Some devices manage I/O Page Faults (IOPF) themselves instead of relying
on PCIe PRI or Arm SMMU stall. Allow their drivers to enable SVA without
mandating IOMMU-managed IOPF. The other device drivers now need to first
enable IOMMU_DEV_FEAT_IOPF before enabling IOMMU_DEV_FEAT_SVA. Enabling
IOMMU_DEV_FEAT_IOPF on its own doesn't have any effect visible to the
device driver, it is used in combination with other features.
Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
---
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
Cc: Zhou Wang <wangzhou1@xxxxxxxxxxxxx>
---
include/linux/iommu.h | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index b7ea11fc1a93..00348e4c3c26 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -156,10 +156,24 @@ struct iommu_resv_region {
enum iommu_resv_type type;
};
-/* Per device IOMMU features */
+/**
+ * enum iommu_dev_features - Per device IOMMU features
+ * @IOMMU_DEV_FEAT_AUX: Auxiliary domain feature
+ * @IOMMU_DEV_FEAT_SVA: Shared Virtual Addresses
+ * @IOMMU_DEV_FEAT_IOPF: I/O Page Faults such as PRI or Stall. Generally
+ * enabling %IOMMU_DEV_FEAT_SVA requires
+ * %IOMMU_DEV_FEAT_IOPF, but some devices manage I/O Page
+ * Faults themselves instead of relying on the IOMMU. When
+ * supported, this feature must be enabled before and
+ * disabled after %IOMMU_DEV_FEAT_SVA.
+ *
+ * Device drivers query whether a feature is supported using
+ * iommu_dev_has_feature(), and enable it using iommu_dev_enable_feature().
+ */
enum iommu_dev_features {
- IOMMU_DEV_FEAT_AUX, /* Aux-domain feature */
- IOMMU_DEV_FEAT_SVA, /* Shared Virtual Addresses */
+ IOMMU_DEV_FEAT_AUX,
+ IOMMU_DEV_FEAT_SVA,
+ IOMMU_DEV_FEAT_IOPF,
};
#define IOMMU_PASID_INVALID (-1U)
--
2.30.0
