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.
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
drivers/iommu/amd/iommu.c | 2 ++
drivers/iommu/intel/iommu.c | 4 ++++
include/linux/iommu.h | 5 +++++
3 files changed, 11 insertions(+)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index d3b39d0416fa32..d0802cab2a2f0c 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2286,6 +2286,8 @@ 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 48cdcd0a5cf346..438ba997fa230e 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4458,7 +4458,11 @@ static bool intel_iommu_capable(struct device *dev, enum iommu_cap cap)
return irq_remapping_enabled == 1;
if (cap == IOMMU_CAP_PRE_BOOT_PROTECTION)
return dmar_platform_optin();
+ if (cap == IOMMU_CAP_ENFORCE_CACHE_COHERENCY) {
+ struct device_domain_info *info = dev_iommu_priv_get(dev);
+ return ecap_sc_support(info->iommu->ecap);
+ }
return false;
}
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 3c9da1f8979e3a..40cf2d8393465f 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -108,6 +108,11 @@ 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 */
--
2.38.0
