On Thu, Jul 20, 2017 at 09:52:34AM +0300, Alexey Perevalov wrote:
> This patch adds ability to track down already received
> pages, it's necessary for calculation vCPU block time in
> postcopy migration feature, maybe for restore after
> postcopy migration failure.
> Also it's necessary to solve shared memory issue in
> postcopy livemigration. Information about received pages
> will be transferred to the software virtual bridge
> (e.g. OVS-VSWITCHD), to avoid fallocate (unmap) for
> already received pages. fallocate syscall is required for
> remmaped shared memory, due to remmaping itself blocks
> ioctl(UFFDIO_COPY, ioctl in this case will end with EEXIT
> error (struct page is exists after remmap).
>
> Bitmap is placed into RAMBlock as another postcopy/precopy
> related bitmaps.
>
> Reviewed-by: Peter Xu <[email protected]>
> Signed-off-by: Alexey Perevalov <[email protected]>
> ---
[...]
> static int qemu_ufd_copy_ioctl(int userfault_fd, void *host_addr,
> - void *from_addr, uint64_t pagesize)
> + void *from_addr, uint64_t pagesize, RAMBlock
> *rb)
> {
> + int ret;
> if (from_addr) {
> struct uffdio_copy copy_struct;
> copy_struct.dst = (uint64_t)(uintptr_t)host_addr;
> copy_struct.src = (uint64_t)(uintptr_t)from_addr;
> copy_struct.len = pagesize;
> copy_struct.mode = 0;
> - return ioctl(userfault_fd, UFFDIO_COPY, ©_struct);
> + ret = ioctl(userfault_fd, UFFDIO_COPY, ©_struct);
> } else {
> struct uffdio_zeropage zero_struct;
> zero_struct.range.start = (uint64_t)(uintptr_t)host_addr;
> zero_struct.range.len = pagesize;
> zero_struct.mode = 0;
> - return ioctl(userfault_fd, UFFDIO_ZEROPAGE, &zero_struct);
> + ret = ioctl(userfault_fd, UFFDIO_ZEROPAGE, &zero_struct);
> + }
> + if (!ret) {
> + ramblock_recv_bitmap_set(host_addr, rb);
Wait...
Now we are using 4k-page/bit bitmap, do we need to take care of the
huge pages here? Looks like we are only setting the first bit of it
if it is a huge page?
--
Peter Xu
