On Tue, 2024-10-15 at 20:24 -0700, Matthew Brost wrote:
Continued review:
> +/**
> + * drm_gpusvm_migrate_unmap_pages() - Unmap pages previously mapped
> for GPU SVM migration
> + * @dev: The device for which the pages were mapped
> + * @dma_addr: Array of DMA addresses corresponding to mapped pages
> + * @npages: Number of pages to unmap
> + * @dir: Direction of data transfer (e.g., DMA_BIDIRECTIONAL)
> + *
> + * This function unmaps previously mapped pages of memory for GPU
> Shared Virtual
> + * Memory (SVM). It iterates over each DMA address provided in
> @dma_addr, checks
> + * if it's valid and not already unmapped, and unmaps the
> corresponding page.
> + */
> +static void drm_gpusvm_migrate_unmap_pages(struct device *dev,
> + dma_addr_t *dma_addr,
> + unsigned long npages,
> + enum dma_data_direction
> dir)
> +{
> + unsigned long i;
> +
> + for (i = 0; i < npages; ++i) {
> + if (!dma_addr[i] || dma_mapping_error(dev,
> dma_addr[i]))
> + continue;
> +
> + dma_unmap_page(dev, dma_addr[i], PAGE_SIZE, dir);
> + }
> +}
> +
> +/**
> + * drm_gpusvm_migrate_to_devmem - Migrate GPU SVM range to device
> memory
> + * @gpusvm: Pointer to the GPU SVM structure
> + * @range: Pointer to the GPU SVM range structure
> + * @devmem_allocation: Pointer to the device memory allocation. The
> caller
> + * should hold a reference to the device memory
> allocation,
> + * which should be dropped via ops-
> >devmem_release or upon
> + * the failure of this function.
> + * @ctx: GPU SVM context
> + *
> + * This function migrates the specified GPU SVM range to device
> memory. It performs the
> + * necessary setup and invokes the driver-specific operations for
> migration to
> + * device memory. Upon successful return, @devmem_allocation can
> safely reference @range
> + * until ops->devmem_release is called which only upon successful
> return.
> + *
> + * Returns:
> + * 0 on success, negative error code on failure.
> + */
> +int drm_gpusvm_migrate_to_devmem(struct drm_gpusvm *gpusvm,
> + struct drm_gpusvm_range *range,
> + struct drm_gpusvm_devmem
> *devmem_allocation,
> + const struct drm_gpusvm_ctx *ctx)
> +{
> + const struct drm_gpusvm_devmem_ops *ops = devmem_allocation-
> >ops;
> + u64 start = range->va.start, end = range->va.end;
> + struct migrate_vma migrate = {
> + .start = start,
> + .end = end,
> + .pgmap_owner = gpusvm->device_private_page_owner,
> + .flags = MIGRATE_VMA_SELECT_SYSTEM,
> + };
> + struct mm_struct *mm = gpusvm->mm;
> + unsigned long i, npages = npages_in_range(start, end);
> + struct vm_area_struct *vas;
> + struct drm_gpusvm_zdd *zdd = NULL;
> + struct page **pages;
> + dma_addr_t *dma_addr;
> + void *buf;
> + int err;
> +
> + if (!range->flags.migrate_devmem)
> + return -EINVAL;
> +
> + if (!ops->populate_devmem_pfn || !ops->copy_to_devmem ||
> !ops->copy_to_ram)
> + return -EOPNOTSUPP;
> +
> + if (!mmget_not_zero(mm)) {
> + err = -EFAULT;
> + goto err_out;
> + }
> + mmap_read_lock(mm);
> +
> + vas = vma_lookup(mm, start);
> + if (!vas) {
> + err = -ENOENT;
> + goto err_mmunlock;
> + }
> +
> + if (end > vas->vm_end || start < vas->vm_start) {
> + err = -EINVAL;
> + goto err_mmunlock;
> + }
> +
> + if (!vma_is_anonymous(vas)) {
> + err = -EBUSY;
> + goto err_mmunlock;
> + }
> +
> + buf = kvcalloc(npages, 2 * sizeof(*migrate.src) +
> sizeof(*dma_addr) +
> + sizeof(*pages), GFP_KERNEL);
> + if (!buf) {
> + err = -ENOMEM;
> + goto err_mmunlock;
> + }
> + dma_addr = buf + (2 * sizeof(*migrate.src) * npages);
> + pages = buf + (2 * sizeof(*migrate.src) + sizeof(*dma_addr))
> * npages;
> +
> + zdd = drm_gpusvm_zdd_alloc(gpusvm-
> >device_private_page_owner);
> + if (!zdd) {
> + err = -ENOMEM;
> + goto err_free;
> + }
> +
> + migrate.vma = vas;
> + migrate.src = buf;
> + migrate.dst = migrate.src + npages;
> +
> + err = migrate_vma_setup(&migrate);
> + if (err)
> + goto err_free;
> +
> + /*
> + * FIXME: Below cases, !migrate.cpages and migrate.cpages !=
> npages, not
> + * always an error. Need to revisit possible cases and how
> to handle. We
> + * could prefault on migrate.cpages != npages via
> hmm_range_fault.
