[PATCH v4 1/4] iommu/vt-d: Block force-snoop domain attaching if no SC support

Lu Baolu
2022-05-08T12:38:42Z

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>
---
drivers/iommu/intel/iommu.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 2990f80c5e08..b4802f4055a0 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4367,6 +4367,9 @@ 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))
--
2.25.1