On Fri, 25 Nov 2016, Jan Beulich wrote:
> We should not consume the second slot if it didn't get written yet.
> Normal writers - i.e. Xen - would not update write_pointer between the
> two writes, but the page may get fiddled with by the guest itself, and
> we're better off avoiding to enter an infinite loop in that case.
>
> Reported-by: yanghongke <yanghon...@huawei.com>
> Signed-off-by: Jan Beulich <jbeul...@suse.com>
Reviewed-by: Stefano Stabellini <sstabell...@kernel.org>
> v2: Bail (using hw_error()) instead of just breaking the loop.
>
> --- a/xen-hvm.c
> +++ b/xen-hvm.c
> @@ -1021,6 +1021,9 @@ static int handle_buffered_iopage(XenIOS
> xen_rmb();
> qw = (req.size == 8);
> if (qw) {
> + if (rdptr + 1 == wrptr) {
> + hw_error("Incomplete quad word buffered ioreq");
> + }
> buf_req = &buf_page->buf_ioreq[(rdptr + 1) %
> IOREQ_BUFFER_SLOT_NUM];
> req.data |= ((uint64_t)buf_req->data) << 32;
>
>
>
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