Re: [PATCH v12 03/10] iommu: Separate IOMMU_DEV_FEAT_IOPF from IOMMU_DEV_FEAT_SVA

[Auger Eric]

Hi Jean,

On 1/27/21 4:43 PM, Jean-Philippe Brucker wrote:
> 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 
Reviewed-by: Eric Auger 

Eric

> ---
> Cc: Arnd Bergmann 
> Cc: David Woodhouse 
> Cc: Greg Kroah-Hartman 
> Cc: Joerg Roedel 
> Cc: Lu Baolu 
> Cc: Will Deacon 
> Cc: Zhangfei Gao 
> Cc: Zhou Wang 
> ---
>  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_typetype;
>  };
>  
> -/* 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)
> 

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[PATCH v12 03/10] iommu: Separate IOMMU_DEV_FEAT_IOPF from IOMMU_DEV_FEAT_SVA

[Jean-Philippe Brucker]

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 
---
Cc: Arnd Bergmann 
Cc: David Woodhouse 
Cc: Greg Kroah-Hartman 
Cc: Joerg Roedel 
Cc: Lu Baolu 
Cc: Will Deacon 
Cc: Zhangfei Gao 
Cc: Zhou Wang 
---
 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_typetype;
 };
 
-/* 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

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