[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 <jean-philippe at linaro.org>
Reviewed-by: Eric Auger <eric.auger at redhat.com>

Eric

> ---
> Cc: Arnd Bergmann <arnd at arndb.de>
> Cc: David Woodhouse <dwmw2 at infradead.org>
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Cc: Joerg Roedel <joro at 8bytes.org>
> Cc: Lu Baolu <baolu.lu at linux.intel.com>
> Cc: Will Deacon <will at kernel.org>
> Cc: Zhangfei Gao <zhangfei.gao at linaro.org>
> Cc: Zhou Wang <wangzhou1 at hisilicon.com>
> ---
>  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)
>