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* Copyright © 2015 Intel Corporation.
* Authors: David Woodhouse <>
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
#ifndef __INTEL_SVM_H__
#define __INTEL_SVM_H__
struct device;
struct svm_dev_ops {
void (*fault_cb)(struct device *dev, int pasid, u64 address,
void *private, int rwxp, int response);
/* Values for rxwp in fault_cb callback */
#define SVM_REQ_READ (1<<3)
#define SVM_REQ_WRITE (1<<2)
#define SVM_REQ_EXEC (1<<1)
#define SVM_REQ_PRIV (1<<0)
* The SVM_FLAG_PRIVATE_PASID flag requests a PASID which is *not* the "main"
* PASID for the current process. Even if a PASID already exists, a new one
* will be allocated. And the PASID allocated with SVM_FLAG_PRIVATE_PASID
* will not be given to subsequent callers. This facility allows a driver to
* disambiguate between multiple device contexts which access the same MM,
* if there is no other way to do so. It should be used sparingly, if at all.
* The SVM_FLAG_SUPERVISOR_MODE flag requests a PASID which can be used only
* for access to kernel addresses. No IOTLB flushes are automatically done
* for kernel mappings; it is valid only for access to the kernel's static
* 1:1 mapping of physical memory — not to vmalloc or even module mappings.
* A future API addition may permit the use of such ranges, by means of an
* explicit IOTLB flush call (akin to the DMA API's unmap method).
* It is unlikely that we will ever hook into flush_tlb_kernel_range() to
* do such IOTLB flushes automatically.
* intel_svm_bind_mm() - Bind the current process to a PASID
* @dev: Device to be granted acccess
* @pasid: Address for allocated PASID
* @flags: Flags. Later for requesting supervisor mode, etc.
* @ops: Callbacks to device driver
* This function attempts to enable PASID support for the given device.
* If the @pasid argument is non-%NULL, a PASID is allocated for access
* to the MM of the current process.
* By using a %NULL value for the @pasid argument, this function can
* be used to simply validate that PASID support is available for the
* given device — i.e. that it is behind an IOMMU which has the
* requisite support, and is enabled.
* Page faults are handled transparently by the IOMMU code, and there
* should be no need for the device driver to be involved. If a page
* fault cannot be handled (i.e. is an invalid address rather than
* just needs paging in), then the page request will be completed by
* the core IOMMU code with appropriate status, and the device itself
* can then report the resulting fault to its driver via whatever
* mechanism is appropriate.
* Multiple calls from the same process may result in the same PASID
* being re-used. A reference count is kept.
extern int intel_svm_bind_mm(struct device *dev, int *pasid, int flags,
struct svm_dev_ops *ops);
* intel_svm_unbind_mm() - Unbind a specified PASID
* @dev: Device for which PASID was allocated
* @pasid: PASID value to be unbound
* This function allows a PASID to be retired when the device no
* longer requires access to the address space of a given process.
* If the use count for the PASID in question reaches zero, the
* PASID is revoked and may no longer be used by hardware.
* Device drivers are required to ensure that no access (including
* page requests) is currently outstanding for the PASID in question,
* before calling this function.
extern int intel_svm_unbind_mm(struct device *dev, int pasid);
* intel_svm_is_pasid_valid() - check if pasid is valid
* @dev: Device for which PASID was allocated
* @pasid: PASID value to be checked
* This function checks if the specified pasid is still valid. A
* valid pasid means the backing mm is still having a valid user.
* For kernel callers init_mm is always valid. for other mm, if mm->mm_users
* is non-zero, it is valid.
* returns -EINVAL if invalid pasid, 0 if pasid ref count is invalid
* 1 if pasid is valid.
extern int intel_svm_is_pasid_valid(struct device *dev, int pasid);
static inline int intel_svm_bind_mm(struct device *dev, int *pasid,
int flags, struct svm_dev_ops *ops)
return -ENOSYS;
static inline int intel_svm_unbind_mm(struct device *dev, int pasid)
static int intel_svm_is_pasid_valid(struct device *dev, int pasid)
return -EINVAL;
#define intel_svm_available(dev) (!intel_svm_bind_mm((dev), NULL, 0, NULL))
#endif /* __INTEL_SVM_H__ */