diff options
| -rw-r--r-- | exec.c | 22 | ||||
| -rw-r--r-- | include/exec/memory.h | 9 | ||||
| -rw-r--r-- | memory.c | 14 |
3 files changed, 22 insertions, 23 deletions
@@ -1786,19 +1786,11 @@ void *qemu_get_ram_block_host_ptr(ram_addr_t addr) * or address_space_rw instead. For local memory (e.g. video ram) that the * device owns, use memory_region_get_ram_ptr. * - * By the time this function returns, the returned pointer is not protected - * by RCU anymore. If the caller is not within an RCU critical section and - * does not hold the iothread lock, it must have other means of protecting the - * pointer, such as a reference to the region that includes the incoming - * ram_addr_t. + * Called within RCU critical section. */ void *qemu_get_ram_ptr(ram_addr_t addr) { - RAMBlock *block; - void *ptr; - - rcu_read_lock(); - block = qemu_get_ram_block(addr); + RAMBlock *block = qemu_get_ram_block(addr); if (xen_enabled() && block->host == NULL) { /* We need to check if the requested address is in the RAM @@ -1806,17 +1798,12 @@ void *qemu_get_ram_ptr(ram_addr_t addr) * In that case just map until the end of the page. */ if (block->offset == 0) { - ptr = xen_map_cache(addr, 0, 0); - goto unlock; + return xen_map_cache(addr, 0, 0); } block->host = xen_map_cache(block->offset, block->max_length, 1); } - ptr = ramblock_ptr(block, addr - block->offset); - -unlock: - rcu_read_unlock(); - return ptr; + return ramblock_ptr(block, addr - block->offset); } /* Return a host pointer to guest's ram. Similar to qemu_get_ram_ptr @@ -1954,6 +1941,7 @@ MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr) return block->mr; } +/* Called within RCU critical section. */ static void notdirty_mem_write(void *opaque, hwaddr ram_addr, uint64_t val, unsigned size) { diff --git a/include/exec/memory.h b/include/exec/memory.h index 0f07159bb4..9bbd247c38 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -656,8 +656,13 @@ int memory_region_get_fd(MemoryRegion *mr); * memory_region_get_ram_ptr: Get a pointer into a RAM memory region. * * Returns a host pointer to a RAM memory region (created with - * memory_region_init_ram() or memory_region_init_ram_ptr()). Use with - * care. + * memory_region_init_ram() or memory_region_init_ram_ptr()). + * + * Use with care; by the time this function returns, the returned pointer is + * not protected by RCU anymore. If the caller is not within an RCU critical + * section and does not hold the iothread lock, it must have other means of + * protecting the pointer, such as a reference to the region that includes + * the incoming ram_addr_t. * * @mr: the memory region being queried. */ @@ -1577,13 +1577,19 @@ int memory_region_get_fd(MemoryRegion *mr) void *memory_region_get_ram_ptr(MemoryRegion *mr) { - if (mr->alias) { - return memory_region_get_ram_ptr(mr->alias) + mr->alias_offset; - } + void *ptr; + uint64_t offset = 0; + rcu_read_lock(); + while (mr->alias) { + offset += mr->alias_offset; + mr = mr->alias; + } assert(mr->ram_addr != RAM_ADDR_INVALID); + ptr = qemu_get_ram_ptr(mr->ram_addr & TARGET_PAGE_MASK); + rcu_read_unlock(); - return qemu_get_ram_ptr(mr->ram_addr & TARGET_PAGE_MASK); + return ptr + offset; } void memory_region_ram_resize(MemoryRegion *mr, ram_addr_t newsize, Error **errp) |