vfio: Remove VFIO_TYPE1_NESTING_IOMMU

This control causes the ARM SMMU drivers to choose a stage 2
implementation for the IO pagetable (vs the stage 1 usual default),
however this choice has no significant visible impact to the VFIO
user. Further qemu never implemented this and no other userspace user is
known.

The original description in commit f5c9ecebaf2a ("vfio/iommu_type1: add
new VFIO_TYPE1_NESTING_IOMMU IOMMU type") suggested this was to "provide
SMMU translation services to the guest operating system" however the rest
of the API to set the guest table pointer for the stage 1 and manage
invalidation was never completed, or at least never upstreamed, rendering
this part useless dead code.

Upstream has now settled on iommufd as the uAPI for controlling nested
translation. Choosing the stage 2 implementation should be done by through
the IOMMU_HWPT_ALLOC_NEST_PARENT flag during domain allocation.

Remove VFIO_TYPE1_NESTING_IOMMU and everything under it including the
enable_nesting iommu_domain_op.

Just in-case there is some userspace using this continue to treat
requesting it as a NOP, but do not advertise support any more.

Acked-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Mostafa Saleh <smostafa@google.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Donald Dutile <ddutile@redhat.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/1-v4-9e99b76f3518+3a8-smmuv3_nesting_jgg@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>

2 files changed, 0 insertions, 32 deletions

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 737c5b882355..acf250aeb18b 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -3378,21 +3378,6 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev)
 	return group;
 }
 
-static int arm_smmu_enable_nesting(struct iommu_domain *domain)
-{
-	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
-	int ret = 0;
-
-	mutex_lock(&smmu_domain->init_mutex);
-	if (smmu_domain->smmu)
-		ret = -EPERM;
-	else
-		smmu_domain->stage = ARM_SMMU_DOMAIN_S2;
-	mutex_unlock(&smmu_domain->init_mutex);
-
-	return ret;
-}
-
 static int arm_smmu_of_xlate(struct device *dev,
 			     const struct of_phandle_args *args)
 {
@@ -3514,7 +3499,6 @@ static struct iommu_ops arm_smmu_ops = {
 		.flush_iotlb_all	= arm_smmu_flush_iotlb_all,
 		.iotlb_sync		= arm_smmu_iotlb_sync,
 		.iova_to_phys		= arm_smmu_iova_to_phys,
-		.enable_nesting		= arm_smmu_enable_nesting,
 		.free			= arm_smmu_domain_free_paging,
 	}
 };
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 8321962b3714..12b173eec454 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1558,21 +1558,6 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev)
 	return group;
 }
 
-static int arm_smmu_enable_nesting(struct iommu_domain *domain)
-{
-	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
-	int ret = 0;
-
-	mutex_lock(&smmu_domain->init_mutex);
-	if (smmu_domain->smmu)
-		ret = -EPERM;
-	else
-		smmu_domain->stage = ARM_SMMU_DOMAIN_NESTED;
-	mutex_unlock(&smmu_domain->init_mutex);
-
-	return ret;
-}
-
 static int arm_smmu_set_pgtable_quirks(struct iommu_domain *domain,
 		unsigned long quirks)
 {
@@ -1656,7 +1641,6 @@ static struct iommu_ops arm_smmu_ops = {
 		.flush_iotlb_all	= arm_smmu_flush_iotlb_all,
 		.iotlb_sync		= arm_smmu_iotlb_sync,
 		.iova_to_phys		= arm_smmu_iova_to_phys,
-		.enable_nesting		= arm_smmu_enable_nesting,
 		.set_pgtable_quirks	= arm_smmu_set_pgtable_quirks,
 		.free			= arm_smmu_domain_free,
 	}