> + */
> +
> + if (!migrate.cpages) {
> + err = -EFAULT;
> + goto err_free;
> + }
> +
> + if (migrate.cpages != npages) {
> + err = -EBUSY;
> + goto err_finalize;
> + }
> +
> + err = ops->populate_devmem_pfn(devmem_allocation, npages,
> migrate.dst);
> + if (err)
> + goto err_finalize;
> +
> + err = drm_gpusvm_migrate_map_pages(devmem_allocation->dev,
> dma_addr,
> + migrate.src, npages,
> DMA_TO_DEVICE);
> + if (err)
> + goto err_finalize;
> +
> + for (i = 0; i < npages; ++i) {
> + struct page *page = pfn_to_page(migrate.dst[i]);
> +
> + pages[i] = page;
> + migrate.dst[i] = migrate_pfn(migrate.dst[i]);
> + drm_gpusvm_get_devmem_page(page, zdd);
> + }
> +
> + err = ops->copy_to_devmem(pages, dma_addr, npages);
> + if (err)
> + goto err_finalize;
> +
> + /* Upon success bind devmem allocation to range and zdd */
> + WRITE_ONCE(zdd->devmem_allocation, devmem_allocation); /*
> Owns ref */
> +
> +err_finalize:
> + if (err)
> + drm_gpusvm_migration_put_pages(npages, migrate.dst);
> + migrate_vma_pages(&migrate);
> + migrate_vma_finalize(&migrate);
> + drm_gpusvm_migrate_unmap_pages(devmem_allocation->dev,
> dma_addr, npages,
> + DMA_TO_DEVICE);
> +err_free:
> + if (zdd)
> + drm_gpusvm_zdd_put(zdd);
> + kvfree(buf);
> +err_mmunlock:
> + mmap_read_unlock(mm);
> + mmput(mm);
> +err_out:
> + return err;
> +}
> +
> +/**
> + * drm_gpusvm_migrate_populate_ram_pfn - Populate RAM PFNs for a VM
> area
> + * @vas: Pointer to the VM area structure, can be NULL
> + * @npages: Number of pages to populate
> + * @mpages: Number of pages to migrate
> + * @src_mpfn: Source array of migrate PFNs
> + * @mpfn: Array of migrate PFNs to populate
> + * @addr: Start address for PFN allocation
> + *
> + * This function populates the RAM migrate page frame numbers (PFNs)
> for the
> + * specified VM area structure. It allocates and locks pages in the
> VM area for
> + * RAM usage. If vas is non-NULL use alloc_page_vma for allocation,
> if NULL use
> + * alloc_page for allocation.
> + *
> + * Returns:
> + * 0 on success, negative error code on failure.
> + */
> +static int drm_gpusvm_migrate_populate_ram_pfn(struct vm_area_struct
> *vas,
> + unsigned long npages,
> + unsigned long
> *mpages,
> + unsigned long
> *src_mpfn,
> + unsigned long *mpfn,
> u64 addr)
> +{
> + unsigned long i;
> +
> + for (i = 0; i < npages; ++i, addr += PAGE_SIZE) {
> + struct page *page;
> +
> + if (!(src_mpfn[i] & MIGRATE_PFN_MIGRATE))
> + continue;
> +
> + if (vas)
> + page = alloc_page_vma(GFP_HIGHUSER, vas,
> addr);
> + else
> + page = alloc_page(GFP_HIGHUSER);
> +
> + if (!page)
> + return -ENOMEM;
> +
> + lock_page(page);
Allocating under page-locks seem a bit scary, but OTOH we're
recursively locking page-locks as well. Perhaps a comment on why this
is allowed.
Allocating and then trylocking with asserts as separate steps otherwise
would guarantee that we don't hit a deadlock without noticing but the
way it's currently coded seems to be common practice.
> + mpfn[i] = migrate_pfn(page_to_pfn(page));
> + ++*mpages;
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * drm_gpusvm_evict_to_ram - Evict GPU SVM range to RAM
> + * @devmem_allocation: Pointer to the device memory allocation
> + *
> + * Similar to __drm_gpusvm_migrate_to_ram but does not require mmap
> lock and
> + * migration done via migrate_device_* functions.
> + *
> + * Returns:
> + * 0 on success, negative error code on failure.
