migration/ram: Factor out populating pages readable in ram_block_populate_pages()
Let's factor out prefaulting/populating to make further changes easier to review and add a comment what we are actually expecting to happen. While at it, use the actual page size of the ramblock, which defaults to qemu_real_host_page_size for anonymous memory. Further, rename ram_block_populate_pages() to ram_block_populate_read() as well, to make it clearer what we are doing. In the future, we might want to use MADV_POPULATE_READ to speed up population. Reviewed-by: Peter Xu <peterx@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
parent
7648297d40
commit
f7b9dcfbcf
|
@ -1639,26 +1639,35 @@ out:
|
|||
return ret;
|
||||
}
|
||||
|
||||
static inline void populate_read_range(RAMBlock *block, ram_addr_t offset,
|
||||
ram_addr_t size)
|
||||
{
|
||||
/*
|
||||
* We read one byte of each page; this will preallocate page tables if
|
||||
* required and populate the shared zeropage on MAP_PRIVATE anonymous memory
|
||||
* where no page was populated yet. This might require adaption when
|
||||
* supporting other mappings, like shmem.
|
||||
*/
|
||||
for (; offset < size; offset += block->page_size) {
|
||||
char tmp = *((char *)block->host + offset);
|
||||
|
||||
/* Don't optimize the read out */
|
||||
asm volatile("" : "+r" (tmp));
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* ram_block_populate_pages: populate memory in the RAM block by reading
|
||||
* an integer from the beginning of each page.
|
||||
* ram_block_populate_read: preallocate page tables and populate pages in the
|
||||
* RAM block by reading a byte of each page.
|
||||
*
|
||||
* Since it's solely used for userfault_fd WP feature, here we just
|
||||
* hardcode page size to qemu_real_host_page_size.
|
||||
*
|
||||
* @block: RAM block to populate
|
||||
*/
|
||||
static void ram_block_populate_pages(RAMBlock *block)
|
||||
static void ram_block_populate_read(RAMBlock *block)
|
||||
{
|
||||
char *ptr = (char *) block->host;
|
||||
|
||||
for (ram_addr_t offset = 0; offset < block->used_length;
|
||||
offset += qemu_real_host_page_size) {
|
||||
char tmp = *(ptr + offset);
|
||||
|
||||
/* Don't optimize the read out */
|
||||
asm volatile("" : "+r" (tmp));
|
||||
}
|
||||
populate_read_range(block, 0, block->used_length);
|
||||
}
|
||||
|
||||
/*
|
||||
|
@ -1684,7 +1693,7 @@ void ram_write_tracking_prepare(void)
|
|||
* UFFDIO_WRITEPROTECT_MODE_WP mode setting would silently skip
|
||||
* pages with pte_none() entries in page table.
|
||||
*/
|
||||
ram_block_populate_pages(block);
|
||||
ram_block_populate_read(block);
|
||||
}
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in New Issue