iommm/amd: Store irq domain in struct device

As the next step to make X86 utilize the direct MSI irq domain operations
store the irq domain pointer in the device struct when a device is probed.

It only overrides the irqdomain of devices which are handled by a regular
PCI/MSI irq domain which protects PCI devices behind special busses like
VMD which have their own irq domain.

No functional change.

It just avoids the redirection through arch_*_msi_irqs() and allows the
PCI/MSI core to directly invoke the irq domain alloc/free functions instead
of having to look up the irq domain for every single MSI interupt.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20200826112333.806328762@linutronix.de

drivers/iommu/amd/iommu.c

@@ -729,7 +729,21 @@ static void iommu_poll_ga_log(struct amd_iommu *iommu)
 		}
 	}
 }
-#endif /* CONFIG_IRQ_REMAP */
+
+static void
+amd_iommu_set_pci_msi_domain(struct device *dev, struct amd_iommu *iommu)
+{
+	if (!irq_remapping_enabled || !dev_is_pci(dev) ||
+	    pci_dev_has_special_msi_domain(to_pci_dev(dev)))
+		return;
+
+	dev_set_msi_domain(dev, iommu->msi_domain);
+}
+
+#else /* CONFIG_IRQ_REMAP */
+static inline void
+amd_iommu_set_pci_msi_domain(struct device *dev, struct amd_iommu *iommu) { }
+#endif /* !CONFIG_IRQ_REMAP */
 
 #define AMD_IOMMU_INT_MASK	\
 	(MMIO_STATUS_EVT_INT_MASK | \
@@ -2157,6 +2171,7 @@ static struct iommu_device *amd_iommu_probe_device(struct device *dev)
 		iommu_dev = ERR_PTR(ret);
 		iommu_ignore_device(dev);
 	} else {
+		amd_iommu_set_pci_msi_domain(dev, iommu);
 		iommu_dev = &iommu->iommu;
 	}