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[82.27.106.168]) by smtp.gmail.com with ESMTPSA id a1-20020aa7cf01000000b0042617ba6398sm7986163edy.34.2022.05.03.11.07.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 May 2022 11:07:52 -0700 (PDT) Date: Tue, 3 May 2022 19:07:27 +0100 From: Jean-Philippe Brucker To: Lu Baolu Subject: Re: [PATCH v5 03/12] iommu: Add attach/detach_dev_pasid domain ops Message-ID: References: <20220502014842.991097-1-baolu.lu@linux.intel.com> <20220502014842.991097-4-baolu.lu@linux.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220502014842.991097-4-baolu.lu@linux.intel.com> Cc: Kevin Tian , Dave Jiang , Ashok Raj , Robin Murphy , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Christoph Hellwig , Jean-Philippe Brucker , Vinod Koul , Jacob jun Pan , Jason Gunthorpe , Will Deacon X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Mon, May 02, 2022 at 09:48:33AM +0800, 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): > > - SVA (Shared Virtual Address) > - kernel DMA with PASID > - hardware-assist mediated device > > This adds a pair of common domain ops for this purpose and adds helpers > 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 Reviewed-by: Jean-Philippe Brucker just a nit below > --- > include/linux/iommu.h | 21 ++++++++++++ > drivers/iommu/iommu.c | 76 +++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 97 insertions(+) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index b8ffaf2cb1d0..ab36244d4e94 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -263,6 +263,8 @@ 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 > + * @attach_dev_pasid: attach an iommu domain to a pasid of device > + * @detach_dev_pasid: detach an iommu domain from a pasid of device > * @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. > @@ -283,6 +285,10 @@ 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 (*attach_dev_pasid)(struct iommu_domain *domain, > + struct device *dev, ioasid_t pasid); > + void (*detach_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); > @@ -678,6 +684,10 @@ 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 {}; > @@ -1051,6 +1061,17 @@ 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 29906bc16371..89c9d19ddb28 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -38,6 +38,7 @@ 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); > @@ -630,6 +631,7 @@ 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_simple_get(&iommu_group_ida, 0, 0, GFP_KERNEL); > if (ret < 0) { > @@ -3190,3 +3192,77 @@ bool iommu_group_dma_owner_claimed(struct iommu_group *group) > return user; > } > EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed); > + > +/* > + * Use standard PCI bus topology and isolation features to check immutable > + * singleton. Otherwise, assume the bus is static and then singleton can > + * know from the device count in the group. > + */ The comment doesn't really add anything that can't be directly understood from the code. > +static bool device_group_immutable_singleton(struct device *dev) > +{ > + struct iommu_group *group = iommu_group_get(dev); > + int count; > + > + if (!group) > + return false; > + > + mutex_lock(&group->mutex); > + count = iommu_group_device_count(group); > + mutex_unlock(&group->mutex); > + iommu_group_put(group); > + > + 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); > + > + return true; > +} > + > +int iommu_attach_device_pasid(struct iommu_domain *domain, > + struct device *dev, ioasid_t pasid) > +{ > + struct iommu_group *group; > + int ret = -EINVAL; > + void *curr; > + > + if (!domain->ops->attach_dev_pasid) > + return -EOPNOTSUPP; > + > + if (!device_group_immutable_singleton(dev)) > + return -EINVAL; > + > + group = iommu_group_get(dev); > + mutex_lock(&group->mutex); > + curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain, GFP_KERNEL); > + if (curr) > + goto out_unlock; > + ret = domain->ops->attach_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->detach_dev_pasid(domain, dev, pasid); > + xa_erase(&group->pasid_array, pasid); > + mutex_unlock(&group->mutex); > + > + iommu_group_put(group); > +} > -- > 2.25.1 > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu