iommu/vt-d: Split paging_domain_compatible()

Make First/Second stage specific functions that follow the same pattern in
intel_iommu_domain_alloc_first/second_stage() for computing
EOPNOTSUPP. This makes the code easier to understand as if we couldn't
create a domain with the parameters for this IOMMU instance then we
certainly are not compatible with it.

Check superpage support directly against the per-stage cap bits and the
pgsize_bitmap.

Add a note that the force_snooping is read without locking. The locking
needs to cover the compatible check and the add of the device to the list.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/7-v3-dbbe6f7e7ae3+124ffe-vtd_prep_jgg@nvidia.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20250714045028.958850-10-baolu.lu@linux.intel.com
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index d2451a8ee6e7f8096c5fc77366d75a6a6f867489..3e774e3bb7355e8a55bbb9ec8a022be6fd59c647 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3431,33 +3431,75 @@ static void intel_iommu_domain_free(struct iommu_domain *domain)
        kfree(dmar_domain);
 }
 
+static int paging_domain_compatible_first_stage(struct dmar_domain *dmar_domain,
+                                               struct intel_iommu *iommu)
+{
+       if (WARN_ON(dmar_domain->domain.dirty_ops ||
+                   dmar_domain->nested_parent))
+               return -EINVAL;
+
+       /* Only SL is available in legacy mode */
+       if (!sm_supported(iommu) || !ecap_flts(iommu->ecap))
+               return -EINVAL;
+
+       /* Same page size support */
+       if (!cap_fl1gp_support(iommu->cap) &&
+           (dmar_domain->domain.pgsize_bitmap & SZ_1G))
+               return -EINVAL;
+       return 0;
+}
+
+static int
+paging_domain_compatible_second_stage(struct dmar_domain *dmar_domain,
+                                     struct intel_iommu *iommu)
+{
+       unsigned int sslps = cap_super_page_val(iommu->cap);
+
+       if (dmar_domain->domain.dirty_ops && !ssads_supported(iommu))
+               return -EINVAL;
+       if (dmar_domain->nested_parent && !nested_supported(iommu))
+               return -EINVAL;
+
+       /* Legacy mode always supports second stage */
+       if (sm_supported(iommu) && !ecap_slts(iommu->ecap))
+               return -EINVAL;
+
+       /* Same page size support */
+       if (!(sslps & BIT(0)) && (dmar_domain->domain.pgsize_bitmap & SZ_2M))
+               return -EINVAL;
+       if (!(sslps & BIT(1)) && (dmar_domain->domain.pgsize_bitmap & SZ_1G))
+               return -EINVAL;
+       return 0;
+}
+
 int paging_domain_compatible(struct iommu_domain *domain, struct device *dev)
 {
        struct device_domain_info *info = dev_iommu_priv_get(dev);
        struct dmar_domain *dmar_domain = to_dmar_domain(domain);
        struct intel_iommu *iommu = info->iommu;
+       int ret = -EINVAL;
        int addr_width;
 
-       if (WARN_ON_ONCE(!(domain->type & __IOMMU_DOMAIN_PAGING)))
-               return -EPERM;
+       if (intel_domain_is_fs_paging(dmar_domain))
+               ret = paging_domain_compatible_first_stage(dmar_domain, iommu);
+       else if (intel_domain_is_ss_paging(dmar_domain))
+               ret = paging_domain_compatible_second_stage(dmar_domain, iommu);
+       else if (WARN_ON(true))
+               ret = -EINVAL;
+       if (ret)
+               return ret;
 
+       /*
+        * FIXME this is locked wrong, it needs to be under the
+        * dmar_domain->lock
+        */
        if (dmar_domain->force_snooping && !ecap_sc_support(iommu->ecap))
                return -EINVAL;
 
-       if (domain->dirty_ops && !ssads_supported(iommu))
-               return -EINVAL;
-
        if (dmar_domain->iommu_coherency !=
                        iommu_paging_structure_coherency(iommu))
                return -EINVAL;
 
-       if (dmar_domain->iommu_superpage !=
-                       iommu_superpage_capability(iommu, dmar_domain->use_first_level))
-               return -EINVAL;
-
-       if (dmar_domain->use_first_level &&
-           (!sm_supported(iommu) || !ecap_flts(iommu->ecap)))
-               return -EINVAL;
 
        /* check if this iommu agaw is sufficient for max mapped address */
        addr_width = agaw_to_width(iommu->agaw);