Re: [PATCH v8 12/14] iommu/arm-smmu-v3: Introduce struct arm_smmu_vmaster

[Will Deacon <will@kernel.org>]

On Tue, Feb 25, 2025 at 09:25:40AM -0800, Nicolin Chen wrote:
> Use it to store all vSMMU-related data. The vsid (Virtual Stream ID) will
> be the first use case. Since the vsid reader will be the eventq handler
> that already holds a streams_mutex, reuse that to fenche the vmaster too.

"fenche"?

> Also add a pair of arm_smmu_attach_prepare/commit_vmaster helpers to set
> or unset the master->vmaster point. Put these helpers inside the existing

s/point/pointer/

> arm_smmu_attach_prepare/commit().
> 
> For identity/blocked ops that don't call arm_smmu_attach_prepare/commit(),
> add a simpler arm_smmu_master_clear_vmaster helper to unset the vmaster.
> 
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Reviewed-by: Pranjal Shrivastavat <praan@google.com>

(per Pranjal: please fix his mis-spelling of his own name here and in
the other patches too!)

> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   | 28 ++++++++++++
>  .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c     | 45 +++++++++++++++++++
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 18 +++++++-
>  3 files changed, 90 insertions(+), 1 deletion(-)

[...]

> @@ -1055,9 +1062,30 @@ struct iommufd_viommu *arm_vsmmu_alloc(struct device *dev,
>  				       struct iommu_domain *parent,
>  				       struct iommufd_ctx *ictx,
>  				       unsigned int viommu_type);
> +int arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state,
> +				    struct arm_smmu_nested_domain *nested_domain);
> +void arm_smmu_attach_commit_vmaster(struct arm_smmu_attach_state *state);
> +void arm_smmu_master_clear_vmaster(struct arm_smmu_master *master);
>  #else
>  #define arm_smmu_hw_info NULL
>  #define arm_vsmmu_alloc NULL
> +
> +static inline int
> +arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state,
> +				struct arm_smmu_nested_domain *nested_domain)
> +{
> +	return 0; /* NOP */
> +}

Please drop this comment.

> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
> index 5aa2e7af58b4..6b712b1ab429 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
> @@ -85,6 +85,51 @@ static void arm_smmu_make_nested_domain_ste(
>  	}
>  }
>  
> +int arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state,
> +				    struct arm_smmu_nested_domain *nested_domain)
> +{
> +	struct arm_smmu_vmaster *vmaster;
> +	unsigned long vsid;
> +	int ret;
> +
> +	iommu_group_mutex_assert(state->master->dev);
> +
> +	/* Skip invalid vSTE */
> +	if (!(nested_domain->ste[0] & cpu_to_le64(STRTAB_STE_0_V)))
> +		return 0;

Ok, and we don't need to set 'state->vmaster' in this case because we
only report stage-1 faults back to the vSMMU?

With the nits fixed:

Acked-by: Will Deacon <will@kernel.org>

Thanks,

Will