vfio/type1: Check MSI remapping at irq domain level

In case the IOMMU translates MSI transactions (typical case
on ARM), we check MSI remapping capability at IRQ domain
level. Otherwise it is checked at IOMMU level.

At this stage the arm-smmu-(v3) still advertise the
IOMMU_CAP_INTR_REMAP capability at IOMMU level. This will be
removed in subsequent patches.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Tomasz Nowicki <tomasz.nowicki@caviumnetworks.com>
Tested-by: Tomasz Nowicki <tomasz.nowicki@caviumnetworks.com>
Tested-by: Bharat Bhushan <bharat.bhushan@nxp.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

drivers/vfio/vfio_iommu_type1.c

@@ -40,6 +40,7 @@
 #include <linux/mdev.h>
 #include <linux/notifier.h>
 #include <linux/dma-iommu.h>
+#include <linux/irqdomain.h>
 
 #define DRIVER_VERSION  "0.2"
 #define DRIVER_AUTHOR   "Alex Williamson <alex.williamson@redhat.com>"
@@ -1212,7 +1213,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 	struct vfio_domain *domain, *d;
 	struct bus_type *bus = NULL, *mdev_bus;
 	int ret;
-	bool resv_msi;
+	bool resv_msi, msi_remap;
 	phys_addr_t resv_msi_base;
 
 	mutex_lock(&iommu->lock);
@@ -1288,8 +1289,10 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 	INIT_LIST_HEAD(&domain->group_list);
 	list_add(&group->next, &domain->group_list);
 
-	if (!allow_unsafe_interrupts &&
-	    !iommu_capable(bus, IOMMU_CAP_INTR_REMAP)) {
+	msi_remap = resv_msi ? irq_domain_check_msi_remap() :
+				iommu_capable(bus, IOMMU_CAP_INTR_REMAP);
+
+	if (!allow_unsafe_interrupts && !msi_remap) {
 		pr_warn("%s: No interrupt remapping support.  Use the module param \"allow_unsafe_interrupts\" to enable VFIO IOMMU support on this platform\n",
 		       __func__);
 		ret = -EPERM;