On Fri, Dec 4, 2020 at 6:13 PM Marc-André Lureau wrote: > > > On Wed, Dec 2, 2020 at 12:23 AM Jagannathan Raman > wrote: > >> 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 >> Signed-off-by: John G Johnson >> Signed-off-by: Elena Ufimtseva >> Reviewed-by: Stefan Hajnoczi >> --- >> include/exec/memory.h | 2 ++ >> include/exec/ram_addr.h | 2 +- >> include/qemu/mmap-alloc.h | 3 ++- >> backends/hostmem-memfd.c | 2 +- >> hw/misc/ivshmem.c | 3 ++- >> softmmu/memory.c | 3 ++- >> softmmu/physmem.c | 11 +++++++---- >> util/mmap-alloc.c | 7 ++++--- >> util/oslib-posix.c | 2 +- >> 9 files changed, 22 insertions(+), 13 deletions(-) >> >> diff --git a/include/exec/memory.h b/include/exec/memory.h >> index 0f3e6bc..7bcaada 100644 >> --- a/include/exec/memory.h >> +++ b/include/exec/memory.h >> @@ -980,6 +980,7 @@ 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 >> @@ -991,6 +992,7 @@ 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 c6d2ef1..d465a48 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); >> > > I'd suggest to keep the variable name "offset", to avoid potential > confusion (it's also the name of the mmap() argument). > I realize the inner offset variable will need to be renamed then, I'd suggest guard_offset for instance. > >> void qemu_ram_munmap(int fd, void *ptr, size_t size); >> >> diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c >> index e5626d4..69b0ae3 100644 >> --- a/backends/hostmem-memfd.c >> +++ b/backends/hostmem-memfd.c >> @@ -55,7 +55,7 @@ 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/hw/misc/ivshmem.c b/hw/misc/ivshmem.c >> index e321e5c..8d3e1ee 100644 >> --- a/hw/misc/ivshmem.c >> +++ b/hw/misc/ivshmem.c >> @@ -494,7 +494,8 @@ 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/softmmu/memory.c b/softmmu/memory.c >> index 11ca94d..e4ed0e4 100644 >> --- a/softmmu/memory.c >> +++ b/softmmu/memory.c >> @@ -1612,6 +1612,7 @@ 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; >> @@ -1621,7 +1622,7 @@ 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/softmmu/physmem.c b/softmmu/physmem.c >> index 3027747..e0b8fc6 100644 >> --- a/softmmu/physmem.c >> +++ b/softmmu/physmem.c >> @@ -1461,6 +1461,7 @@ static void *file_ram_alloc(RAMBlock *block, >> ram_addr_t memory, >> int fd, >> bool truncate, >> + off_t offset, >> Error **errp) >> { >> void *area; >> @@ -1511,7 +1512,8 @@ 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"); >> @@ -1943,7 +1945,7 @@ 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; >> @@ -1996,7 +1998,8 @@ 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; >> @@ -2026,7 +2029,7 @@ 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/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 f15234b..93874df 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 >> >> > > -- > Marc-André Lureau > -- Marc-André Lureau