[PULL,4/4] xen: ignore direction in bufioreq handling

Commit Message

Stefano Stabellini Nov. 28, 2016, 7:42 p.m. UTC

From: Jan Beulich <[e-mail]>

There's no way to communicate back read data, so only writes can ever
be usefully specified. Ignore the field, paving the road for eventually
re-using the bit for something else in a few (many?) years time.

Signed-off-by: Jan Beulich <[e-mail]>
Reviewed-by: Paul Durrant <[e-mail]>
Acked-by: Stefano Stabellini <[e-mail]>
Signed-off-by: Stefano Stabellini <[e-mail]>
---
 xen-hvm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Patch

diff --git a/xen-hvm.c b/xen-hvm.c
index 124ae10..0892361 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -997,6 +997,7 @@  static int handle_buffered_iopage(XenIOState *state)
     memset(&req, 0x00, sizeof(req));
     req.state = STATE_IOREQ_READY;
     req.count = 1;
+    req.dir = IOREQ_WRITE;
 
     for (;;) {
         uint32_t rdptr = buf_page->read_pointer, wrptr;
@@ -1014,7 +1015,6 @@  static int handle_buffered_iopage(XenIOState *state)
         req.size = 1U << buf_req->size;
         req.addr = buf_req->addr;
         req.data = buf_req->data;
-        req.dir = buf_req->dir;
         req.type = buf_req->type;
         xen_rmb();
         qw = (req.size == 8);
@@ -1031,10 +1031,12 @@  static int handle_buffered_iopage(XenIOState *state)
         handle_ioreq(state, &req);
 
         /* Only req.data may get updated by handle_ioreq(), albeit even that
-         * should not happen as such data would never make it to the guest.
+         * should not happen as such data would never make it to the guest (we
+         * can only usefully see writes here after all).
          */
         assert(req.state == STATE_IOREQ_READY);
         assert(req.count == 1);
+        assert(req.dir == IOREQ_WRITE);
         assert(!req.data_is_ptr);
 
         atomic_add(&buf_page->read_pointer, qw + 1);