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@xxxxxxxxxx>
Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
Eric
> ---
> 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)
>
