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Date: Sun, 31 Jul 2022 20:10:06 +0800
From: Yi Liu <yi.l.liu@...el.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>,
Joerg Roedel <joro@...tes.org>,
Jason Gunthorpe <jgg@...dia.com>,
Christoph Hellwig <hch@...radead.org>,
Kevin Tian <kevin.tian@...el.com>,
Ashok Raj <ashok.raj@...el.com>,
"Will Deacon" <will@...nel.org>,
Robin Murphy <robin.murphy@....com>,
"Jean-Philippe Brucker" <jean-philippe@...aro.com>,
Dave Jiang <dave.jiang@...el.com>,
"Vinod Koul" <vkoul@...nel.org>
CC: Eric Auger <eric.auger@...hat.com>,
Jacob jun Pan <jacob.jun.pan@...el.com>,
Zhangfei Gao <zhangfei.gao@...aro.org>,
Zhu Tony <tony.zhu@...el.com>, <iommu@...ts.linux.dev>,
<linux-kernel@...r.kernel.org>,
Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: Re: [PATCH v10 04/12] iommu: Add attach/detach_dev_pasid iommu
interface
On 2022/7/5 13:07, Lu Baolu wrote:
> Attaching an IOMMU domain to a PASID of a device is a generic operation
> for modern IOMMU drivers which support PASID-granular DMA address
> translation. Currently visible usage scenarios include (but not limited):
s/visible/known/? "known" seems better. up to you. :-)
>
> - SVA (Shared Virtual Address)
> - kernel DMA with PASID
> - hardware-assist mediated device
>
> This adds a pair of domain ops for this purpose and adds the interfaces
> for device drivers to attach/detach a domain to/from a {device, PASID}.
> Some buses, like PCI, route packets without considering the PASID value.
> Thus a DMA target address with PASID might be treated as P2P if the
> address falls into the MMIO BAR of other devices in the group. To make
> things simple, these interfaces only apply to devices belonging to the
> singleton groups, and the singleton is immutable in fabric (i.e. not
> affected by hotplug).
>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> Reviewed-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
> Tested-by: Zhangfei Gao <zhangfei.gao@...aro.org>
> Tested-by: Tony Zhu <tony.zhu@...el.com>
> ---
> include/linux/iommu.h | 21 ++++++++++++
> drivers/iommu/iommu.c | 75 +++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 96 insertions(+)
Reviewed-by: Yi Liu <yi.l.liu@...el.com>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index f41eb2b3c7da..f2b5aa7efe43 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -262,6 +262,8 @@ struct iommu_ops {
> * struct iommu_domain_ops - domain specific operations
> * @attach_dev: attach an iommu domain to a device
> * @detach_dev: detach an iommu domain from a device
> + * @set_dev_pasid: set an iommu domain to a pasid of device
> + * @block_dev_pasid: block pasid of device from using iommu domain
> * @map: map a physically contiguous memory region to an iommu domain
> * @map_pages: map a physically contiguous set of pages of the same size to
> * an iommu domain.
> @@ -282,6 +284,10 @@ struct iommu_ops {
> struct iommu_domain_ops {
> int (*attach_dev)(struct iommu_domain *domain, struct device *dev);
> void (*detach_dev)(struct iommu_domain *domain, struct device *dev);
> + int (*set_dev_pasid)(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid);
> + void (*block_dev_pasid)(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid);
>
> int (*map)(struct iommu_domain *domain, unsigned long iova,
> phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
> @@ -679,6 +685,10 @@ int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner);
> void iommu_group_release_dma_owner(struct iommu_group *group);
> bool iommu_group_dma_owner_claimed(struct iommu_group *group);
>
> +int iommu_attach_device_pasid(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid);
> +void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid);
> #else /* CONFIG_IOMMU_API */
>
> struct iommu_ops {};
> @@ -1052,6 +1062,17 @@ static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group)
> {
> return false;
> }
> +
> +static inline int iommu_attach_device_pasid(struct iommu_domain *domain,
> + struct device *dev, ioasid_t pasid)
> +{
> + return -ENODEV;
> +}
> +
> +static inline void iommu_detach_device_pasid(struct iommu_domain *domain,
> + struct device *dev, ioasid_t pasid)
> +{
> +}
> #endif /* CONFIG_IOMMU_API */
>
> /**
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 74a0a3ec0907..be48b09371f4 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -39,6 +39,7 @@ struct iommu_group {
> struct kobject kobj;
> struct kobject *devices_kobj;
> struct list_head devices;
> + struct xarray pasid_array;
> struct mutex mutex;
> void *iommu_data;
> void (*iommu_data_release)(void *iommu_data);
> @@ -660,6 +661,7 @@ struct iommu_group *iommu_group_alloc(void)
> mutex_init(&group->mutex);
> INIT_LIST_HEAD(&group->devices);
> INIT_LIST_HEAD(&group->entry);
> + xa_init(&group->pasid_array);
>
> ret = ida_alloc(&iommu_group_ida, GFP_KERNEL);
> if (ret < 0) {
> @@ -3271,3 +3273,76 @@ bool iommu_group_dma_owner_claimed(struct iommu_group *group)
> return user;
> }
> EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed);
> +
> +static bool iommu_group_immutable_singleton(struct iommu_group *group,
> + struct device *dev)
> +{
> + int count;
> +
> + mutex_lock(&group->mutex);
> + count = iommu_group_device_count(group);
> + mutex_unlock(&group->mutex);
> +
> + if (count != 1)
> + return false;
> +
> + /*
> + * The PCI device could be considered to be fully isolated if all
> + * devices on the path from the device to the host-PCI bridge are
> + * protected from peer-to-peer DMA by ACS.
> + */
> + if (dev_is_pci(dev))
> + return pci_acs_path_enabled(to_pci_dev(dev), NULL,
> + REQ_ACS_FLAGS);
> +
> + /*
> + * Otherwise, the device came from DT/ACPI, assume it is static and
> + * then singleton can know from the device count in the group.
> + */
> + return true;
> +}
> +
> +int iommu_attach_device_pasid(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid)
> +{
> + struct iommu_group *group;
> + void *curr;
> + int ret;
> +
> + if (!domain->ops->set_dev_pasid)
> + return -EOPNOTSUPP;
> +
> + group = iommu_group_get(dev);
> + if (!group || !iommu_group_immutable_singleton(group, dev)) {
> + iommu_group_put(group);
> + return -EINVAL;
> + }
> +
> + mutex_lock(&group->mutex);
> + curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain, GFP_KERNEL);
> + if (curr) {
> + ret = xa_err(curr) ? : -EBUSY;
> + goto out_unlock;
> + }
> + ret = domain->ops->set_dev_pasid(domain, dev, pasid);
> + if (ret)
> + xa_erase(&group->pasid_array, pasid);
> +out_unlock:
> + mutex_unlock(&group->mutex);
> + iommu_group_put(group);
> +
> + return ret;
> +}
> +
> +void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid)
> +{
> + struct iommu_group *group = iommu_group_get(dev);
> +
> + mutex_lock(&group->mutex);
> + domain->ops->block_dev_pasid(domain, dev, pasid);
> + xa_erase(&group->pasid_array, pasid);
> + mutex_unlock(&group->mutex);
> +
> + iommu_group_put(group);
> +}
--
Regards,
Yi Liu
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