On Tue, Oct 03, 2023 at 12:21:59AM +0300, Dmitry Baryshkov wrote:

On Wed, 13 Sept 2023 at 16:45, Jason Gunthorpe [off-list ref] wrote:

quoted

At this point every iommu driver will cause a default_domain to be
selected, so we can finally remove this gap from the core code.

The following table explains what each driver supports and what the
resulting default_domain will be:

                                        ops->defaut_domain
                    IDENTITY   DMA  PLATFORM    v      ARM32          dma-iommu  ARCH
amd/iommu.c             Y       Y                       N/A             either
apple-dart.c            Y       Y                       N/A             either
arm-smmu.c              Y       Y                       IDENTITY        either
qcom_iommu.c            G       Y                       IDENTITY        either
arm-smmu-v3.c           Y       Y                       N/A             either
exynos-iommu.c          G       Y                       IDENTITY        either
fsl_pamu_domain.c                       Y       Y       N/A             N/A     PLATFORM
intel/iommu.c           Y       Y                       N/A             either
ipmmu-vmsa.c            G       Y                       IDENTITY        either
msm_iommu.c             G                               IDENTITY        N/A

Unfortunately this patch breaks msm_iommu platforms. This driver
doesn't select ARM_DMA_USE_IOMMU, so iommu_get_default_domain_type()
returns 0, bus_iommu_probe() fails with -ENODEV.
If I make MSM_IOMMU select ARM_DMA_USE_IOMMU, then GPU probing fails
with -EBUSY.

Oh, OK.

Does this fix it?

diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c
index cdc7b730192a35..f7ef081c33dcb2 100644
--- a/drivers/iommu/msm_iommu.c
+++ b/drivers/iommu/msm_iommu.c

@@ -685,10 +685,16 @@ irqreturn_t msm_iommu_fault_handler(int irq, void *dev_id)
 	return 0;
 }
 
+static int msm_iommu_def_domain_type(struct device *dev)
+{
+	return IOMMU_DOMAIN_IDENTITY;
+}
+
 static struct iommu_ops msm_iommu_ops = {
 	.identity_domain = &msm_iommu_identity_domain,
 	.domain_alloc_paging = msm_iommu_domain_alloc_paging,
 	.probe_device = msm_iommu_probe_device,
+	.def_domain_type = msm_iommu_def_domain_type,
 	.device_group = generic_device_group,
 	.pgsize_bitmap = MSM_IOMMU_PGSIZES,
 	.of_xlate = qcom_iommu_of_xlate,