[Xen-changelog] [xen-unstable] vt-d: Fix ioapic write order in io_apic_write_remap_rte

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1281367965 -3600
# Node ID add40eb478680b6f8de7102e87fba259f721ce1d
# Parent  fe930e1b2ce8f205fb368d0cc86876cc54d761a9
vt-d: Fix ioapic write order in io_apic_write_remap_rte

At the end of io_apic_write_remap_rte, it writes new entry (remapped
interrupt) to ioapic. But it writes low 32 bits before high 32 bits,
it unmasks interrupt before writing high 32 bits if 'mask' bit in low
32 bits is cleared. Thus it may result in issues. This patch fixes
this issue by writing high 32 bits before low 32 bits.

Signed-off-by: Jiang, Yunhong <yunhong.jiang@xxxxxxxxx>
Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
---
 xen/drivers/passthrough/vtd/intremap.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff -r fe930e1b2ce8 -r add40eb47868 xen/drivers/passthrough/vtd/intremap.c
--- a/xen/drivers/passthrough/vtd/intremap.c    Fri Aug 06 18:35:02 2010 +0100
+++ b/xen/drivers/passthrough/vtd/intremap.c    Mon Aug 09 16:32:45 2010 +0100
@@ -444,10 +444,10 @@ void io_apic_write_remap_rte(
     }
 
     /* write new entry to ioapic */
+    *IO_APIC_BASE(apic) = reg + 1;
+    *(IO_APIC_BASE(apic)+4) = *(((u32 *)&old_rte)+1);
     *IO_APIC_BASE(apic) = reg;
     *(IO_APIC_BASE(apic)+4) = *(((u32 *)&old_rte)+0);
-    *IO_APIC_BASE(apic) = reg + 1;
-    *(IO_APIC_BASE(apic)+4) = *(((u32 *)&old_rte)+1);
 }
 
 #if defined(__i386__) || defined(__x86_64__)

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