An I/O address space takes effect in the iommu only after it's attached by a device. This patch provides iommufd_device_[de/at]tach_ioasid() helpers for this purpose. One device can be only attached to one ioasid at this point, but one ioasid can be attached by multiple devices.
The caller specifies the iommufd_device (returned at binding time) and the target ioasid when calling the helper function. Upon request, iommufd installs the specified I/O page table to the correct place in the IOMMU, according to the routing information (struct device* which represents RID) recorded in iommufd_device. Future variants could allow the caller to specify additional routing information (e.g. pasid/ssid) when multiple I/O address spaces are supported per device. Open: Per Jason's comment in below link, bus-specific wrappers are recommended. This RFC implements one wrapper for pci device. But it looks that struct pci_device is not used at all since iommufd_ device already carries all necessary info. So want to have another discussion on its necessity, e.g. whether making more sense to have bus-specific wrappers for binding, while leaving a common attaching helper per iommufd_device. https://lore.kernel.org/linux-iommu/20210528233649.gb3816...@nvidia.com/ TODO: When multiple devices are attached to a same ioasid, the permitted iova ranges and supported pgsize bitmap on this ioasid should be a common subset of all attached devices. iommufd needs to track such info per ioasid and update it every time when a new device is attached to the ioasid. This has not been done in this version yet, due to the temporary hack adopted in patch 16-18. The hack reuses vfio type1 driver which already includes the necessary logic for iova ranges and pgsize bitmap. Once we get a clear direction for those patches, that logic will be moved to this patch. Signed-off-by: Liu Yi L <yi.l....@intel.com> --- drivers/iommu/iommufd/iommufd.c | 226 ++++++++++++++++++++++++++++++++ include/linux/iommufd.h | 29 ++++ 2 files changed, 255 insertions(+) diff --git a/drivers/iommu/iommufd/iommufd.c b/drivers/iommu/iommufd/iommufd.c index e45d76359e34..25373a0e037a 100644 --- a/drivers/iommu/iommufd/iommufd.c +++ b/drivers/iommu/iommufd/iommufd.c @@ -51,6 +51,19 @@ struct iommufd_ioas { bool enforce_snoop; struct iommufd_ctx *ictx; refcount_t refs; + struct mutex lock; + struct list_head device_list; + struct iommu_domain *domain; +}; + +/* + * An ioas_device_info object is created per each successful attaching + * request. A list of objects are maintained per ioas when the address + * space is shared by multiple devices. + */ +struct ioas_device_info { + struct iommufd_device *idev; + struct list_head next; }; static int iommufd_fops_open(struct inode *inode, struct file *filep) @@ -119,6 +132,21 @@ static void iommufd_ctx_put(struct iommufd_ctx *ictx) kfree(ictx); } +static struct iommufd_ioas *ioasid_get_ioas(struct iommufd_ctx *ictx, int ioasid) +{ + struct iommufd_ioas *ioas; + + if (ioasid < 0) + return NULL; + + mutex_lock(&ictx->lock); + ioas = xa_load(&ictx->ioasid_xa, ioasid); + if (ioas) + refcount_inc(&ioas->refs); + mutex_unlock(&ictx->lock); + return ioas; +} + /* Caller should hold ictx->lock */ static void ioas_put_locked(struct iommufd_ioas *ioas) { @@ -128,11 +156,28 @@ static void ioas_put_locked(struct iommufd_ioas *ioas) if (!refcount_dec_and_test(&ioas->refs)) return; + WARN_ON(!list_empty(&ioas->device_list)); xa_erase(&ictx->ioasid_xa, ioasid); iommufd_ctx_put(ictx); kfree(ioas); } +/* + * Caller should hold a ictx reference when calling this function + * otherwise