iommufd: Make sw_msi_start a group global

The sw_msi_start is only set by the ARM drivers and it is always constant.
Due to the way vfio/iommufd allow domains to be re-used between
devices we have a built in assumption that there is only one value
for sw_msi_start and it is global to the system.

To make replace simpler where we may not reparse the
iommu_get_resv_regions() move the sw_msi_start to the iommufd_group so it
is always available once any HWPT has been attached.

Link: https://lore.kernel.org/r/7-v8-6659224517ea+532-iommufd_alloc_jgg@nvidia.comReviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/iommu/iommufd/device.c

@@ -88,6 +88,7 @@ static struct iommufd_group *iommufd_get_group(struct iommufd_ctx *ictx,
 	kref_init(&new_igroup->ref);
 	mutex_init(&new_igroup->lock);
 	INIT_LIST_HEAD(&new_igroup->device_list);
+	new_igroup->sw_msi_start = PHYS_ADDR_MAX;
 	/* group reference moves into new_igroup */
 	new_igroup->group = group;
 
@@ -292,10 +293,10 @@ u32 iommufd_device_to_id(struct iommufd_device *idev)
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_device_to_id, IOMMUFD);
 
-static int iommufd_device_setup_msi(struct iommufd_device *idev,
-				    struct iommufd_hw_pagetable *hwpt,
-				    phys_addr_t sw_msi_start)
+static int iommufd_group_setup_msi(struct iommufd_group *igroup,
+				   struct iommufd_hw_pagetable *hwpt)
 {
+	phys_addr_t sw_msi_start = igroup->sw_msi_start;
 	int rc;
 
 	/*
@@ -328,7 +329,6 @@ static int iommufd_device_setup_msi(struct iommufd_device *idev,
 int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 				struct iommufd_device *idev)
 {
-	phys_addr_t sw_msi_start = PHYS_ADDR_MAX;
 	int rc;
 
 	mutex_lock(&idev->igroup->lock);
@@ -356,8 +356,8 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 		}
 	}
 
-	rc = iopt_table_enforce_dev_resv_regions(
-		&hwpt->ioas->iopt, idev->dev, &sw_msi_start);
+	rc = iopt_table_enforce_dev_resv_regions(&hwpt->ioas->iopt, idev->dev,
+						 &idev->igroup->sw_msi_start);
 	if (rc)
 		goto err_unlock;
 
@@ -369,7 +369,7 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 	 * attachment.
 	 */
 	if (list_empty(&idev->igroup->device_list)) {
-		rc = iommufd_device_setup_msi(idev, hwpt, sw_msi_start);
+		rc = iommufd_group_setup_msi(idev->igroup, hwpt);
 		if (rc)
 			goto err_unresv;
 

drivers/iommu/iommufd/iommufd_private.h

@@ -267,6 +267,7 @@ struct iommufd_group {
 	struct iommu_group *group;
 	struct iommufd_hw_pagetable *hwpt;
 	struct list_head device_list;
+	phys_addr_t sw_msi_start;
 };
 
 /*