[xen staging-4.14] pci: cleanup MSI interrupts before removing device from IOMMU

[patchbot@xxxxxxx]

commit 898864c3736338548bc2f684b7e307326e0dd4a5
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Wed Nov 4 11:01:27 2020 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Nov 4 11:01:27 2020 +0100

    pci: cleanup MSI interrupts before removing device from IOMMU
    
    Doing the MSI cleanup after removing the device from the IOMMU leads
    to the following panic on AMD hardware:
    
    Assertion 'table.ptr && (index < intremap_table_entries(table.ptr, iommu))' 
failed at iommu_intr.c:172
    ----[ Xen-4.13.1-10.0.3-d  x86_64  debug=y   Not tainted ]----
    CPU:    3
    RIP:    e008:[<ffff82d08026ae3c>] 
drivers/passthrough/amd/iommu_intr.c#get_intremap_entry+0x52/0x7b
    [...]
    Xen call trace:
       [<ffff82d08026ae3c>] R 
drivers/passthrough/amd/iommu_intr.c#get_intremap_entry+0x52/0x7b
       [<ffff82d08026af25>] F 
drivers/passthrough/amd/iommu_intr.c#update_intremap_entry_from_msi_msg+0xc0/0x342
       [<ffff82d08026ba65>] F amd_iommu_msi_msg_update_ire+0x98/0x129
       [<ffff82d08025dd36>] F iommu_update_ire_from_msi+0x1e/0x21
       [<ffff82d080286862>] F msi_free_irq+0x55/0x1a0
       [<ffff82d080286f25>] F pci_cleanup_msi+0x8c/0xb0
       [<ffff82d08025cf52>] F pci_remove_device+0x1af/0x2da
       [<ffff82d0802a42d1>] F do_physdev_op+0xd18/0x1187
       [<ffff82d080383925>] F pv_hypercall+0x1f5/0x567
       [<ffff82d08038a432>] F lstar_enter+0x112/0x120
    
    That's because the call to iommu_remove_device on AMD hardware will
    remove the per-device interrupt remapping table, and hence the call to
    pci_cleanup_msi done afterwards will find a null intremap table and
    crash.
    
    Reorder the calls so that MSI interrupts are torn down before removing
    the device from the IOMMU.
    
    Fixes: d7cfeb7c13ed ("AMD/IOMMU: don't blindly allocate interrupt remapping 
tables")
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 710f62cc826bb8c7ead99f9d6b6b269e39ff3e98
    master date: 2020-10-23 10:13:14 +0200
---
 xen/drivers/passthrough/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index 5846978890..2d6238a5bb 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -843,10 +843,10 @@ int pci_remove_device(u16 seg, u8 bus, u8 devfn)
     list_for_each_entry ( pdev, &pseg->alldevs_list, alldevs_list )
         if ( pdev->bus == bus && pdev->devfn == devfn )
         {
+            pci_cleanup_msi(pdev);
             ret = iommu_remove_device(pdev);
             if ( pdev->domain )
                 list_del(&pdev->domain_list);
-            pci_cleanup_msi(pdev);
             free_pdev(pseg, pdev);
             printk(XENLOG_DEBUG "PCI remove device %04x:%02x:%02x.%u\n",
                    seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
--
generated by git-patchbot for /home/xen/git/xen.git#staging-4.14