[Xen-changelog] [xen-unstable] AMD IOMMU: remove iommu tlb flush for non-present entries

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Wei Wang <wei.wang2@xxxxxxx>
# Date 1314004204 -3600
# Node ID 07f78b5bd03c02e32324eaa00487643d27b7ffa8
# Parent  c56dd5eb0fa2f6623cf198998373bbb24dd6142c
AMD IOMMU: remove iommu tlb flush for non-present entries

Fixes dom0 boot on some systems.

Signed-off-by: Wei Wang <wei.wang2@xxxxxxx>
---


diff -r c56dd5eb0fa2 -r 07f78b5bd03c xen/drivers/passthrough/amd/iommu_map.c
--- a/xen/drivers/passthrough/amd/iommu_map.c   Mon Aug 22 10:05:27 2011 +0100
+++ b/xen/drivers/passthrough/amd/iommu_map.c   Mon Aug 22 10:10:04 2011 +0100
@@ -796,7 +796,10 @@
     if ( !need_flush )
         goto out;
 
-    amd_iommu_flush_pages(d, gfn, 0);
+    /* 4K mapping for PV guests never changes, 
+     * no need to flush if we trust non-present bits */
+    if ( is_hvm_domain(d) )
+        amd_iommu_flush_pages(d, gfn, 0);
 
     for ( merge_level = IOMMU_PAGING_MODE_LEVEL_2;
           merge_level <= hd->paging_mode; merge_level++ )

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