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SubjectRe: [PATCH v2 1/1] vfio/type1: Add vfio_group_domain()
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Hi Alex,

Thanks a lot for your review comments.

On 12/1/20 4:57 AM, Alex Williamson wrote:
> On Thu, 26 Nov 2020 09:27:26 +0800
> Lu Baolu <baolu.lu@linux.intel.com> wrote:
>
>> Add the API for getting the domain from a vfio group. This could be used
>> by the physical device drivers which rely on the vfio/mdev framework for
>> mediated device user level access. The typical use case like below:
>>
>> unsigned int pasid;
>> struct vfio_group *vfio_group;
>> struct iommu_domain *iommu_domain;
>> struct device *dev = mdev_dev(mdev);
>> struct device *iommu_device = mdev_get_iommu_device(dev);
>>
>> if (!iommu_device ||
>> !iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX))
>> return -EINVAL;
>>
>> vfio_group = vfio_group_get_external_user_from_dev(dev);(dev);
>> if (IS_ERR_OR_NULL(vfio_group))
>> return -EFAULT;
>>
>> iommu_domain = vfio_group_domain(vfio_group);
>> if (IS_ERR_OR_NULL(iommu_domain)) {
>> vfio_group_put_external_user(vfio_group);
>> return -EFAULT;
>> }
>>
>> pasid = iommu_aux_get_pasid(iommu_domain, iommu_device);
>> if (pasid < 0) {
>> vfio_group_put_external_user(vfio_group);
>> return -EFAULT;
>> }
>>
>> /* Program device context with pasid value. */
>> ...
>>
>> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
>> ---
>> drivers/vfio/vfio.c | 18 ++++++++++++++++++
>> drivers/vfio/vfio_iommu_type1.c | 23 +++++++++++++++++++++++
>> include/linux/vfio.h | 3 +++
>> 3 files changed, 44 insertions(+)
>>
>> Change log:
>> - v1: https://lore.kernel.org/linux-iommu/20201112022407.2063896-1-baolu.lu@linux.intel.com/
>> - Changed according to comments @ https://lore.kernel.org/linux-iommu/20201116125631.2d043fcd@w520.home/
>>
>> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
>> index 2151bc7f87ab..62c652111c88 100644
>> --- a/drivers/vfio/vfio.c
>> +++ b/drivers/vfio/vfio.c
>> @@ -2331,6 +2331,24 @@ int vfio_unregister_notifier(struct device *dev, enum vfio_notify_type type,
>> }
>> EXPORT_SYMBOL(vfio_unregister_notifier);
>>
>> +struct iommu_domain *vfio_group_domain(struct vfio_group *group)
>> +{
>> + struct vfio_container *container;
>> + struct vfio_iommu_driver *driver;
>> +
>> + if (!group)
>> + return ERR_PTR(-EINVAL);
>> +
>> + container = group->container;
>> + driver = container->iommu_driver;
>> + if (likely(driver && driver->ops->group_domain))
>> + return driver->ops->group_domain(container->iommu_data,
>> + group->iommu_group);
>> + else
>> + return ERR_PTR(-ENOTTY);
>> +}
>> +EXPORT_SYMBOL(vfio_group_domain);
>
>
> _GPL? I don't see that there's a way for a driver to get the
> vfio_group pointer that's not already _GPL.
>

It should be _GPL. Will fix it.

>
>> +
>> /**
>> * Module/class support
>> */
>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>> index 67e827638995..783f18f21b95 100644
>> --- a/drivers/vfio/vfio_iommu_type1.c
>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> @@ -2980,6 +2980,28 @@ static int vfio_iommu_type1_dma_rw(void *iommu_data, dma_addr_t user_iova,
>> return ret;
>> }
>>
>> +static void *vfio_iommu_type1_group_domain(void *iommu_data,
>> + struct iommu_group *iommu_group)
>> +{
>> + struct vfio_iommu *iommu = iommu_data;
>> + struct iommu_domain *domain = NULL;
>> + struct vfio_domain *d;
>> +
>> + if (!iommu || !iommu_group)
>> + return ERR_PTR(-EINVAL);
>> +
>> + mutex_lock(&iommu->lock);
>> + list_for_each_entry(d, &iommu->domain_list, next) {
>> + if (find_iommu_group(d, iommu_group)) {
>> + domain = d->domain;
>> + break;
>> + }
>> + }
>> + mutex_unlock(&iommu->lock);
>> +
>> + return domain;
>> +}
>
>
> Why does this return void* rather than struct iommu_domain*, and why
> does the error case return an ERR_PTR but the not-found case returns
> NULL?

I will change it to return iommu_domain* and return an error number for
the not-found case.

Best regards,
baolu

> Thanks,
>
> Alex
>
>
>> +
>> static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
>> .name = "vfio-iommu-type1",
>> .owner = THIS_MODULE,
>> @@ -2993,6 +3015,7 @@ static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
>> .register_notifier = vfio_iommu_type1_register_notifier,
>> .unregister_notifier = vfio_iommu_type1_unregister_notifier,
>> .dma_rw = vfio_iommu_type1_dma_rw,
>> + .group_domain = vfio_iommu_type1_group_domain,
>> };
>>
>> static int __init vfio_iommu_type1_init(void)
>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
>> index 38d3c6a8dc7e..a0613a6f21cc 100644
>> --- a/include/linux/vfio.h
>> +++ b/include/linux/vfio.h
>> @@ -90,6 +90,7 @@ struct vfio_iommu_driver_ops {
>> struct notifier_block *nb);
>> int (*dma_rw)(void *iommu_data, dma_addr_t user_iova,
>> void *data, size_t count, bool write);
>> + void *(*group_domain)(void *iommu_data, struct iommu_group *group);
>> };
>>
>> extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops);
>> @@ -126,6 +127,8 @@ extern int vfio_group_unpin_pages(struct vfio_group *group,
>> extern int vfio_dma_rw(struct vfio_group *group, dma_addr_t user_iova,
>> void *data, size_t len, bool write);
>>
>> +extern struct iommu_domain *vfio_group_domain(struct vfio_group *group);
>> +
>> /* each type has independent events */
>> enum vfio_notify_type {
>> VFIO_IOMMU_NOTIFY = 0,
>

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