diff options
Diffstat (limited to 'drivers/iommu/iommu-sva.c')
| -rw-r--r-- | drivers/iommu/iommu-sva.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c new file mode 100644 index 0000000000..b78671a8a9 --- /dev/null +++ b/drivers/iommu/iommu-sva.c @@ -0,0 +1,212 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Helpers for IOMMU drivers implementing SVA + */ +#include <linux/mmu_context.h> +#include <linux/mutex.h> +#include <linux/sched/mm.h> +#include <linux/iommu.h> + +#include "iommu-sva.h" + +static DEFINE_MUTEX(iommu_sva_lock); + +/* Allocate a PASID for the mm within range (inclusive) */ +static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev) +{ + ioasid_t pasid; + int ret = 0; + + if (!arch_pgtable_dma_compat(mm)) + return -EBUSY; + + mutex_lock(&iommu_sva_lock); + /* Is a PASID already associated with this mm? */ + if (mm_valid_pasid(mm)) { + if (mm->pasid >= dev->iommu->max_pasids) + ret = -EOVERFLOW; + goto out; + } + + pasid = iommu_alloc_global_pasid(dev); + if (pasid == IOMMU_PASID_INVALID) { + ret = -ENOSPC; + goto out; + } + mm->pasid = pasid; + ret = 0; +out: + mutex_unlock(&iommu_sva_lock); + return ret; +} + +/** + * iommu_sva_bind_device() - Bind a process address space to a device + * @dev: the device + * @mm: the mm to bind, caller must hold a reference to mm_users + * + * Create a bond between device and address space, allowing the device to + * access the mm using the PASID returned by iommu_sva_get_pasid(). If a + * bond already exists between @device and @mm, an additional internal + * reference is taken. Caller must call iommu_sva_unbind_device() + * to release each reference. + * + * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called first, to + * initialize the required SVA features. + * + * On error, returns an ERR_PTR value. + */ +struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm) +{ + struct iommu_domain *domain; + struct iommu_sva *handle; + int ret; + + /* Allocate mm->pasid if necessary. */ + ret = iommu_sva_alloc_pasid(mm, dev); + if (ret) + return ERR_PTR(ret); + + handle = kzalloc(sizeof(*handle), GFP_KERNEL); + if (!handle) + return ERR_PTR(-ENOMEM); + + mutex_lock(&iommu_sva_lock); + /* Search for an existing domain. */ + domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid, + IOMMU_DOMAIN_SVA); + if (IS_ERR(domain)) { + ret = PTR_ERR(domain); + goto out_unlock; + } + + if (domain) { + domain->users++; + goto out; + } + + /* Allocate a new domain and set it on device pasid. */ + domain = iommu_sva_domain_alloc(dev, mm); + if (!domain) { + ret = -ENOMEM; + goto out_unlock; + } + + ret = iommu_attach_device_pasid(domain, dev, mm->pasid); + if (ret) + goto out_free_domain; + domain->users = 1; +out: + mutex_unlock(&iommu_sva_lock); + handle->dev = dev; + handle->domain = domain; + + return handle; + +out_free_domain: + iommu_domain_free(domain); +out_unlock: + mutex_unlock(&iommu_sva_lock); + kfree(handle); + + return ERR_PTR(ret); +} +EXPORT_SYMBOL_GPL(iommu_sva_bind_device); + +/** + * iommu_sva_unbind_device() - Remove a bond created with iommu_sva_bind_device + * @handle: the handle returned by iommu_sva_bind_device() + * + * Put reference to a bond between device and address space. The device should + * not be issuing any more transaction for this PASID. All outstanding page + * requests for this PASID must have been flushed to the IOMMU. + */ +void iommu_sva_unbind_device(struct iommu_sva *handle) +{ + struct iommu_domain *domain = handle->domain; + ioasid_t pasid = domain->mm->pasid; + struct device *dev = handle->dev; + + mutex_lock(&iommu_sva_lock); + if (--domain->users == 0) { + iommu_detach_device_pasid(domain, dev, pasid); + iommu_domain_free(domain); + } + mutex_unlock(&iommu_sva_lock); + kfree(handle); +} +EXPORT_SYMBOL_GPL(iommu_sva_unbind_device); + +u32 iommu_sva_get_pasid(struct iommu_sva *handle) +{ + struct iommu_domain *domain = handle->domain; + + return domain->mm->pasid; +} +EXPORT_SYMBOL_GPL(iommu_sva_get_pasid); + +/* + * I/O page fault handler for SVA + */ +enum iommu_page_response_code +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data) +{ + vm_fault_t ret; + struct vm_area_struct *vma; + struct mm_struct *mm = data; + unsigned int access_flags = 0; + unsigned int fault_flags = FAULT_FLAG_REMOTE; + struct iommu_fault_page_request *prm = &fault->prm; + enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID; + + if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID)) + return status; + + if (!mmget_not_zero(mm)) + return status; + + mmap_read_lock(mm); + + vma = vma_lookup(mm, prm->addr); + if (!vma) + /* Unmapped area */ + goto out_put_mm; + + if (prm->perm & IOMMU_FAULT_PERM_READ) + access_flags |= VM_READ; + + if (prm->perm & IOMMU_FAULT_PERM_WRITE) { + access_flags |= VM_WRITE; + fault_flags |= FAULT_FLAG_WRITE; + } + + if (prm->perm & IOMMU_FAULT_PERM_EXEC) { + access_flags |= VM_EXEC; + fault_flags |= FAULT_FLAG_INSTRUCTION; + } + + if (!(prm->perm & IOMMU_FAULT_PERM_PRIV)) + fault_flags |= FAULT_FLAG_USER; + + if (access_flags & ~vma->vm_flags) + /* Access fault */ + goto out_put_mm; + + ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL); + status = ret & VM_FAULT_ERROR ? IOMMU_PAGE_RESP_INVALID : + IOMMU_PAGE_RESP_SUCCESS; + +out_put_mm: + mmap_read_unlock(mm); + mmput(mm); + + return status; +} + +void mm_pasid_drop(struct mm_struct *mm) +{ + if (likely(!mm_valid_pasid(mm))) + return; + + iommu_free_global_pasid(mm->pasid); +} |