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Message-ID: <20201116125631.2d043fcd@w520.home>
Date: Mon, 16 Nov 2020 12:56:31 -0700
From: Alex Williamson <alex.williamson@...hat.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: Cornelia Huck <cohuck@...hat.com>, Joerg Roedel <joro@...tes.org>,
Robin Murphy <robin.murphy@....com>,
Jean-Philippe Brucker <jean-philippe@...aro.org>,
Kevin Tian <kevin.tian@...el.com>,
Ashok Raj <ashok.raj@...el.com>,
Dave Jiang <dave.jiang@...el.com>,
Liu Yi L <yi.l.liu@...el.com>, Zeng Xin <xin.zeng@...el.com>,
iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org
Subject: Re: [PATCH 1/1] vfio/type1: Add subdev_ioasid callback to
vfio_iommu_driver_ops
On Thu, 12 Nov 2020 10:24:07 +0800
Lu Baolu <baolu.lu@...ux.intel.com> wrote:
> Add API for getting the ioasid of a subdevice (vfio/mdev). This calls
> into the backend IOMMU module to get the actual value or error number
> if ioasid for subdevice is not supported. The physical device driver
> implementations which rely on the vfio/mdev framework for mediated
> device user level access could typically consume this interface like
> below:
>
> struct device *dev = mdev_dev(mdev);
> unsigned int pasid;
> int ret;
>
> ret = vfio_subdev_ioasid(dev, &pasid);
> if (ret < 0)
> return ret;
>
> /* Program device context with pasid value. */
> ....
Seems like an overly specific callback. We already export means for
you to get a vfio_group, test that a device is an mdev, and get the
iommu device from an mdev. So you can already test whether a given
device is an mdev with an iommu backing device that supports aux
domains. The only missing piece seems to be that you can't get the
domain for a group in order to retrieve the pasid. So why aren't we
exporting a callback that given a vfio_group provides the iommu domain?
Thanks,
Alex
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
> drivers/vfio/vfio.c | 34 ++++++++++++++++++++
> drivers/vfio/vfio_iommu_type1.c | 57 +++++++++++++++++++++++++++++++++
> include/linux/vfio.h | 4 +++
> 3 files changed, 95 insertions(+)
>
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 2151bc7f87ab..4931e1492921 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -2331,6 +2331,40 @@ int vfio_unregister_notifier(struct device *dev, enum vfio_notify_type type,
> }
> EXPORT_SYMBOL(vfio_unregister_notifier);
>
> +int vfio_subdev_ioasid(struct device *dev, unsigned int *id)
> +{
> + struct vfio_container *container;
> + struct vfio_iommu_driver *driver;
> + struct vfio_group *group;
> + int ret;
> +
> + if (!dev || !id)
> + return -EINVAL;
> +
> + group = vfio_group_get_from_dev(dev);
> + if (!group)
> + return -ENODEV;
> +
> + ret = vfio_group_add_container_user(group);
> + if (ret)
> + goto out;
> +
> + container = group->container;
> + driver = container->iommu_driver;
> + if (likely(driver && driver->ops->subdev_ioasid))
> + ret = driver->ops->subdev_ioasid(container->iommu_data,
> + group->iommu_group, id);
> + else
> + ret = -ENOTTY;
> +
> + vfio_group_try_dissolve_container(group);
> +
> +out:
> + vfio_group_put(group);
> + return ret;
> +}
> +EXPORT_SYMBOL(vfio_subdev_ioasid);
> +
> /**
> * Module/class support
> */
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 67e827638995..f94cc7707d7e 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -2980,6 +2980,62 @@ static int vfio_iommu_type1_dma_rw(void *iommu_data, dma_addr_t user_iova,
> return ret;
> }
>
> +static int vfio_iommu_type1_subdev_ioasid(void *iommu_data,
> + struct iommu_group *iommu_group,
> + unsigned int *id)
> +{
> + struct vfio_iommu *iommu = iommu_data;
> + struct vfio_domain *domain = NULL, *d;
> + struct device *iommu_device = NULL;
> + struct bus_type *bus = NULL;
> + int ret;
> +
> + if (!iommu || !iommu_group || !id)
> + return -EINVAL;
> +
> + mutex_lock(&iommu->lock);
> + ret = iommu_group_for_each_dev(iommu_group, &bus, vfio_bus_type);
> + if (ret)
> + goto out;
> +
> + if (!vfio_bus_is_mdev(bus)) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + ret = iommu_group_for_each_dev(iommu_group, &iommu_device,
> + vfio_mdev_iommu_device);
> + if (ret || !iommu_device ||
> + !iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX)) {
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + list_for_each_entry(d, &iommu->domain_list, next) {
> + if (find_iommu_group(d, iommu_group)) {
> + domain = d;
> + break;
> + }
> + }
> +
> + if (!domain) {
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + ret = iommu_aux_get_pasid(domain->domain, iommu_device);
> + if (ret > 0) {
> + *id = ret;
> + ret = 0;
> + } else {
> + ret = -ENOSPC;
> + }
> +
> +out:
> + mutex_unlock(&iommu->lock);
> + return ret;
> +}
> +
> static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
> .name = "vfio-iommu-type1",
> .owner = THIS_MODULE,
> @@ -2993,6 +3049,7 @@ 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,
> + .subdev_ioasid = vfio_iommu_type1_subdev_ioasid,
> };
>
> static int __init vfio_iommu_type1_init(void)
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 38d3c6a8dc7e..6dcf09a2796d 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -90,6 +90,9 @@ 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);
> + int (*subdev_ioasid)(void *iommu_data,
> + struct iommu_group *group,
> + unsigned int *id);
> };
>
> extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops);
> @@ -125,6 +128,7 @@ 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 int vfio_subdev_ioasid(struct device *dev, unsigned int *id);
>
> /* each type has independent events */
> enum vfio_notify_type {
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