Hi Thomas,

On 2020/11/13 3:15, Thomas Gleixner wrote:
The recent changes to store the MSI irqdomain pointer in struct device
missed that Intel DMAR does not register virtual function devices.  Due to
that a VF device gets the plain PCI-MSI domain assigned and then issues
compat MSI messages which get caught by the interrupt remapping unit.

Cure that by inheriting the irq domain from the physical function

That's a temporary workaround. The correct fix is to inherit the irq domain
from the bus, but that's a larger effort which needs quite some other
changes to the way how x86 manages PCI and MSI domains.

Fixes: 85a8dfc57a0b ("iommm/vt-d: Store irq domain in struct device")
Reported-by: Jason Gunthorpe <j...@nvidia.com>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
  drivers/iommu/intel/dmar.c |   19 ++++++++++++++++++-
  1 file changed, 18 insertions(+), 1 deletion(-)

--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -333,6 +333,11 @@ static void  dmar_pci_bus_del_dev(struct
+static inline void vf_inherit_msi_domain(struct pci_dev *pdev)
+       dev_set_msi_domain(&pdev->dev, dev_get_msi_domain(&pdev->physfn->dev));
  static int dmar_pci_bus_notifier(struct notifier_block *nb,
                                 unsigned long action, void *data)
@@ -342,8 +347,20 @@ static int dmar_pci_bus_notifier(struct
        /* Only care about add/remove events for physical functions.
         * For VFs we actually do the lookup based on the corresponding
         * PF in device_to_iommu() anyway. */
-       if (pdev->is_virtfn)
+       if (pdev->is_virtfn) {
+               /*
+                * Note: This is a horrible hack and needs to be cleaned
+                * up by assigning the domain to the bus, but that's too
+                * big of a change for post rc3.
+                *
+                * Ensure that the VF device inherits the irq domain of the
+                * PF device:
+                */
+               if (action == BUS_NOTIFY_ADD_DEVICE)
+                       vf_inherit_msi_domain(pdev);
                return NOTIFY_DONE;
+       }
        if (action != BUS_NOTIFY_ADD_DEVICE &&
            action != BUS_NOTIFY_REMOVED_DEVICE)
                return NOTIFY_DONE;

We also encountered this problem in internal testing. This patch can
solve the problem.

Acked-by: Lu Baolu <baolu...@linux.intel.com>

Best regards,
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