File 18870-vtd-flush-per-device.patch of Package xen

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1228474781 0
# Node ID 99f01b8184c7c16f612731e2a525687dc8d424dc
# Parent  09160c3bd1797fdee111c2837f26a749e0bf9435
VT-d code cleanup

This patch narrow context caching flush range from the
domain-selective to the device-selective, when unmapping a device.

Signed-off-by: Yu Zhao <yu.zhao@intel.com>

--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1323,7 +1323,9 @@ static int domain_context_unmap_one(
     context_clear_entry(*context);
     iommu_flush_cache_entry(context);
 
-    if ( iommu_flush_context_domain(iommu, domain_iommu_domid(domain), 0) )
+    if ( iommu_flush_context_device(iommu, domain_iommu_domid(domain),
+                                    (((u16)bus) << 8) | devfn,
+                                    DMA_CCMD_MASK_NOBIT, 0) )
         iommu_flush_write_buffer(iommu);
     else
         iommu_flush_iotlb_dsi(iommu, domain_iommu_domid(domain), 0);