![John Hubbard](/assets/img/avatar_default.png)
This code was using get_user_pages_fast(), in a "Case 2" scenario (DMA/RDMA), using the categorization from [1]. That means that it's time to convert the get_user_pages_fast() + put_page() calls to pin_user_pages_fast() + unpin_user_pages() calls. There is some helpful background in [2]: basically, this is a small part of fixing a long-standing disconnect between pinning pages, and file systems' use of those pages. [1] Documentation/core-api/pin_user_pages.rst [2] "Explicit pinning of user-space pages": https://lwn.net/Articles/807108/ Cc: Xu Yilun <yilun.xu@intel.com> Cc: Wu Hao <hao.wu@intel.com> Cc: Moritz Fischer <mdf@kernel.org> Cc: linux-fpga@vger.kernel.org Signed-off-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Wu Hao <hao.wu@intel.com> Signed-off-by: Moritz Fischer <mdf@kernel.org>
406 lines
10 KiB
C
406 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Driver for FPGA Accelerated Function Unit (AFU) DMA Region Management
|
|
*
|
|
* Copyright (C) 2017-2018 Intel Corporation, Inc.
|
|
*
|
|
* Authors:
|
|
* Wu Hao <hao.wu@intel.com>
|
|
* Xiao Guangrong <guangrong.xiao@linux.intel.com>
|
|
*/
|
|
|
|
#include <linux/dma-mapping.h>
|
|
#include <linux/sched/signal.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/mm.h>
|
|
|
|
#include "dfl-afu.h"
|
|
|
|
void afu_dma_region_init(struct dfl_feature_platform_data *pdata)
|
|
{
|
|
struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
|
|
|
|
afu->dma_regions = RB_ROOT;
|
|
}
|
|
|
|
/**
|
|
* afu_dma_pin_pages - pin pages of given dma memory region
|
|
* @pdata: feature device platform data
|
|
* @region: dma memory region to be pinned
|
|
*
|
|
* Pin all the pages of given dfl_afu_dma_region.
|
|
* Return 0 for success or negative error code.
|
|
*/
|
|
static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata,
|
|
struct dfl_afu_dma_region *region)
|
|
{
|
|
int npages = region->length >> PAGE_SHIFT;
|
|
struct device *dev = &pdata->dev->dev;
|
|
int ret, pinned;
|
|
|
|
ret = account_locked_vm(current->mm, npages, true);
|
|
if (ret)
|
|
return ret;
|
|
|
|
region->pages = kcalloc(npages, sizeof(struct page *), GFP_KERNEL);
|
|
if (!region->pages) {
|
|
ret = -ENOMEM;
|
|
goto unlock_vm;
|
|
}
|
|
|
|
pinned = pin_user_pages_fast(region->user_addr, npages, FOLL_WRITE,
|
|
region->pages);
|
|
if (pinned < 0) {
|
|
ret = pinned;
|
|
goto free_pages;
|
|
} else if (pinned != npages) {
|
|
ret = -EFAULT;
|
|
goto unpin_pages;
|
|
}
|
|
|
|
dev_dbg(dev, "%d pages pinned\n", pinned);
|
|
|
|
return 0;
|
|
|
|
unpin_pages:
|
|
unpin_user_pages(region->pages, pinned);
|
|
free_pages:
|
|
kfree(region->pages);
|
|
unlock_vm:
|
|
account_locked_vm(current->mm, npages, false);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* afu_dma_unpin_pages - unpin pages of given dma memory region
|
|
* @pdata: feature device platform data
|
|
* @region: dma memory region to be unpinned
|
|
*
|
|
* Unpin all the pages of given dfl_afu_dma_region.
|
|
* Return 0 for success or negative error code.
|
|
*/
|
|
static void afu_dma_unpin_pages(struct dfl_feature_platform_data *pdata,
|
|
struct dfl_afu_dma_region *region)
|
|
{
|
|
long npages = region->length >> PAGE_SHIFT;
|
|
struct device *dev = &pdata->dev->dev;
|
|
|
|
unpin_user_pages(region->pages, npages);
|
|
kfree(region->pages);
|
|
account_locked_vm(current->mm, npages, false);
|
|
|
|
dev_dbg(dev, "%ld pages unpinned\n", npages);
|
|
}
|
|
|
|
/**
|
|
* afu_dma_check_continuous_pages - check if pages are continuous
|
|
* @region: dma memory region
|
|
*
|
|
* Return true if pages of given dma memory region have continuous physical
|
|
* address, otherwise return false.
|
|
*/
|
|
static bool afu_dma_check_continuous_pages(struct dfl_afu_dma_region *region)
|
|
{
|
|
int npages = region->length >> PAGE_SHIFT;
|
|
int i;
|
|
|
|
for (i = 0; i < npages - 1; i++)
|
|
if (page_to_pfn(region->pages[i]) + 1 !=
|
|
page_to_pfn(region->pages[i + 1]))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* dma_region_check_iova - check if memory area is fully contained in the region
|
|
* @region: dma memory region
|
|
* @iova: address of the dma memory area
|
|
* @size: size of the dma memory area
|
|
*
|
|
* Compare the dma memory area defined by @iova and @size with given dma region.
