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| author | Alexander Graf <graf@amazon.com> | 2023-04-03 22:14:21 +0000 |
|---|---|---|
| committer | David Hildenbrand <david@redhat.com> | 2023-05-23 16:47:03 +0200 |
| commit | 4b870dc4d0c0895859d34d14ce0272a4bcbccf78 (patch) | |
| tree | 8af35d1db6ba0cd63419627870a0a75aec9bf150 /softmmu | |
| parent | 886c0453cbf10eebd42a9ccf89c3e46eb389c357 (diff) | |
| download | qemu-4b870dc4d0c0895859d34d14ce0272a4bcbccf78.zip qemu-4b870dc4d0c0895859d34d14ce0272a4bcbccf78.tar.gz qemu-4b870dc4d0c0895859d34d14ce0272a4bcbccf78.tar.bz2 | |
hostmem-file: add offset option
Add an option for hostmem-file to start the memory object at an offset
into the target file. This is useful if multiple memory objects reside
inside the same target file, such as a device node.
In particular, it's useful to map guest memory directly into /dev/mem
for experimentation.
To make this work consistently, also fix up all places in QEMU that
expect fd offsets to be 0.
Signed-off-by: Alexander Graf <graf@amazon.com>
Message-Id: <20230403221421.60877-1-graf@amazon.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Diffstat (limited to 'softmmu')
| -rw-r--r-- | softmmu/memory.c | 3 | ||||
| -rw-r--r-- | softmmu/physmem.c | 17 |
2 files changed, 14 insertions, 6 deletions
diff --git a/softmmu/memory.c b/softmmu/memory.c index 9ee4131..7d9494c 100644 --- a/softmmu/memory.c +++ b/softmmu/memory.c @@ -1619,6 +1619,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, uint64_t align, uint32_t ram_flags, const char *path, + ram_addr_t offset, bool readonly, Error **errp) { @@ -1630,7 +1631,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, mr->destructor = memory_region_destructor_ram; mr->align = align; mr->ram_block = qemu_ram_alloc_from_file(size, mr, ram_flags, path, - readonly, &err); + offset, readonly, &err); if (err) { mr->size = int128_zero(); object_unparent(OBJECT(mr)); diff --git a/softmmu/physmem.c b/softmmu/physmem.c index efaed36..9d7e172 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -1369,6 +1369,11 @@ static void *file_ram_alloc(RAMBlock *block, error_setg(errp, "alignment 0x%" PRIx64 " must be a power of two", block->mr->align); return NULL; + } else if (offset % block->page_size) { + error_setg(errp, "offset 0x%" PRIx64 + " must be multiples of page size 0x%zx", + offset, block->page_size); + return NULL; } block->mr->align = MAX(block->page_size, block->mr->align); #if defined(__s390x__) @@ -1400,7 +1405,7 @@ static void *file_ram_alloc(RAMBlock *block, * those labels. Therefore, extending the non-empty backend file * is disabled as well. */ - if (truncate && ftruncate(fd, memory)) { + if (truncate && ftruncate(fd, offset + memory)) { perror("ftruncate"); } @@ -1416,6 +1421,7 @@ static void *file_ram_alloc(RAMBlock *block, } block->fd = fd; + block->fd_offset = offset; return area; } #endif @@ -1889,7 +1895,7 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, size = HOST_PAGE_ALIGN(size); file_size = get_file_size(fd); - if (file_size > 0 && file_size < size) { + if (file_size > offset && file_size < (offset + size)) { error_setg(errp, "backing store size 0x%" PRIx64 " does not match 'size' option 0x" RAM_ADDR_FMT, file_size, size); @@ -1929,7 +1935,7 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr, uint32_t ram_flags, const char *mem_path, - bool readonly, Error **errp) + off_t offset, bool readonly, Error **errp) { int fd; bool created; @@ -1941,7 +1947,8 @@ 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, 0, readonly, errp); + block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, offset, readonly, + errp); if (!block) { if (created) { unlink(mem_path); @@ -2075,7 +2082,7 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length) flags |= block->flags & RAM_NORESERVE ? MAP_NORESERVE : 0; if (block->fd >= 0) { area = mmap(vaddr, length, PROT_READ | PROT_WRITE, - flags, block->fd, offset); + flags, block->fd, offset + block->fd_offset); } else { flags |= MAP_ANONYMOUS; area = mmap(vaddr, length, PROT_READ | PROT_WRITE, |