> + */
> +int drm_gpusvm_evict_to_ram(struct drm_gpusvm_devmem
> *devmem_allocation)
> +{
> + const struct drm_gpusvm_devmem_ops *ops = devmem_allocation-
> >ops;
> + unsigned long npages, mpages = 0;
> + struct page **pages;
> + unsigned long *src, *dst;
> + dma_addr_t *dma_addr;
> + void *buf;
> + int i, err = 0;
> +
> + npages = devmem_allocation->size >> PAGE_SHIFT;
> +
> +retry:
> + if (!mmget_not_zero(devmem_allocation->mm))
> + return -EFAULT;
> +
> + buf = kvcalloc(npages, 2 * sizeof(*src) + sizeof(*dma_addr)
> +
> + sizeof(*pages), GFP_KERNEL);
> + if (!buf) {
> + err = -ENOMEM;
> + goto err_out;
> + }
> + src = buf;
> + dst = buf + (sizeof(*src) * npages);
> + dma_addr = buf + (2 * sizeof(*src) * npages);
> + pages = buf + (2 * sizeof(*src) + sizeof(*dma_addr)) *
> npages;
> +
> + err = ops->populate_devmem_pfn(devmem_allocation, npages,
> src);
> + if (err)
> + goto err_free;
> +
> + err = migrate_device_prepopulated_range(src, npages);
> + if (err)
> + goto err_free;
> +
> + err = drm_gpusvm_migrate_populate_ram_pfn(NULL, npages,
> &mpages, src,
> + dst, 0);
> + if (err || !mpages)
> + goto err_finalize;
> +
> + err = drm_gpusvm_migrate_map_pages(devmem_allocation->dev,
> dma_addr,
> + dst, npages,
> DMA_FROM_DEVICE);
> + if (err)
> + goto err_finalize;
> +
> + for (i = 0; i < npages; ++i)
> + pages[i] = migrate_pfn_to_page(src[i]);
> +
> + err = ops->copy_to_ram(pages, dma_addr, npages);
> + if (err)
> + goto err_finalize;
> +
> +err_finalize:
> + if (err)
> + drm_gpusvm_migration_put_pages(npages, dst);
> + migrate_device_pages(src, dst, npages);
> + migrate_device_finalize(src, dst, npages);
> + drm_gpusvm_migrate_unmap_pages(devmem_allocation->dev,
> dma_addr, npages,
> + DMA_FROM_DEVICE);
> +err_free:
> + kvfree(buf);
> +err_out:
> + mmput_async(devmem_allocation->mm);
> + if (!err && !READ_ONCE(devmem_allocation->detached)) {
> + cond_resched();
> + goto retry;
> + }
> +
> + return err;
> +}
> +
> +/**
> + * __drm_gpusvm_migrate_to_ram - Migrate GPU SVM range to RAM
> (internal)
> + * @vas: Pointer to the VM area structure
> + * @device_private_page_owner: Device private pages owner
> + * @page: Pointer to the page for fault handling (can be NULL)
> + * @fault_addr: Fault address
> + * @size: Size of migration
> + *
> + * This internal function performs the migration of the specified
> GPU SVM range
> + * to RAM. It sets up the migration, populates + dma maps RAM PFNs,
> and
> + * invokes the driver-specific operations for migration to RAM.
> + *
> + * Returns:
> + * 0 on success, negative error code on failure.
> + */
> +static int __drm_gpusvm_migrate_to_ram(struct vm_area_struct *vas,
> + void
> *device_private_page_owner,
> + struct page *page, u64
> fault_addr,
> + u64 size)
> +{
> + struct migrate_vma migrate = {
> + .vma = vas,
> + .pgmap_owner = device_private_page_owner,
> + .flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE
> |
> + MIGRATE_VMA_SELECT_DEVICE_COHERENT,
> + .fault_page = page,
> + };
> + struct drm_gpusvm_zdd *zdd;
> + const struct drm_gpusvm_devmem_ops *ops;
> + struct device *dev;
> + unsigned long npages, mpages = 0;
> + struct page **pages;
> + dma_addr_t *dma_addr;
> + u64 start, end;
> + void *buf;
> + int i, err = 0;
> +
> + start = ALIGN_DOWN(fault_addr, size);
> + end = ALIGN(fault_addr + 1, size);
> +
> + /* Corner where VMA area struct has been partially unmapped
> */
> + if (start < vas->vm_start)
> + start = vas->vm_start;
> + if (end > vas->vm_end)
> + end = vas->vm_end;
> +
> + migrate.start = start;
> + migrate.end = end;
> + npages = npages_in_range(start, end);
> +
> + buf = kvcalloc(npages, 2 * sizeof(*migrate.src) +
> sizeof(*dma_addr) +
> + sizeof(*pages), GFP_KERNEL);
> + if (!buf) {
> + err = -ENOMEM;
> + goto err_out;
> + }
> + dma_addr = buf + (2 * sizeof(*migrate.src) * npages);
> + pages = buf + (2 * sizeof(*migrate.src) + sizeof(*dma_addr))
> * npages;
> +
> + migrate.vma = vas;
> + migrate.src = buf;
> + migrate.dst = migrate.src + npages;
> +
> + err = migrate_vma_setup(&migrate);
> + if (err)
> + goto err_free;
> +
> + /* Raced with another CPU fault, nothing to do */
