Re: [PATCH v4 0/6] Define EINVAL as device/domain incompatibility

Re: [PATCH v4 0/6] Define EINVAL as device/domain incompatibility

[Jean-Philippe Brucker]

On Wed, Sep 21, 2022 at 01:22:31AM -0700, Nicolin Chen wrote:
> This series is to replace the previous EMEDIUMTYPE patch in a VFIO series:
> https://lore.kernel.org/kvm/Yxnt9uQTmbqul5lf@8bytes.org/
> 
> The purpose is to regulate all existing ->attach_dev callback functions to
> use EINVAL exclusively for an incompatibility error between a device and a
> domain. This allows VFIO and IOMMUFD to detect such a soft error, and then
> try a different domain with the same device.
[...]
>  drivers/iommu/amd/iommu.c                   | 12 +----
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 11 +---
>  drivers/iommu/arm/arm-smmu/arm-smmu.c       |  3 --
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c     |  7 +--
>  drivers/iommu/fsl_pamu.c                    |  2 +-
>  drivers/iommu/fsl_pamu_domain.c             |  4 +-
>  drivers/iommu/intel/iommu.c                 | 10 ++--
>  drivers/iommu/intel/pasid.c                 |  6 ++-
>  drivers/iommu/iommu.c                       | 22 ++++++++
>  drivers/iommu/ipmmu-vmsa.c                  |  2 -
>  drivers/iommu/msm_iommu.c                   | 59 +++++++++++----------
>  drivers/iommu/mtk_iommu.c                   |  4 +-
>  drivers/iommu/omap-iommu.c                  |  6 +--
>  drivers/iommu/sprd-iommu.c                  |  4 +-
>  drivers/iommu/tegra-gart.c                  |  2 +-
>  drivers/iommu/virtio-iommu.c                |  7 ++-

For virtio-iommu:

Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

>  include/linux/iommu.h                       | 12 +++++
>  17 files changed, 90 insertions(+), 83 deletions(-)
> 
> -- 
> 2.17.1
> 
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RE: [PATCH v4 3/6] iommu: Add return value rules to attach_dev op and APIs

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Wednesday, September 21, 2022 4:23 PM
> 
> 
> +/**
> + * iommu_attach_device - Attach a device to an IOMMU domain
> + * @domain: IOMMU domain to attach
> + * @dev: Device that will be attached
> + *
> + * Returns 0 on success and error code on failure
> + *
> + * Note that EINVAL may be returned as a soft failure if the domain and
> device
> + * are incompatible due to some previous configuration of the domain, in
> which
> + * case attaching the same device to a different domain may succeed.

Revise a bit:

 * Note that EINVAL can be treated as a soft failure, indicating
 * that certain configuration of the domain is incompatible with
 * the device. In this case attaching a different domain to the
 * device may succeed.

Apart from that:

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
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RE: [PATCH v4 5/6] iommu: Use EINVAL for incompatible device/domain in ->attach_dev

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Wednesday, September 21, 2022 4:24 PM
> 
> Following the new rules in include/linux/iommu.h kdocs, update all drivers
> ->attach_dev callback functions to return EINVAL in the failure paths that
> are related to domain incompatibility.
> 
> Also, drop adjacent error prints to prevent a kernel log spam.
> 
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
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