ictx might be freed in ioas_put_locked() then the last + * unlock becomes problematic. Alternatively we could have a fresh + * implementation of ioas_put instead of calling the locked function. + * In this case it can ensure ictx is freed after mutext_unlock(). + */ +static void ioas_put(struct iommufd_ioas *ioas) +{ + struct iommufd_ctx *ictx = ioas->ictx; + + mutex_lock(&ictx->lock); + ioas_put_locked(ioas); + mutex_unlock(&ictx->lock); +} + static int iommufd_ioasid_alloc(struct iommufd_ctx *ictx, unsigned long arg) { struct iommu_ioasid_alloc req; @@ -178,6 +223,9 @@ static int iommufd_ioasid_alloc(struct iommufd_ctx *ictx, unsigned long arg) iommufd_ctx_get(ictx); ioas->ictx = ictx; + mutex_init(&ioas->lock); + INIT_LIST_HEAD(&ioas->device_list); + refcount_set(&ioas->refs, 1); return ioasid; @@ -344,6 +392,166 @@ static struct miscdevice iommu_misc_dev = { .mode = 0666, }; +/* Caller should hold ioas->lock */ +static struct ioas_device_info *ioas_find_device(struct iommufd_ioas *ioas, + struct iommufd_device *idev) +{ + struct ioas_device_info *ioas_dev; + + list_for_each_entry(ioas_dev, &ioas->device_list, next) { + if (ioas_dev->idev == idev) + return ioas_dev; + } + + return NULL; +} + +static void ioas_free_domain_if_empty(struct iommufd_ioas *ioas) +{ + if (list_empty(&ioas->device_list)) { + iommu_domain_free(ioas->domain); + ioas->domain = NULL; + } +} + +static int ioas_check_device_compatibility(struct iommufd_ioas *ioas, + struct device *dev) +{ + bool snoop = false; + u32 addr_width; + int ret; + + /* + * currently we only support I/O page table with iommu enforce-snoop + * format. Attaching a device which doesn't support this format in its + * upstreaming iommu is rejected. + */ + ret = iommu_device_get_info(dev, IOMMU_DEV_INFO_FORCE_SNOOP, &snoop); + if (ret || !snoop) + return -EINVAL; + + ret = iommu_device_get_info(dev, IOMMU_DEV_INFO_ADDR_WIDTH, &addr_width); + if (ret || addr_width < ioas->addr_width) + return -EINVAL; + + /* TODO: also need to check permitted iova ranges and pgsize bitmap */ + + return 0; +} + +/** + * iommufd_device_attach_ioasid - attach device to an ioasid + * @idev: [in] Pointer to struct iommufd_device. + * @ioasid: [in] ioasid points to an I/O address space. + * + * Returns 0 for successful attach, otherwise returns error. + * + */ +int iommufd_device_attach_ioasid(struct iommufd_device *idev, int ioasid) +{ + struct iommufd_ioas *ioas; + struct ioas_device_info *ioas_dev; + struct iommu_domain *domain; + int ret; + + ioas = ioasid_get_ioas(idev->ictx, ioasid); + if (!ioas) { + pr_err_ratelimited("Trying to attach illegal or unkonwn IOASID %u\n", ioasid); + return -EINVAL; + } + + mutex_lock(&ioas->lock); + + /* Check for duplicates */ + if (ioas_find_device(ioas, idev)) { + ret = -EINVAL; + goto out_unlock; + } + + ret = ioas_check_device_compatibility(ioas, idev->dev); + if (ret) + goto out_unlock; + + ioas_dev = kzalloc(sizeof(*ioas_dev), GFP_KERNEL); + if (!ioas_dev) { + ret = -ENOMEM; + goto out_unlock; + } + + /* + * Each ioas is backed by an iommu domain, which is allocated + * when the ioas is attached for the first time and then shared + * by following devices. + */ + if (list_empty(&ioas->device_list)) { + struct iommu_domain *d; + + d = iommu_domain_alloc(idev->dev->bus); + if (!d) { + ret = -ENOMEM; + goto out_free; + } + ioas->domain = d; + } + domain = ioas->domain; + + /* Install the I/O page table to the iommu for this device */ + ret = iommu_attach_device(domain, idev->dev); + if (ret) + goto out_domain; + + ioas_dev->idev = idev; + list_add(&ioas_dev->next, &ioas->device_list); + mutex_unlock(&ioas->lock); + + return 0; +out_domain: + ioas_free_domain_if_empty(ioas); +out_free: + kfree(ioas_dev); +out_unlock: + mutex_unlock(&ioas->lock); + ioas_put(ioas); + + return ret; +} +EXPORT_SYMBOL_GPL(iommufd_device_attach_ioasid); + +/** + * iommufd_device_detach_ioasid - Detach an ioasid from a device. + * @idev: [in] Pointer to struct iommufd_device. + * @ioasid: [in] ioasid points to an I/O address space. + * + */ +void iommufd_device_detach_ioasid(struct iommufd_device *idev, int ioasid) +{ + struct iommufd_ioas *ioas; + struct ioas_device_info *ioas_dev; + + ioas = ioasid_get_ioas(idev->ictx, ioasid); + if (!ioas) + return; + + mutex_lock(&ioas->lock); + ioas_dev = ioas_find_device(ioas, idev); + if (!ioas_dev) { + mutex_unlock(&ioas->lock); + goto out; + } + + list_del(&ioas_dev->next); + iommu_detach_device(ioas->domain, idev->dev); + ioas_free_domain_if_empty(ioas); + kfree(ioas_dev); + mutex_unlock(&ioas->lock); + + /* release the reference acquired at the start of this function */ + ioas_put(ioas); +out: + ioas_put(ioas); +} +EXPORT_SYMBOL_GPL(iommufd_device_detach_ioasid); + /** * iommufd_bind_device - Bind a physical device marked by a device * cookie to an iommu fd. @@ -426,8 +634,26 @@ EXPORT_SYMBOL_GPL(iommufd_bind_device); void iommufd_unbind_device(struct iommufd_device *idev) { struct iommufd_ctx *ictx = idev->ictx; + struct iommufd_ioas *ioas; + unsigned long index; mutex_lock(&ictx->lock); + xa_for_each(&ictx->ioasid_xa, index, ioas) { + struct ioas_device_info *ioas_dev; + + mutex_lock(&ioas->lock); + ioas_dev = ioas_find_device(ioas, idev); + if (!ioas_dev) { + mutex_unlock(&ioas->lock); + continue; + } + list_del(&ioas_dev->next); + iommu_detach_device(ioas->domain, idev->dev); + ioas_free_domain_if_empty(ioas); + kfree(ioas_dev); + mutex_unlock(&ioas->lock); + ioas_put_locked(ioas); + } xa_erase(&ictx->device_xa, idev->id); mutex_unlock(&ictx->lock); /* Exit the security context */ diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h index 1dd6515e7816..01a4fe934143 100644 --- a/include/linux/iommufd.h +++ b/include/linux/iommufd.h @@ -13,6 +13,7 @@ #include <linux/errno.h> #include <linux/err.h> #include <linux/device.h> +#include <linux/pci.h> #define IOMMUFD_IOASID_MAX ((unsigned int)(0x7FFFFFFF)) #define IOMMUFD_IOASID_MIN 0 @@ -27,6 +28,16 @@ struct iommufd_device * iommufd_bind_device(int fd, struct device *dev, u64 dev_cookie); void iommufd_unbind_device(struct iommufd_device *idev); +int iommufd_device_attach_ioasid(struct iommufd_device *idev, int ioasid); +void iommufd_device_detach_ioasid(struct iommufd_device *idev, int ioasid); + +static inline int +__pci_iommufd_device_attach_ioasid(struct pci_dev *pdev, + struct iommufd_device *idev, int ioasid) +{ + return iommufd_device_attach_ioasid(idev, ioasid); +} + #else /* !CONFIG_IOMMUFD */ static inline struct iommufd_device * iommufd_bind_device(int fd, struct device *dev, u64 dev_cookie) @@ -37,5 +48,23 @@ iommufd_bind_device(int fd, struct device *dev, u64 dev_cookie) static inline void iommufd_unbind_device(struct iommufd_device *idev) { } + +static inline int iommufd_device_attach_ioasid(struct iommufd_device *idev, + int ioasid) +{ + return -ENODEV; +} + +static inline void iommufd_device_detach_ioasid(struct iommufd_device *idev, + int ioasid) +{ +} + +static inline int +__pci_iommufd_device_attach_ioasid(struct pci_dev *pdev, + struct iommufd_device *idev, int ioasid) +{ + return -ENODEV; +} #endif /* CONFIG_IOMMUFD */ #endif /* __LINUX_IOMMUFD_H */ -- 2.25.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