> + if (!migrate.cpages)
> + goto err_free;
> +
> + if (!page) {
> + for (i = 0; i < npages; ++i) {
> + if (!(migrate.src[i] & MIGRATE_PFN_MIGRATE))
> + continue;
> +
> + page = migrate_pfn_to_page(migrate.src[i]);
> + break;
> + }
> +
> + if (!page)
> + goto err_finalize;
> + }
> + zdd = page->zone_device_data;
> + ops = zdd->devmem_allocation->ops;
> + dev = zdd->devmem_allocation->dev;
> +
> + err = drm_gpusvm_migrate_populate_ram_pfn(vas, npages,
> &mpages,
> + migrate.src,
> migrate.dst,
> + start);
> + if (err)
> + goto err_finalize;
> +
> + err = drm_gpusvm_migrate_map_pages(dev, dma_addr,
> migrate.dst, npages,
> + DMA_FROM_DEVICE);
> + if (err)
> + goto err_finalize;
> +
> + for (i = 0; i < npages; ++i)
> + pages[i] = migrate_pfn_to_page(migrate.src[i]);
> +
> + err = ops->copy_to_ram(pages, dma_addr, npages);
> + if (err)
> + goto err_finalize;
> +
> +err_finalize:
> + if (err)
> + drm_gpusvm_migration_put_pages(npages, migrate.dst);
> + migrate_vma_pages(&migrate);
> + migrate_vma_finalize(&migrate);
> + drm_gpusvm_migrate_unmap_pages(dev, dma_addr, npages,
> + DMA_FROM_DEVICE);
> +err_free:
> + kvfree(buf);
> +err_out:
> +
> + return err;
> +}
> +
> +/**
> + * drm_gpusvm_range_evict - Evict GPU SVM range
> + * @gpusvm: Pointer to the GPU SVM structure
> + * @range: Pointer to the GPU SVM range to be removed
> + *
> + * This function evicts the specified GPU SVM range.
> + */
> +void drm_gpusvm_range_evict(struct drm_gpusvm *gpusvm,
> + struct drm_gpusvm_range *range)
Although we discussed this one before. Ideally I think we'd want to be
able to migrate also other devices' pages. But need to consider device-
coherent pages.
> +{
> + struct mm_struct *mm = gpusvm->mm;
> + struct vm_area_struct *vas;
> +
> + if (!mmget_not_zero(mm))
> + return;
> +
> + mmap_read_lock(mm);
> + vas = vma_lookup(mm, range->va.start);
> + if (!vas)
> + goto unlock;
> +
> + __drm_gpusvm_migrate_to_ram(vas, gpusvm-
> >device_private_page_owner,
> + NULL, range->va.start,
> + range->va.end - range-
> >va.start);
> +unlock:
> + mmap_read_unlock(mm);
> + mmput(mm);
> +}
> +
> +/**
> + * drm_gpusvm_page_free - Put GPU SVM zone device data associated
> with a page
> + * @page: Pointer to the page
> + *
> + * This function is a callback used to put the GPU SVM zone device
> data
> + * associated with a page when it is being released.
> + */
> +static void drm_gpusvm_page_free(struct page *page)
> +{
> + drm_gpusvm_zdd_put(page->zone_device_data);
> +}
> +
> +/**
> + * drm_gpusvm_migrate_to_ram - Migrate GPU SVM range to RAM (page
> fault handler)
> + * @vmf: Pointer to the fault information structure
> + *
> + * This function is a page fault handler used to migrate a GPU SVM
> range to RAM.
> + * It retrieves the GPU SVM range information from the faulting page
> and invokes
> + * the internal migration function to migrate the range back to RAM.
> + *
> + * Returns:
> + * VM_FAULT_SIGBUS on failure, 0 on success.
> + */
> +static vm_fault_t drm_gpusvm_migrate_to_ram(struct vm_fault *vmf)
> +{
> + struct drm_gpusvm_zdd *zdd = vmf->page->zone_device_data;
> + int err;
... and this one only the pages belonging to the current pagemap.
> +
> + err = __drm_gpusvm_migrate_to_ram(vmf->vma,
> + zdd-
> >device_private_page_owner,
> + vmf->page, vmf->address,
> + zdd->devmem_allocation-
> >size);
> +
> + return err ? VM_FAULT_SIGBUS : 0;
> +}
> +
> +/**
> + * drm_gpusvm_pagemap_ops - Device page map operations for GPU SVM
> + */
> +static const struct dev_pagemap_ops drm_gpusvm_pagemap_ops = {
> + .page_free = drm_gpusvm_page_free,
> + .migrate_to_ram = drm_gpusvm_migrate_to_ram,
> +};
> +
> +/**
> + * drm_gpusvm_pagemap_ops_get - Retrieve GPU SVM device page map
> operations
> + *
> + * Returns:
> + * Pointer to the GPU SVM device page map operations structure.
> + */
> +const struct dev_pagemap_ops *drm_gpusvm_pagemap_ops_get(void)
> +{
> + return &drm_gpusvm_pagemap_ops;
> +}
> +
> +/**
> + * drm_gpusvm_has_mapping - Check if GPU SVM has mapping for the
> given address range
> + * @gpusvm: Pointer to the GPU SVM structure.
