Xen devel - Apr 2009 - [PATCH]Remove the BUG_ON in domain_context_mapping()

Remove the BUG_ON in domain_context_mapping().

Signed-off-by: Dexuan Cui <dexuan.cui@intel.com>

diff -r 655dc3bc1d8e xen/drivers/passthrough/vtd/iommu.c
--- a/xen/drivers/passthrough/vtd/iommu.c   Thu Apr 16 11:54:06 2009 +0100
+++ b/xen/drivers/passthrough/vtd/iommu.c   Thu Apr 16 12:03:27 2009 +0800
@@ -1196,7 +1196,20 @@ static int domain_context_mapping(struct
     u8 secbus, secdevfn;
     struct pci_dev *pdev = pci_get_pdev(bus, devfn);

-    BUG_ON(!pdev);
+    if ( pdev == NULL )
+    {
+        /* We can reach here by setup_dom0_rmrr() ->
iommu_prepare_rmrr_dev()
+         * -> domain_context_mapping().
+         * In the case a user enables VT-d and disables USB (that usually needs
+         * RMRR) in BIOS, we can''t discover the BDF of the USB
controller in
+         * setup_dom0_devices(), but the ACPI RMRR structures may still contain
+         * the BDF and at last pci_get_pdev() returns NULL here.
+         */
+        gdprintk(XENLOG_WARNING VTDPREFIX,
+                "domain_context_mapping: can''t find bdf =
%x:%x.%x\n",
+                 bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
+        return 0;
+    }

     drhd = acpi_find_matched_drhd_unit(pdev);
     if ( !drhd )
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