[PULL v3 13/31] virtio-iommu: Fix virtio_iommu_mr()

["Michael S. Tsirkin" <mst@redhat.com>]

From: Jean-Philippe Brucker <jean-philippe@linaro.org>

Due to an invalid mask, virtio_iommu_mr() may return the wrong memory
region. It hasn't been too problematic so far because the function was
only used to test existence of an endpoint, but that is about to change.

Fixes: cfb42188b24d ("virtio-iommu: Implement attach/detach command")
Cc: QEMU Stable <qemu-stable@nongnu.org>
Acked-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Message-Id: <20201030180510.747225-2-jean-philippe@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/virtio-iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
index 21ec63b108..4c8f3909b7 100644
--- a/hw/virtio/virtio-iommu.c
+++ b/hw/virtio/virtio-iommu.c
@@ -101,7 +101,7 @@ static IOMMUMemoryRegion *virtio_iommu_mr(VirtIOIOMMU *s, uint32_t sid)
     bus_n = PCI_BUS_NUM(sid);
     iommu_pci_bus = iommu_find_iommu_pcibus(s, bus_n);
     if (iommu_pci_bus) {
-        devfn = sid & PCI_DEVFN_MAX;
+        devfn = sid & (PCI_DEVFN_MAX - 1);
         dev = iommu_pci_bus->pbdev[devfn];
         if (dev) {
             return &dev->iommu_mr;
-- 
MST