iommu/vt-d: Remove domain_update_iommu_snooping()

The IOMMU force snooping capability is not required to be consistent
among all the IOMMUs anymore. Remove force snooping capability check
in the IOMMU hot-add path and domain_update_iommu_snooping() becomes
a dead code now.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220508123525.1973626-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20220510023407.2759143-8-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index f366e8c4963654a432f9d3849e53c6124d898c69..985a83e242447bc6cf8dabc7bed81897bb03cf78 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -533,33 +533,6 @@ static void domain_update_iommu_coherency(struct dmar_domain *domain)
        rcu_read_unlock();
 }
 
-static bool domain_update_iommu_snooping(struct intel_iommu *skip)
-{
-       struct dmar_drhd_unit *drhd;
-       struct intel_iommu *iommu;
-       bool ret = true;
-
-       rcu_read_lock();
-       for_each_active_iommu(iommu, drhd) {
-               if (iommu != skip) {
-                       /*
-                        * If the hardware is operating in the scalable mode,
-                        * the snooping control is always supported since we
-                        * always set PASID-table-entry.PGSNP bit if the domain
-                        * is managed outside (UNMANAGED).
-                        */
-                       if (!sm_supported(iommu) &&
-                           !ecap_sc_support(iommu->ecap)) {
-                               ret = false;
-                               break;
-                       }
-               }
-       }
-       rcu_read_unlock();
-
-       return ret;
-}
-
 static int domain_update_iommu_superpage(struct dmar_domain *domain,
                                         struct intel_iommu *skip)
 {
@@ -3572,12 +3545,7 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
                        iommu->name);
                return -ENXIO;
        }
-       if (!ecap_sc_support(iommu->ecap) &&
-           domain_update_iommu_snooping(iommu)) {
-               pr_warn("%s: Doesn't support snooping.\n",
-                       iommu->name);
-               return -ENXIO;
-       }
+
        sp = domain_update_iommu_superpage(NULL, iommu) - 1;
        if (sp >= 0 && !(cap_super_page_val(iommu->cap) & (1 << sp))) {
                pr_warn("%s: Doesn't support large page.\n",