[Xen-changelog] [xen-unstable] amd iommu: Fix a xen crash after pci-attach

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1297011241 0
# Node ID cba9a84d32fbf7d2d9f6ddd1fc1ab7dde8e290c1
# Parent  23f60ba52fffccd3916b643e0654209117765908
amd iommu: Fix a xen crash after pci-attach

pci-detach triggers IO page table deallocation if the last passthru
device has been removed from pdev list, and this will result a BUG on
amd systems for next pci-attach. This patch fixes this issue.

Signed-off-by: Wei Wang <wei.wang2@xxxxxxx>
---
 xen/drivers/passthrough/amd/pci_amd_iommu.c |    5 +++++
 1 files changed, 5 insertions(+)

diff -r 23f60ba52fff -r cba9a84d32fb xen/drivers/passthrough/amd/pci_amd_iommu.c
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c       Sun Feb 06 16:07:27 
2011 +0000
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c       Sun Feb 06 16:54:01 
2011 +0000
@@ -301,6 +301,11 @@ static int reassign_device( struct domai
     if ( target->max_pages > 0 )
         t->paging_mode = get_paging_mode(target->max_pages);
 
+    /* IO page tables might be destroyed after pci-detach the last device
+     * In this case, we have to re-allocate root table for next pci-attach.*/
+    if ( t->root_table == NULL )
+        allocate_domain_resources(t);
+
     amd_iommu_setup_domain_device(target, iommu, bdf);
     AMD_IOMMU_DEBUG("Re-assign %02x:%02x.%x from domain %d to domain %d\n",
                     bus, PCI_SLOT(devfn), PCI_FUNC(devfn),

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