[Xen-changelog] [xen-unstable] vt-d: Fix ioapic_rte_to_remap_entry error path.

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

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1281368025 -3600
# Node ID befd1814c0a262ce0d6c96727a76b907cdeecdc4
# Parent  add40eb478680b6f8de7102e87fba259f721ce1d
vt-d: Fix ioapic_rte_to_remap_entry error path.

When ioapic_rte_to_remap_entry fails, currently it just writes value
to ioapic. But the 'mask' bit may be changed if it writes to the upper
half of RTE. This patch ensures to recover the original value of 'mask'
bit in this case.

Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
---
 xen/drivers/passthrough/vtd/intremap.c |    7 +++++++
 1 files changed, 7 insertions(+)

diff -r add40eb47868 -r befd1814c0a2 xen/drivers/passthrough/vtd/intremap.c
--- a/xen/drivers/passthrough/vtd/intremap.c    Mon Aug 09 16:32:45 2010 +0100
+++ b/xen/drivers/passthrough/vtd/intremap.c    Mon Aug 09 16:33:45 2010 +0100
@@ -440,6 +440,13 @@ void io_apic_write_remap_rte(
     {
         *IO_APIC_BASE(apic) = rte_upper ? (reg + 1) : reg;
         *(IO_APIC_BASE(apic)+4) = value;
+
+        /* Recover the original value of 'mask' bit */
+        if ( rte_upper )
+        {
+            *IO_APIC_BASE(apic) = reg;
+            *(IO_APIC_BASE(apic)+4) = *(((u32 *)&old_rte)+0);
+        }
         return;
     }
 

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