Re: [PATCH v10 08/12] iommu/sva: Refactoring iommu_sva_bind/unbind_device()

From: Jean-Philippe Brucker
Date: Mon Jul 25 2022 - 05:53:13 EST


On Mon, Jul 25, 2022 at 05:33:05PM +0800, Baolu Lu wrote:
> Hi Jean,
>
> On 2022/7/25 15:39, Jean-Philippe Brucker wrote:
> > On Sun, Jul 24, 2022 at 09:48:15PM +0800, Baolu Lu wrote:
> > > /*
> > > * iommu_detach_device_pasid() - Detach the domain from pasid of device
> > > * @domain: the iommu domain.
> > > * @dev: the attached device.
> > > * @pasid: the pasid of the device.
> > > *
> > > * The @domain must have been attached to @pasid of the @dev with
> > > * iommu_detach_device_pasid().
> > > */
> > > void iommu_detach_device_pasid(struct iommu_domain *domain, struct device
> > > *dev,
> > > ioasid_t pasid)
> > > {
> > > struct iommu_group *group = iommu_group_get(dev);
> > > struct group_pasid *param;
> > >
> > > mutex_lock(&group->mutex);
> > > domain->ops->set_dev_pasid(group->blocking_domain, dev, pasid);
> > Please also pass the old domain to this detach() function, so that the
> > IOMMU driver doesn't have to keep track of them internally.
>
> The iommu core provides the interface to retrieve attached domain with a
> {device, pasid} pair. Therefore in the smmuv3 driver, the set_dev_pasid
> could do like this:

Thanks for the example, yes I can do something like this. I maintain that
attach+detach is clearer, but as long as it can be made to work, fine by
me

Thanks,
Jean

>
> +static int arm_smmu_sva_set_dev_pasid(struct iommu_domain *domain,
> + struct device *dev, ioasid_t id)
> +{
> + int ret = 0;
> + struct mm_struct *mm;
> + struct iommu_sva *handle;
> +
> + /*
> + * Detach the domain if a blocking domain is set. Check the
> + * right domain type once the IOMMU driver supports a real
> + * blocking domain.
> + */
> + if (!domain || domain->type == IOMMU_DOMAIN_UNMANAGED) {
> + struct pasid_iommu *param;
> +
> + param = iommu_device_pasid_param(dev, id);
> + if (!param || !param->domain)
> + return -EINVAL;
> + arm_smmu_sva_block_dev_pasid(param->domain, dev, id);
> +
> + return 0;
> + }
> +
> + mm = domain->mm;
> + mutex_lock(&sva_lock);
> + handle = __arm_smmu_sva_bind(dev, mm);
> + if (IS_ERR(handle))
> + ret = PTR_ERR(handle);
> + mutex_unlock(&sva_lock);
> +
> + return ret;
> +}
>
> The check of "(!domain || domain->type == IOMMU_DOMAIN_UNMANAGED)" looks
> odd, but could get cleaned up after a real blocking domain is added.
> Then, we can simply check "domain->type == IOMMU_DOMAIN_BLOCKING".