[Qemu-devel] [PATCH for-2.5 02/15] s390x/pci : fix up s390 pci iommu translation function

[Cornelia Huck <cornelia.huck@de.ibm.com>]

From: Yi Min Zhao <zyimin@linux.vnet.ibm.com>

On s390x, each pci device has its own iommu, which is only properly
setup in qemu once the mpcifc instruction used to register the
translation table has been intercepted. Therefore, for a pci device that
is not configured or has not been initialized, proper translation is
neither required nor possible. Moreover, we may not have a host bridge
device ready yet.

This was exposed by a recent vfio change that triggers iommu translation
during the initialization of the vfio pci device. Let's do an early exit
in that case.

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Signed-off-by: Yi Min Zhao <zyimin@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/s390x/s390-pci-bus.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
index 560b66a..d5712ae 100644
--- a/hw/s390x/s390-pci-bus.c
+++ b/hw/s390x/s390-pci-bus.c
@@ -309,8 +309,7 @@ static IOMMUTLBEntry s390_translate_iommu(MemoryRegion *iommu, hwaddr addr,
     uint64_t pte;
     uint32_t flags;
     S390PCIBusDevice *pbdev = container_of(iommu, S390PCIBusDevice, mr);
-    S390pciState *s = S390_PCI_HOST_BRIDGE(pci_device_root_bus(pbdev->pdev)
-                                           ->qbus.parent);
+    S390pciState *s;
     IOMMUTLBEntry ret = {
         .target_as = &address_space_memory,
         .iova = 0,
@@ -319,8 +318,13 @@ static IOMMUTLBEntry s390_translate_iommu(MemoryRegion *iommu, hwaddr addr,
         .perm = IOMMU_NONE,
     };
 
+    if (!pbdev->configured || !pbdev->pdev) {
+        return ret;
+    }
+
     DPRINTF("iommu trans addr 0x%" PRIx64 "\n", addr);
 
+    s = S390_PCI_HOST_BRIDGE(pci_device_root_bus(pbdev->pdev)->qbus.parent);
     /* s390 does not have an APIC mapped to main storage so we use
      * a separate AddressSpace only for msix notifications
      */
-- 
2.6.3