x86/vioapic: clear remote IRR when switching RTE to edge triggered

mode

Xen itself (as much as Linux) relies on this behavior, so it should
also emulate it properly. Not doing so reportedly gets in the way of
kexec inside a HVM guest.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Olaf Hering <olaf@aepfle.de>
xen-unstable changeset:   24168:9c350ab8d3ea
xen-unstable date:        Mon Nov 21 09:29:31 2011 +0100
Committed-by: Keir Fraser <keir@xen.org>

diff --git a/xen/arch/x86/hvm/vioapic.c b/xen/arch/x86/hvm/vioapic.c
index 9c0033a23e3ca347c27c6c391d6a0ae6300a12e6..1d6c3dffc68b4ec24783b7c272f89fc6c6236440 100644 (file)
--- a/xen/arch/x86/hvm/vioapic.c
+++ b/xen/arch/x86/hvm/vioapic.c
@@ -153,8 +153,9 @@ static void vioapic_write_redirent(
     {
         vlapic_adjust_i8259_target(d);
     }
-    else if ( (ent.fields.trig_mode == VIOAPIC_LEVEL_TRIG) &&
-              !ent.fields.mask &&
+    else if ( ent.fields.trig_mode == VIOAPIC_EDGE_TRIG )
+        pent->fields.remote_irr = 0;
+    else if ( !ent.fields.mask &&
               !ent.fields.remote_irr &&
               hvm_irq->gsi_assert_count[idx] )
     {