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>

diff --git a/xen/arch/x86/hvm/vioapic.c b/xen/arch/x86/hvm/vioapic.c
index 1d5cbc85142938d4ca7e26ec74a4f611321982ed..403224f82899da1cc44bf4c6672631d6b4385aff 100644 (file)
--- a/xen/arch/x86/hvm/vioapic.c
+++ b/xen/arch/x86/hvm/vioapic.c
@@ -154,8 +154,9 @@ 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] )
     {