) { return NULL; -- 1.8.3.1