[Xen-devel] Comments on Xen bug 1732

[Haitao Shan <maillists.shan@xxxxxxxxx>]

Hi, Jan,

As you may already notice the bug 1732, (http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1732), the culprit is c/s 22182.

I see the following attached code in your patch. It is pointless to check msi->table_base against the value read from physical device if this function is a virtual function of SR-IOV device. VFs are required to have BARs zeroed by specifications. And for VFs, unless you can read these values from corresponding PF, you will have to trust the "table_base" passed from dom0 via hypercall. Actually, this parameter is specifically introduced for enabling SR-IOV.

I am not familiar with this patch and hence its story. But I think it would be very simple for you to fix this up?

BTW: I vaguely recall that MSI-X table base might not be the first page of the corresponding BAR register.

Shan Haitao

+    if ( !dev->msix_nr_entries )

+    {

+        u64 pba_paddr;

+        u32 pba_offset;

+

+        ASSERT(!dev->msix_used_entries);

+        WARN_ON(msi->table_base != read_pci_mem_bar(bus, slot, func, bir));

+

+        dev->msix_nr_entries = nr_entries;

+        dev->msix_table.first = PFN_DOWN(table_paddr);

+        dev->msix_table.last = PFN_DOWN(table_paddr +

+                                        nr_entries * PCI_MSIX_ENTRY_SIZE - 1);

+        WARN_ON(rangeset_overlaps_range(mmio_ro_ranges, dev->msix_table.first,

+                                        dev->msix_table.last));

+

+        pba_offset = pci_conf_read32(bus, slot, func,

+                                     msix_pba_offset_reg(pos));

+        bir = (u8)(pba_offset & PCI_MSIX_BIRMASK);

+        pba_paddr = read_pci_mem_bar(bus, slot, func, bir);

+        WARN_ON(!pba_paddr);

+        pba_paddr += pba_offset & ~PCI_MSIX_BIRMASK;

+

+        dev->msix_pba.first = PFN_DOWN(pba_paddr);

+        dev->msix_pba.last = PFN_DOWN(pba_paddr +

+                                      BITS_TO_LONGS(nr_entries) - 1);

+        WARN_ON(rangeset_overlaps_range(mmio_ro_ranges, dev->msix_pba.first,

+                                        dev->msix_pba.last));

+

+        if ( rangeset_add_range(mmio_ro_ranges, dev->msix_table.first,

+                                dev->msix_table.last) )

+            WARN();

+        if ( rangeset_add_range(mmio_ro_ranges, dev->msix_pba.first,

+                                dev->msix_pba.last) )

+            WARN();

+

+        if ( dev->domain )

+            p2m_change_entry_type_global(p2m_get_hostp2m(dev->domain),

+                                         p2m_mmio_direct, p2m_mmio_direct);

+        if ( !dev->domain || !paging_mode_translate(dev->domain) )

+        {

+            struct domain *d = dev->domain;

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