134 lines
4.6 KiB
C
134 lines
4.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright © 2015 Intel Corporation.
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*
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* Authors: David Woodhouse <David.Woodhouse@intel.com>
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*/
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#ifndef __INTEL_SVM_H__
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#define __INTEL_SVM_H__
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struct device;
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struct svm_dev_ops {
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void (*fault_cb)(struct device *dev, int pasid, u64 address,
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void *private, int rwxp, int response);
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};
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/* Values for rxwp in fault_cb callback */
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#define SVM_REQ_READ (1<<3)
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#define SVM_REQ_WRITE (1<<2)
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#define SVM_REQ_EXEC (1<<1)
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#define SVM_REQ_PRIV (1<<0)
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/*
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* The SVM_FLAG_PRIVATE_PASID flag requests a PASID which is *not* the "main"
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* PASID for the current process. Even if a PASID already exists, a new one
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* will be allocated. And the PASID allocated with SVM_FLAG_PRIVATE_PASID
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* will not be given to subsequent callers. This facility allows a driver to
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* disambiguate between multiple device contexts which access the same MM,
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* if there is no other way to do so. It should be used sparingly, if at all.
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*/
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#define SVM_FLAG_PRIVATE_PASID (1<<0)
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/*
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* The SVM_FLAG_SUPERVISOR_MODE flag requests a PASID which can be used only
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* for access to kernel addresses. No IOTLB flushes are automatically done
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* for kernel mappings; it is valid only for access to the kernel's static
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* 1:1 mapping of physical memory — not to vmalloc or even module mappings.
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* A future API addition may permit the use of such ranges, by means of an
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* explicit IOTLB flush call (akin to the DMA API's unmap method).
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*
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* It is unlikely that we will ever hook into flush_tlb_kernel_range() to
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* do such IOTLB flushes automatically.
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*/
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#define SVM_FLAG_SUPERVISOR_MODE (1<<1)
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#ifdef CONFIG_INTEL_IOMMU_SVM
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/**
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* intel_svm_bind_mm() - Bind the current process to a PASID
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* @dev: Device to be granted access
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* @pasid: Address for allocated PASID
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* @flags: Flags. Later for requesting supervisor mode, etc.
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* @ops: Callbacks to device driver
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*
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* This function attempts to enable PASID support for the given device.
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* If the @pasid argument is non-%NULL, a PASID is allocated for access
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* to the MM of the current process.
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*
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* By using a %NULL value for the @pasid argument, this function can
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* be used to simply validate that PASID support is available for the
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* given device — i.e. that it is behind an IOMMU which has the
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* requisite support, and is enabled.
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*
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* Page faults are handled transparently by the IOMMU code, and there
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* should be no need for the device driver to be involved. If a page
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* fault cannot be handled (i.e. is an invalid address rather than
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* just needs paging in), then the page request will be completed by
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* the core IOMMU code with appropriate status, and the device itself
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* can then report the resulting fault to its driver via whatever
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* mechanism is appropriate.
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*
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* Multiple calls from the same process may result in the same PASID
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* being re-used. A reference count is kept.
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*/
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extern int intel_svm_bind_mm(struct device *dev, int *pasid, int flags,
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struct svm_dev_ops *ops);
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/**
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* intel_svm_unbind_mm() - Unbind a specified PASID
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* @dev: Device for which PASID was allocated
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* @pasid: PASID value to be unbound
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*
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* This function allows a PASID to be retired when the device no
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* longer requires access to the address space of a given process.
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*
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* If the use count for the PASID in question reaches zero, the
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* PASID is revoked and may no longer be used by hardware.
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*
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* Device drivers are required to ensure that no access (including
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* page requests) is currently outstanding for the PASID in question,
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* before calling this function.
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*/
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extern int intel_svm_unbind_mm(struct device *dev, int pasid);
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/**
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* intel_svm_is_pasid_valid() - check if pasid is valid
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* @dev: Device for which PASID was allocated
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* @pasid: PASID value to be checked
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*
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* This function checks if the specified pasid is still valid. A
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* valid pasid means the backing mm is still having a valid user.
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* For kernel callers init_mm is always valid. for other mm, if mm->mm_users
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* is non-zero, it is valid.
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*
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* returns -EINVAL if invalid pasid, 0 if pasid ref count is invalid
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* 1 if pasid is valid.
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*/
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extern int intel_svm_is_pasid_valid(struct device *dev, int pasid);
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#else /* CONFIG_INTEL_IOMMU_SVM */
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static inline int intel_svm_bind_mm(struct device *dev, int *pasid,
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int flags, struct svm_dev_ops *ops)
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{
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return -ENOSYS;
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}
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static inline int intel_svm_unbind_mm(struct device *dev, int pasid)
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{
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BUG();
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}
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static int intel_svm_is_pasid_valid(struct device *dev, int pasid)
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{
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return -EINVAL;
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}
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#endif /* CONFIG_INTEL_IOMMU_SVM */
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#define intel_svm_available(dev) (!intel_svm_bind_mm((dev), NULL, 0, NULL))
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#endif /* __INTEL_SVM_H__ */
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