xen-hvm: Allow disabling buffer_io_timer

commit f37f29d31488 "xen: slightly simplify bufioreq handling" hard
coded setting req.count = 1 during initial field setup before the main
loop.  This missed a subtlety that an early exit from the loop when
there are no ioreqs to process, would have req.count == 0 for the return
value.  handle_buffered_io() would then remove state->buffered_io_timer.
Instead handle_buffered_iopage() is basically always returning true and
handle_buffered_io() always re-setting the timer.

Restore the disabling of the timer by introducing a new handled_ioreq
boolean and use as the return value.  The named variable will more
clearly show the intent of the code.

Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Message-Id: <20211210193434.75566-1-jandryuk@gmail.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
(cherry picked from commit 9288e803e61e8d56d1c6c6aa8beb58596fb84ed9)

diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c
index 9b432773f026bf820e15691b2d1915b2a6891811..91efb1f7cfd4f05ac3a1b336f7e75ddab9591d2d 100644 (file)
--- a/hw/i386/xen/xen-hvm.c
+++ b/hw/i386/xen/xen-hvm.c
@@ -1085,10 +1085,11 @@ static void handle_ioreq(XenIOState *state, ioreq_t *req)
     }
 }
 
-static int handle_buffered_iopage(XenIOState *state)
+static bool handle_buffered_iopage(XenIOState *state)
 {
     buffered_iopage_t *buf_page = state->buffered_io_page;
     buf_ioreq_t *buf_req = NULL;
+    bool handled_ioreq = false;
     ioreq_t req;
     int qw;
 
@@ -1142,9 +1143,10 @@ static int handle_buffered_iopage(XenIOState *state)
         assert(!req.data_is_ptr);
 
         qatomic_add(&buf_page->read_pointer, qw + 1);
+        handled_ioreq = true;
     }
 
-    return req.count;
+    return handled_ioreq;
 }
 
 static void handle_buffered_io(void *opaque)