From: Jan Beulich <jbeul...@suse.com>
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: Paul Durrant <paul.durr...@citrix.com>
Reviewed-by: Stefano Stabellini <sstabell...@kernel.org>
Signed-off-by: Stefano Stabellini <sstabell...@kernel.org>
---
xen-hvm.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/xen-hvm.c b/xen-hvm.c
index 99b8ee8..d74e233 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -1021,6 +1021,9 @@ static int handle_buffered_iopage(XenIOState *state)
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;
--
1.9.1
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