iommu: Do not use IOMMU_DOMAIN_DMA if CONFIG_IOMMU_DMA is not enabled

msm_iommu platforms do not select either CONFIG_IOMMU_DMA or
CONFIG_ARM_DMA_USE_IOMMU so they create a IOMMU_DOMAIN_DMA domain by
default and never populate it. This acts like a BLOCKED domain and breaks
the GPU driver on the platform.

Detect this and force use of IDENTITY instead.

Fixes: 98ac73f ("iommu: Require a default_domain for all iommu drivers")
Reported-by: Dmitry Baryshkov <[email protected]>
Link: https://lore.kernel.org/linux-iommu/CAA8EJprz7VVmBG68U9zLuqPd0UdSRHYoLDJSP6tCj6H6qanuTQ@mail.gmail.com/
Signed-off-by: Jason Gunthorpe <[email protected]>
Reviewed-by: Jerry Snitselaar <[email protected]>
Tested-by: Dmitry Baryshkov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

Author: jgunthorpe

drivers/iommu/iommu.c

@@ -1920,6 +1920,18 @@ static int iommu_get_default_domain_type(struct iommu_group *group,
 		}
 	}
 
+	/*
+	 * If the common dma ops are not selected in kconfig then we cannot use
+	 * IOMMU_DOMAIN_DMA at all. Force IDENTITY if nothing else has been
+	 * selected.
+	 */
+	if (!IS_ENABLED(CONFIG_IOMMU_DMA)) {
+		if (WARN_ON(driver_type == IOMMU_DOMAIN_DMA))
+			return -1;
+		if (!driver_type)
+			driver_type = IOMMU_DOMAIN_IDENTITY;
+	}
+
 	if (untrusted) {
 		if (driver_type && driver_type != IOMMU_DOMAIN_DMA) {
 			dev_err_ratelimited(