Re: [PATCH v9 4/7] iommu/arm-smmu: Add a pointer to the attached device to smmu_domain

Will Deacon
2020-07-13T15:10:36Z

On Fri, Jun 26, 2020 at 02:00:38PM -0600, Jordan Crouse wrote:
> Add a link to the pointer to the struct device that is attached to a
> domain. This makes it easy to get the pointer if it is needed in the
> implementation specific code.
>
> Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
> ---
>
> drivers/iommu/arm-smmu.c | 6 ++++--
> drivers/iommu/arm-smmu.h | 1 +
> 2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 048de2681670..060139452c54 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -668,7 +668,8 @@ static void arm_smmu_write_context_bank(struct arm_smmu_device *smmu, int idx)
> }
>
> static int arm_smmu_init_domain_context(struct iommu_domain *domain,
> - struct arm_smmu_device *smmu)
> + struct arm_smmu_device *smmu,
> + struct device *dev)
> {
> int irq, start, ret = 0;
> unsigned long ias, oas;
> @@ -801,6 +802,7 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
> cfg->asid = cfg->cbndx;
>
> smmu_domain->smmu = smmu;
> + smmu_domain->dev = dev;
>
> pgtbl_cfg = (struct io_pgtable_cfg) {
> .pgsize_bitmap = smmu->pgsize_bitmap,
> @@ -1190,7 +1192,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
> return ret;
>
> /* Ensure that the domain is finalised */
> - ret = arm_smmu_init_domain_context(domain, smmu);
> + ret = arm_smmu_init_domain_context(domain, smmu, dev);
> if (ret < 0)
> goto rpm_put;
>
> diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h
> index 5f2de20e883b..d33cfe26b2f5 100644
> --- a/drivers/iommu/arm-smmu.h
> +++ b/drivers/iommu/arm-smmu.h
> @@ -345,6 +345,7 @@ struct arm_smmu_domain {
> struct mutex init_mutex; /* Protects smmu pointer */
> spinlock_t cb_lock; /* Serialises ATS1* ops and TLB syncs */
> struct iommu_domain domain;
> + struct device *dev; /* Device attached to this domain */

This really doesn't feel right to me -- you can generally have multiple
devices attached to a domain and they can come and go without the domain
being destroyed. Perhaps you could instead identify the GPU during
cfg_probe() and squirrel that information away somewhere?

The rest of the series looks ok to me.

Will