[PATCH v2 1/4] iommu/vt-d: Block force-snoop domain attaching if no SC support

From: Lu Baolu
Date: Wed May 04 2022 - 21:10:18 EST


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@xxxxxxxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
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 cf43e8f9091b..d68f5bbf3e93 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4354,6 +4354,9 @@ 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