|
|
* Return true if memory area is fully contained in the region, otherwise false.
|
|
*/
|
|
static bool dma_region_check_iova(struct dfl_afu_dma_region *region,
|
|
u64 iova, u64 size)
|
|
{
|
|
if (!size && region->iova != iova)
|
|
return false;
|
|
|
|
return (region->iova <= iova) &&
|
|
(region->length + region->iova >= iova + size);
|
|
}
|
|
|
|
/**
|
|
* afu_dma_region_add - add given dma region to rbtree
|
|
* @pdata: feature device platform data
|
|
* @region: dma region to be added
|
|
*
|
|
* Return 0 for success, -EEXIST if dma region has already been added.
|
|
*
|
|
* Needs to be called with pdata->lock heold.
|
|
*/
|
|
static int afu_dma_region_add(struct dfl_feature_platform_data *pdata,
|
|
struct dfl_afu_dma_region *region)
|
|
{
|
|
struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
|
|
struct rb_node **new, *parent = NULL;
|
|
|
|
dev_dbg(&pdata->dev->dev, "add region (iova = %llx)\n",
|
|
(unsigned long long)region->iova);
|
|
|
|
new = &afu->dma_regions.rb_node;
|
|
|
|
while (*new) {
|
|
struct dfl_afu_dma_region *this;
|
|
|
|
this = container_of(*new, struct dfl_afu_dma_region, node);
|
|
|
|
parent = *new;
|
|
|
|
if (dma_region_check_iova(this, region->iova, region->length))
|
|
return -EEXIST;
|
|
|
|
if (region->iova < this->iova)
|
|
new = &((*new)->rb_left);
|
|
else if (region->iova > this->iova)
|
|
new = &((*new)->rb_right);
|
|
else
|
|
return -EEXIST;
|
|
}
|
|
|
|
rb_link_node(®ion->node, parent, new);
|
|
rb_insert_color(®ion->node, &afu->dma_regions);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* afu_dma_region_remove - remove given dma region from rbtree
|
|
* @pdata: feature device platform data
|
|
* @region: dma region to be removed
|
|
*
|
|
* Needs to be called with pdata->lock heold.
|
|
*/
|
|
static void afu_dma_region_remove(struct dfl_feature_platform_data *pdata,
|
|
struct dfl_afu_dma_region *region)
|
|
{
|
|
struct dfl_afu *afu;
|
|
|
|
dev_dbg(&pdata->dev->dev, "del region (iova = %llx)\n",
|
|
(unsigned long long)region->iova);
|
|
|
|
afu = dfl_fpga_pdata_get_private(pdata);
|
|
rb_erase(®ion->node, &afu->dma_regions);
|
|
}
|
|
|
|
/**
|
|
* afu_dma_region_destroy - destroy all regions in rbtree
|
|
* @pdata: feature device platform data
|
|
*
|
|
* Needs to be called with pdata->lock heold.
|
|
*/
|
|
void afu_dma_region_destroy(struct dfl_feature_platform_data *pdata)
|
|
{
|
|
struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
|
|
struct rb_node *node = rb_first(&afu->dma_regions);
|
|
struct dfl_afu_dma_region *region;
|
|
|
|
while (node) {
|
|
region = container_of(node, struct dfl_afu_dma_region, node);
|
|
|
|
dev_dbg(&pdata->dev->dev, "del region (iova = %llx)\n",
|
|
(unsigned long long)region->iova);
|
|
|
|
rb_erase(node, &afu->dma_regions);
|
|
|
|
if (region->iova)
|
|
dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
|
|
region->iova, region->length,
|
|
DMA_BIDIRECTIONAL);
|
|
|
|
if (region->pages)
|
|
afu_dma_unpin_pages(pdata, region);
|
|
|
|
node = rb_next(node);
|
|
kfree(region);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* afu_dma_region_find - find the dma region from rbtree based on iova and size
|
|
* @pdata: feature device platform data
|
|
* @iova: address of the dma memory area
|
|
* @size: size of the dma memory area
|
|
*
|
|
* It finds the dma region from the rbtree based on @iova and @size:
|
|
* - if @size == 0, it finds the dma region which starts from @iova
|
|
* - otherwise, it finds the dma region which fully contains
|
|
* [@iova, @iova+size)
|
|
* If nothing is matched returns NULL.
|
|
*
|
|
* Needs to be called with pdata->lock held.
