[Xen-changelog] [xen-unstable] x86/vioapic: clear remote IRR when switching RTE to edge triggered mode

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxx>
# Date 1321864171 -3600
# Node ID 9c350ab8d3ea64866421de756ab2bf3daaf63187
# Parent  335e8273a3f34a5e2972643a028f83684609f1c1
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@xxxxxxxx>
Tested-by: Olaf Hering <olaf@xxxxxxxxx>
---


diff -r 335e8273a3f3 -r 9c350ab8d3ea xen/arch/x86/hvm/vioapic.c
--- a/xen/arch/x86/hvm/vioapic.c        Sat Nov 19 22:13:51 2011 +0000
+++ b/xen/arch/x86/hvm/vioapic.c        Mon Nov 21 09:29:31 2011 +0100
@@ -154,8 +154,9 @@
     {
         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] )
     {

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