On 11/6/19 12:40 AM, Beata Michalska wrote:
> +void qemu_ram_writeback(RAMBlock *block, ram_addr_t start, ram_addr_t length)
> +{
> + void *addr = ramblock_ptr(block, start);
> +
> + /*
> + * The requested range might spread up to the very end of the block
> + */
> + if ((start + length) > block->used_length) {
> + qemu_log("%s: sync range outside the block boundaries: "
> + "start: " RAM_ADDR_FMT " length: " RAM_ADDR_FMT
> + " block length: " RAM_ADDR_FMT " Narrowing down ..." ,
> + __func__, start, length, block->used_length);
> + length = block->used_length - start;
> + }
qemu_log_mask w/ GUEST_ERROR? How do we expect the length to overflow?
> +#ifdef CONFIG_LIBPMEM
> + /* The lack of support for pmem should not block the sync */
> + if (ramblock_is_pmem(block)) {
> + pmem_persist(addr, length);
> + } else
> +#endif
Perhaps better to return out of that if block than have the dangling else.
> +/**
> + * Sync changes made to the memory mapped file back to the backing
> + * storage. For POSIX compliant systems this will simply fallback
> + * to regular msync call (thus the required alignment). Otherwise
> + * it will trigger whole file sync (including the metadata case
> + * there is no support to skip that otherwise)
> + *
> + * @addr - start of the memory area to be synced
> + * @length - length of the are to be synced
> + * @align - alignment (expected to be PAGE_SIZE)
> + * @fd - file descriptor for the file to be synced
> + * (mandatory only for POSIX non-compliant systems)
> + */
> +int qemu_msync(void *addr, size_t length, size_t align, int fd)
> +{
> +#ifdef CONFIG_POSIX
> + size_t align_mask;
> +
> + /* Bare minimum of sanity checks on the alignment */
> + /* The start address needs to be a multiple of PAGE_SIZE */
> + align = MAX(align, qemu_real_host_page_size);
> + align_mask = ~(qemu_real_host_page_size - 1);
> + align = (align + ~align_mask) & align_mask;
> +
> + align_mask = ~(align - 1);
I don't understand what you're trying to do with align.
You pass in qemu_host_page_size from the one caller, and then adjust it for
qemu_real_host_page_size?
Why pass in anything at all, and just use qemu_real_host_page_mask?
> + /**
> + * There are no strict reqs as per the length of mapping
> + * to be synced. Still the length needs to follow the address
> + * alignment changes. Additionally - round the size to the multiple
> + * of requested alignment (expected as PAGE_SIZE)
> + */
> + length += ((uintptr_t)addr & (align - 1));
> + length = (length + ~align_mask) & align_mask;
> +
> + addr = (void *)((uintptr_t)addr & align_mask);
> +
> + return msync(addr, length, MS_SYNC);
> +#else /* CONFIG_POSIX */
> + /**
> + * Perform the sync based on the file descriptor
> + * The sync range will most probably be wider than the one
> + * requested - but it will still get the job done
> + */
> + return qemu_fdatasync(fd);
> +#endif /* CONFIG_POSIX */
> +}
r~
