iommu/vt-d: Block force-snoop domain attaching if no SC support

In the attach_dev callback of the default domain ops, if the domain has
been set force_snooping, but the iommu hardware of the device does not
support SC(Snoop Control) capability, the callback should block it and
return a corresponding error code.

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/20220510023407.2759143-6-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 f200af2..23985cb 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4333,6 +4333,9 @@ static int prepare_domain_attach_device(struct iommu_domain *domain,
        if (!iommu)
                return -ENODEV;
 
+       if (dmar_domain->force_snooping && !ecap_sc_support(iommu->ecap))
+               return -EOPNOTSUPP;
+
        /* check if this iommu agaw is sufficient for max mapped address */
        addr_width = agaw_to_width(iommu->agaw);
        if (addr_width > cap_mgaw(iommu->cap))