> + * @start: Start address
> + * @end: End address
> + *
> + * Returns:
> + * True if GPU SVM has mapping, False otherwise
> + */
> +bool drm_gpusvm_has_mapping(struct drm_gpusvm *gpusvm, u64 start,
> u64 end)
> +{
> + struct drm_gpusvm_notifier *notifier;
> +
> + drm_gpusvm_for_each_notifier(notifier, gpusvm, start, end) {
> + struct drm_gpusvm_range *range = NULL;
> +
> + drm_gpusvm_for_each_range(range, notifier, start,
> end)
> + return true;
> + }
> +
> + return false;
> +}
> diff --git a/drivers/gpu/drm/xe/drm_gpusvm.h
> b/drivers/gpu/drm/xe/drm_gpusvm.h
> new file mode 100644
> index 000000000000..15ec22d4f9a5
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/drm_gpusvm.h
> @@ -0,0 +1,447 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2024 Intel Corporation
> + */
> +
> +#ifndef __DRM_GPUSVM_H__
> +#define __DRM_GPUSVM_H__
> +
> +#include <linux/kref.h>
> +#include <linux/mmu_notifier.h>
> +#include <linux/workqueue.h>
> +
> +struct dev_pagemap_ops;
> +struct drm_device;
> +struct drm_gpusvm;
> +struct drm_gpusvm_notifier;
> +struct drm_gpusvm_ops;
> +struct drm_gpusvm_range;
> +struct drm_gpusvm_devmem;
> +struct drm_pagemap;
> +struct drm_pagemap_dma_addr;
> +
> +/**
> + * struct drm_gpusvm_devmem_ops - Operations structure for GPU SVM
> device memory
> + *
> + * This structure defines the operations for GPU Shared Virtual
> Memory (SVM)
> + * device memory. These operations are provided by the GPU driver to
> manage device memory
> + * allocations and perform operations such as migration between
> device memory and system
> + * RAM.
> + */
> +struct drm_gpusvm_devmem_ops {
> + /**
> + * @devmem_release: Release device memory allocation
> (optional)
> + * @devmem_allocation: device memory allocation
> + *
> + * This function shall release device memory allocation and
> expects to drop a
NIT: Consider "Release device memory..." rather than "This function
shall release..." (general comment).
> + * reference to device memory allocation.
> + */
> + void (*devmem_release)(struct drm_gpusvm_devmem
> *devmem_allocation);
> +
> + /**
> + * @populate_devmem_pfn: Populate device memory PFN
> (required for migration)
> + * @devmem_allocation: device memory allocation
> + * @npages: Number of pages to populate
> + * @pfn: Array of page frame numbers to populate
> + *
> + * This function shall populate device memory page frame
> numbers (PFN).
> + *
> + * Returns:
> + * 0 on success, a negative error code on failure.
> + */
> + int (*populate_devmem_pfn)(struct drm_gpusvm_devmem
> *devmem_allocation,
> + unsigned long npages, unsigned long
> *pfn);
> +
> + /**
> + * @copy_to_devmem: Copy to device memory (required for
> migration)
> + * @pages: Pointer to array of device memory pages
> (destination)
> + * @dma_addr: Pointer to array of DMA addresses (source)
> + * @npages: Number of pages to copy
> + *
> + * This function shall copy pages to device memory.
> + *
> + * Returns:
> + * 0 on success, a negative error code on failure.
> + */
> + int (*copy_to_devmem)(struct page **pages,
> + dma_addr_t *dma_addr,
> + unsigned long npages);
> +
> + /**
> + * @copy_to_ram: Copy to system RAM (required for migration)
> + * @pages: Pointer to array of device memory pages (source)
> + * @dma_addr: Pointer to array of DMA addresses
> (destination)
> + * @npages: Number of pages to copy
> + *
> + * This function shall copy pages to system RAM.
> + *
> + * Returns:
> + * 0 on success, a negative error code on failure.
> + */
> + int (*copy_to_ram)(struct page **pages,
> + dma_addr_t *dma_addr,
> + unsigned long npages);
> +};
> +
> +/**
> + * struct drm_gpusvm_devmem - Structure representing a GPU SVM
> device memory allocation
> + *
> + * @dev: Pointer to the device structure which device memory
> allocation belongs to
> + * @mm: Pointer to the mm_struct for the address space
> + * @ops: Pointer to the operations structure for GPU SVM device
> memory
> + * @dpagemap: The struct drm_pagemap of the pages this allocation
> belongs to.
> + * @size: Size of device memory allocation
> + * @detached: device memory allocations is detached from device
> pages
> + */
> +struct drm_gpusvm_devmem {
> + struct device *dev;
> + struct mm_struct *mm;
> + const struct drm_gpusvm_devmem_ops *ops;
> + struct drm_pagemap *dpagemap;
> + size_t size;
> + bool detached;
> +};
> +
> +/**
> + * struct drm_gpusvm_ops - Operations structure for GPU SVM
> + *
> + * This structure defines the operations for GPU Shared Virtual
> Memory (SVM).
> + * These operations are provided by the GPU driver to manage SVM
> ranges and
> + * notifiers.
