[PATCH v4 01/17] iommu: Add IOMMU_CAP_ENFORCE_CACHE_COHERENCY

Jason Gunthorpe
2022-11-08T00:49:17Z

This queries if a domain linked to a device should expect to support
enforce_cache_coherency() so iommufd can negotiate the rules for when a
domain should be shared or not.

For iommufd a device that declares IOMMU_CAP_ENFORCE_CACHE_COHERENCY will
not be attached to a domain that does not support it.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/iommu/amd/iommu.c | 2 ++
drivers/iommu/intel/iommu.c | 16 +++++++++++-----
include/linux/iommu.h | 5 +++++
3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 45299eb7e8e306..240c535e317cc7 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2278,6 +2278,8 @@ static bool amd_iommu_capable(struct device *dev, enum iommu_cap cap)
return false;
case IOMMU_CAP_PRE_BOOT_PROTECTION:
return amdr_ivrs_remap_support;
+ case IOMMU_CAP_ENFORCE_CACHE_COHERENCY:
+ return true;
default:
break;
}
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index f298e51d5aa67a..157c9727411076 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4450,14 +4450,20 @@ static bool intel_iommu_enforce_cache_coherency(struct iommu_domain *domain)

static bool intel_iommu_capable(struct device *dev, enum iommu_cap cap)
{
- if (cap == IOMMU_CAP_CACHE_COHERENCY)
+ struct device_domain_info *info = dev_iommu_priv_get(dev);
+
+ switch (cap) {
+ case IOMMU_CAP_CACHE_COHERENCY:
return true;
- if (cap == IOMMU_CAP_INTR_REMAP)
+ case IOMMU_CAP_INTR_REMAP:
return irq_remapping_enabled == 1;
- if (cap == IOMMU_CAP_PRE_BOOT_PROTECTION)
+ case IOMMU_CAP_PRE_BOOT_PROTECTION:
return dmar_platform_optin();
-
- return false;
+ case IOMMU_CAP_ENFORCE_CACHE_COHERENCY:
+ return ecap_sc_support(info->iommu->ecap);
+ default:
+ return false;
+ }
}

static struct iommu_device *intel_iommu_probe_device(struct device *dev)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 68d7d304cdb761..a09fd32d8cc273 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -124,6 +124,11 @@ enum iommu_cap {
IOMMU_CAP_NOEXEC, /* IOMMU_NOEXEC flag */
IOMMU_CAP_PRE_BOOT_PROTECTION, /* Firmware says it used the IOMMU for
DMA protection and we should too */
+ /*
+ * Per-device flag indicating if enforce_cache_coherency() will work on
+ * this device.
+ */
+ IOMMU_CAP_ENFORCE_CACHE_COHERENCY,
};

/* These are the possible reserved region types */
--
2.38.1