> + */
> +struct drm_gpusvm_ops {
> + /**
> + * @notifier_alloc: Allocate a GPU SVM notifier (optional)
> + *
> + * This function shall allocate a GPU SVM notifier.
> + *
> + * Returns:
> + * Pointer to the allocated GPU SVM notifier on success,
> NULL on failure.
> + */
> + struct drm_gpusvm_notifier *(*notifier_alloc)(void);
> +
> + /**
> + * @notifier_free: Free a GPU SVM notifier (optional)
> + * @notifier: Pointer to the GPU SVM notifier to be freed
> + *
> + * This function shall free a GPU SVM notifier.
> + */
> + void (*notifier_free)(struct drm_gpusvm_notifier *notifier);
> +
> + /**
> + * @range_alloc: Allocate a GPU SVM range (optional)
> + * @gpusvm: Pointer to the GPU SVM
> + *
> + * This function shall allocate a GPU SVM range.
> + *
> + * Returns:
> + * Pointer to the allocated GPU SVM range on success, NULL
> on failure.
> + */
> + struct drm_gpusvm_range *(*range_alloc)(struct drm_gpusvm
> *gpusvm);
> +
> + /**
> + * @range_free: Free a GPU SVM range (optional)
> + * @range: Pointer to the GPU SVM range to be freed
> + *
> + * This function shall free a GPU SVM range.
> + */
> + void (*range_free)(struct drm_gpusvm_range *range);
> +
> + /**
> + * @invalidate: Invalidate GPU SVM notifier (required)
> + * @gpusvm: Pointer to the GPU SVM
> + * @notifier: Pointer to the GPU SVM notifier
> + * @mmu_range: Pointer to the mmu_notifier_range structure
> + *
> + * This function shall invalidate the GPU page tables. It
> can safely
> + * walk the notifier range RB tree/list in this function.
> Called while
> + * holding the notifier lock.
> + */
> + void (*invalidate)(struct drm_gpusvm *gpusvm,
> + struct drm_gpusvm_notifier *notifier,
> + const struct mmu_notifier_range
> *mmu_range);
> +};
> +
> +/**
> + * struct drm_gpusvm_notifier - Structure representing a GPU SVM
> notifier
> + *
> + * @gpusvm: Pointer to the GPU SVM structure
> + * @notifier: MMU interval notifier
> + * @interval: Interval for the notifier
> + * @rb: Red-black tree node for the parent GPU SVM structure
> notifier tree
> + * @root: Cached root node of the RB tree containing ranges
> + * @range_list: List head containing of ranges in the same order
> they appear in
> + * interval tree. This is useful to keep iterating
> ranges while
> + * doing modifications to RB tree.
> + * @flags.removed: Flag indicating whether the MMU interval notifier
> has been
> + * removed
Please also document the nested fields.
> + *
> + * This structure represents a GPU SVM notifier.
> + */
> +struct drm_gpusvm_notifier {
> + struct drm_gpusvm *gpusvm;
> + struct mmu_interval_notifier notifier;
> + struct {
> + u64 start;
> + u64 end;
> + } interval;
> + struct {
> + struct rb_node node;
> + struct list_head entry;
> + u64 __subtree_last;
> + } rb;
> + struct rb_root_cached root;
> + struct list_head range_list;
> + struct {
> + u32 removed : 1;
> + } flags;
> +};
> +
> +/**
> + * struct drm_gpusvm_range - Structure representing a GPU SVM range
> + *
> + * @gpusvm: Pointer to the GPU SVM structure
> + * @notifier: Pointer to the GPU SVM notifier
> + * @refcount: Reference count for the range
> + * @rb: Red-black tree node for the parent GPU SVM notifier
> structure range tree
> + * @va: Virtual address range
> + * @notifier_seq: Notifier sequence number of the range's pages
> + * @dma_addr: DMA address array
> + * @dpagemap: The struct drm_pagemap of the device pages we're dma-
> mapping.
> + * Note this is assuming only one drm_pagemap per range is allowed.
> + * @flags.migrate_devmem: Flag indicating whether the range can be
> migrated to device memory
> + * @flags.unmapped: Flag indicating if the range has been unmapped
> + * @flags.partial_unmap: Flag indicating if the range has been
> partially unmapped
> + * @flags.has_devmem_pages: Flag indicating if the range has devmem
> pages
> + * @flags.has_dma_mapping: Flag indicating if the range has a DMA
> mapping
> + *
> + * This structure represents a GPU SVM range used for tracking
> memory ranges
> + * mapped in a DRM device.
> + */
Also here.
> +struct drm_gpusvm_range {
> + struct drm_gpusvm *gpusvm;
> + struct drm_gpusvm_notifier *notifier;
> + struct kref refcount;
> + struct {
> + struct rb_node node;
> + struct list_head entry;
> + u64 __subtree_last;
> + } rb;
> + struct {
> + u64 start;
> + u64 end;
> + } va;
> + unsigned long notifier_seq;
> + struct drm_pagemap_dma_addr *dma_addr;
> + struct drm_pagemap *dpagemap;
> + struct {
> + /* All flags below must be set upon creation */
> + u16 migrate_devmem : 1;
> + /* All flags below must be set / cleared under
> notifier lock */
> + u16 unmapped : 1;
> + u16 partial_unmap : 1;
> + u16 has_devmem_pages : 1;
> + u16 has_dma_mapping : 1;
> + } flags;
> +};
> +
> +/**
> + * struct drm_gpusvm - GPU SVM structure
> + *
> + * @name: Name of the GPU SVM
> + * @drm: Pointer to the DRM device structure
> + * @mm: Pointer to the mm_struct for the address space
> + * @device_private_page_owner: Device private pages owner
> + * @mm_start: Start address of GPU SVM
> + * @mm_range: Range of the GPU SVM
> + * @notifier_size: Size of individual notifiers
> + * @ops: Pointer to the operations structure for GPU SVM
> + * @chunk_sizes: Pointer to the array of chunk sizes used in range
> allocation.
> + * Entries should be powers of 2 in descending order.
> + * @num_chunks: Number of chunks
> + * @notifier_lock: Read-write semaphore for protecting notifier
> operations
> + * @root: Cached root node of the Red-Black tree containing GPU SVM
> notifiers
> + * @notifier_list: list head containing of notifiers in the same
> order they
> + * appear in interval tree. This is useful to keep
> iterating
> + * notifiers while doing modifications to RB tree.
> + *
> + * This structure represents a GPU SVM (Shared Virtual Memory) used
> for tracking
> + * memory ranges mapped in a DRM (Direct Rendering Manager) device.
> + *
> + * No reference counting is provided, as this is expected to be
> embedded in the
> + * driver VM structure along with the struct drm_gpuvm, which
> handles reference
> + * counting.
> + */
> +struct drm_gpusvm {
> + const char *name;
> + struct drm_device *drm;
> + struct mm_struct *mm;
> + void *device_private_page_owner;
> + u64 mm_start;
> + u64 mm_range;
Possibly consider using unsigned long for cpu virtual addresses, since
that's typically done elsewhere.
GPU virtual addresses should remain 64-bit, though.
> + u64 notifier_size;
> + const struct drm_gpusvm_ops *ops;
> + const u64 *chunk_sizes;
> + int num_chunks;
> + struct rw_semaphore notifier_lock;
> + struct rb_root_cached root;
> + struct list_head notifier_list;
> +};
> +
> +/**
> + * struct drm_gpusvm_ctx - DRM GPU SVM context
> + *
> + * @in_notifier: entering from a MMU notifier
> + * @read_only: operating on read-only memory
> + * @devmem_possible: possible to use device memory
> + * @check_pages: check pages and only create range for pages faulted
> in
> + *
> + * Context that is DRM GPUSVM is operating in (i.e. user arguments).
> + */
> +struct drm_gpusvm_ctx {
> + u32 in_notifier :1;
> + u32 read_only :1;
> + u32 devmem_possible :1;
> + u32 check_pages :1;
> +};
> +
> +int drm_gpusvm_init(struct drm_gpusvm *gpusvm,
> + const char *name, struct drm_device *drm,
> + struct mm_struct *mm, void
> *device_private_page_owner,
> + u64 mm_start, u64 mm_range, u64 notifier_size,
> + const struct drm_gpusvm_ops *ops,
> + const u64 *chunk_sizes, int num_chunks);
> +void drm_gpusvm_fini(struct drm_gpusvm *gpusvm);
> +void drm_gpusvm_free(struct drm_gpusvm *gpusvm);
> +
> +struct drm_gpusvm_range *
> +drm_gpusvm_range_find_or_insert(struct drm_gpusvm *gpusvm, u64
> fault_addr,
> + u64 gpuva_start, u64 gpuva_end,
> + const struct drm_gpusvm_ctx *ctx);
> +void drm_gpusvm_range_remove(struct drm_gpusvm *gpusvm,
> + struct drm_gpusvm_range *range);
> +void drm_gpusvm_range_evict(struct drm_gpusvm *gpusvm,
> + struct drm_gpusvm_range *range);
> +
> +struct drm_gpusvm_range *
> +drm_gpusvm_range_get(struct drm_gpusvm_range *range);
> +void drm_gpusvm_range_put(struct drm_gpusvm_range *range);
> +
> +bool drm_gpusvm_range_pages_valid(struct drm_gpusvm *gpusvm,
> + struct drm_gpusvm_range *range);
> +
> +int drm_gpusvm_range_get_pages(struct drm_gpusvm *gpusvm,
> + struct drm_gpusvm_range *range,
> + const struct drm_gpusvm_ctx *ctx);
> +void drm_gpusvm_range_unmap_pages(struct drm_gpusvm *gpusvm,
> + struct drm_gpusvm_range *range,
> + const struct drm_gpusvm_ctx *ctx);
There is some newline inconsistency between declarations. I think the
recommended coding style is to use a newline in-between.
> +
> +int drm_gpusvm_migrate_to_devmem(struct drm_gpusvm *gpusvm,
> + struct drm_gpusvm_range *range,
> + struct drm_gpusvm_devmem
> *devmem_allocation,
> + const struct drm_gpusvm_ctx *ctx);
> +int drm_gpusvm_evict_to_ram(struct drm_gpusvm_devmem
> *devmem_allocation);
> +
> +const struct dev_pagemap_ops *drm_gpusvm_pagemap_ops_get(void);
> +
> +bool drm_gpusvm_has_mapping(struct drm_gpusvm *gpusvm, u64 start,
> u64 end);
> +
> +struct drm_gpusvm_range *
> +drm_gpusvm_range_find(struct drm_gpusvm_notifier *notifier, u64
> start, u64 end);
> +
> +/**
> + * drm_gpusvm_notifier_lock - Lock GPU SVM notifier
> + * @gpusvm__: Pointer to the GPU SVM structure.
> + *
> + * Abstract client usage GPU SVM notifier lock, take lock
> + */
> +#define drm_gpusvm_notifier_lock(gpusvm__) \
> + down_read(&(gpusvm__)->notifier_lock)
> +
> +/**
> + * drm_gpusvm_notifier_unlock - Unlock GPU SVM notifier
> + * @gpusvm__: Pointer to the GPU SVM structure.
> + *
> + * Abstract client usage GPU SVM notifier lock, drop lock
> + */
> +#define drm_gpusvm_notifier_unlock(gpusvm__) \
> + up_read(&(gpusvm__)->notifier_lock)
> +
> +/**
> + * __drm_gpusvm_range_next - Get the next GPU SVM range in the list
> + * @range: a pointer to the current GPU SVM range
> + *
> + * Return: A pointer to the next drm_gpusvm_range if available, or
> NULL if the
> + * current range is the last one or if the input range is
> NULL.
> + */
> +static inline struct drm_gpusvm_range *
> +__drm_gpusvm_range_next(struct drm_gpusvm_range *range)
> +{
> + if (range && !list_is_last(&range->rb.entry,
> + &range->notifier->range_list))
> + return list_next_entry(range, rb.entry);
> +
> + return NULL;
> +}
> +
> +/**
> + * drm_gpusvm_for_each_range - Iterate over GPU SVM ranges in a
> notifier
> + * @range__: Iterator variable for the ranges. If set, it indicates
> the start of
> + * the iterator. If NULL, call drm_gpusvm_range_find() to
> get the range.
> + * @notifier__: Pointer to the GPU SVM notifier
> + * @start__: Start address of the range
> + * @end__: End address of the range
> + *
> + * This macro is used to iterate over GPU SVM ranges in a notifier.
> It is safe
> + * to use while holding the driver SVM lock or the notifier lock.
> + */
> +#define drm_gpusvm_for_each_range(range__, notifier__, start__,
> end__) \
> + for ((range__) = (range__)
> ?: \
> + drm_gpusvm_range_find((notifier__), (start__),
> (end__)); \
> + (range__) && (range__->va.start <
> (end__)); \
> + (range__) = __drm_gpusvm_range_next(range__))
> +
> +/**
> + * drm_gpusvm_range_set_unmapped - Mark a GPU SVM range as unmapped
> + * @range: Pointer to the GPU SVM range structure.
> + * @mmu_range: Pointer to the MMU notifier range structure.
> + *
> + * This function marks a GPU SVM range as unmapped and sets the
> partial_unmap flag
> + * if the range partially falls within the provided MMU notifier
> range.
> + */
> +static inline void
> +drm_gpusvm_range_set_unmapped(struct drm_gpusvm_range *range,
> + const struct mmu_notifier_range
> *mmu_range)
> +{
> + lockdep_assert_held_write(&range->gpusvm->notifier_lock);
> +
> + range->flags.unmapped = true;
> + if (range->va.start < mmu_range->start ||
> + range->va.end > mmu_range->end)
> + range->flags.partial_unmap = true;
> +}
Inlines are really only useful for performance reasons, and that's not
the case here.
> +
> +/**
> + * drm_gpusvm_devmem_init - Initialize a GPU SVM device memory
> allocation
> + *
> + * @dev: Pointer to the device structure which device memory
> allocation belongs to
> + * @mm: Pointer to the mm_struct for the address space
> + * @ops: Pointer to the operations structure for GPU SVM device
> memory
> + * @dpagemap: The struct drm_pagemap we're allocating from.
> + * @size: Size of device memory allocation
> + */
> +static inline void
> +drm_gpusvm_devmem_init(struct drm_gpusvm_devmem *devmem_allocation,
> + struct device *dev, struct mm_struct *mm,
> + const struct drm_gpusvm_devmem_ops *ops,
> + struct drm_pagemap *dpagemap, size_t size)
> +{
> + devmem_allocation->dev = dev;
> + devmem_allocation->mm = mm;
> + devmem_allocation->ops = ops;
> + devmem_allocation->dpagemap = dpagemap;
> + devmem_allocation->size = size;
> +}
Same here?
> +
> +#endif /* __DRM_GPUSVM_H__ */
> --
> 2.34.1
Thanks,
Thomas