|
|
*/
|
|
struct dfl_afu_dma_region *
|
|
afu_dma_region_find(struct dfl_feature_platform_data *pdata, u64 iova, u64 size)
|
|
{
|
|
struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
|
|
struct rb_node *node = afu->dma_regions.rb_node;
|
|
struct device *dev = &pdata->dev->dev;
|
|
|
|
while (node) {
|
|
struct dfl_afu_dma_region *region;
|
|
|
|
region = container_of(node, struct dfl_afu_dma_region, node);
|
|
|
|
if (dma_region_check_iova(region, iova, size)) {
|
|
dev_dbg(dev, "find region (iova = %llx)\n",
|
|
(unsigned long long)region->iova);
|
|
return region;
|
|
}
|
|
|
|
if (iova < region->iova)
|
|
node = node->rb_left;
|
|
else if (iova > region->iova)
|
|
node = node->rb_right;
|
|
else
|
|
/* the iova region is not fully covered. */
|
|
break;
|
|
}
|
|
|
|
dev_dbg(dev, "region with iova %llx and size %llx is not found\n",
|
|
(unsigned long long)iova, (unsigned long long)size);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* afu_dma_region_find_iova - find the dma region from rbtree by iova
|
|
* @pdata: feature device platform data
|
|
* @iova: address of the dma region
|
|
*
|
|
* Needs to be called with pdata->lock held.
|
|
*/
|
|
static struct dfl_afu_dma_region *
|
|
afu_dma_region_find_iova(struct dfl_feature_platform_data *pdata, u64 iova)
|
|
{
|
|
return afu_dma_region_find(pdata, iova, 0);
|
|
}
|
|
|
|
/**
|
|
* afu_dma_map_region - map memory region for dma
|
|
* @pdata: feature device platform data
|
|
* @user_addr: address of the memory region
|
|
* @length: size of the memory region
|
|
* @iova: pointer of iova address
|
|
*
|
|
* Map memory region defined by @user_addr and @length, and return dma address
|
|
* of the memory region via @iova.
|
|
* Return 0 for success, otherwise error code.
|
|
*/
|
|
int afu_dma_map_region(struct dfl_feature_platform_data *pdata,
|
|
u64 user_addr, u64 length, u64 *iova)
|
|
{
|
|
struct dfl_afu_dma_region *region;
|
|
int ret;
|
|
|
|
/*
|
|
* Check Inputs, only accept page-aligned user memory region with
|
|
* valid length.
|
|
*/
|
|
if (!PAGE_ALIGNED(user_addr) || !PAGE_ALIGNED(length) || !length)
|
|
return -EINVAL;
|
|
|
|
/* Check overflow */
|
|
if (user_addr + length < user_addr)
|
|
return -EINVAL;
|
|
|
|
region = kzalloc(sizeof(*region), GFP_KERNEL);
|
|
if (!region)
|
|
return -ENOMEM;
|
|
|
|
region->user_addr = user_addr;
|
|
region->length = length;
|
|
|
|
/* Pin the user memory region */
|
|
ret = afu_dma_pin_pages(pdata, region);
|
|
if (ret) {
|
|
dev_err(&pdata->dev->dev, "failed to pin memory region\n");
|
|
goto free_region;
|
|
}
|
|
|
|
/* Only accept continuous pages, return error else */
|
|
if (!afu_dma_check_continuous_pages(region)) {
|
|
dev_err(&pdata->dev->dev, "pages are not continuous\n");
|
|
ret = -EINVAL;
|
|
goto unpin_pages;
|
|
}
|
|
|
|
/* As pages are continuous then start to do DMA mapping */
|
|
region->iova = dma_map_page(dfl_fpga_pdata_to_parent(pdata),
|
|
region->pages[0], 0,
|
|
region->length,
|
|
DMA_BIDIRECTIONAL);
|
|
if (dma_mapping_error(dfl_fpga_pdata_to_parent(pdata), region->iova)) {
|
|
dev_err(&pdata->dev->dev, "failed to map for dma\n");
|
|
ret = -EFAULT;
|
|
goto unpin_pages;
|
|
}
|
|
|
|
*iova = region->iova;
|
|
|
|
mutex_lock(&pdata->lock);
|
|
ret = afu_dma_region_add(pdata, region);
|
|
mutex_unlock(&pdata->lock);
|
|
if (ret) {
|
|
dev_err(&pdata->dev->dev, "failed to add dma region\n");
|
|
goto unmap_dma;
|
|
}
|
|
|
|
return 0;
|
|
|
|
unmap_dma:
|
|
dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
|
|
region->iova, region->length, DMA_BIDIRECTIONAL);
|
|
unpin_pages:
|
|
afu_dma_unpin_pages(pdata, region);
|
|
free_region:
|
|
kfree(region);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* afu_dma_unmap_region - unmap dma memory region
|
|
* @pdata: feature device platform data
|
|
* @iova: dma address of the region
|
|
*
|
|
* Unmap dma memory region based on @iova.
|
|
* Return 0 for success, otherwise error code.
|
|
*/
|
|
int afu_dma_unmap_region(struct dfl_feature_platform_data *pdata, u64 iova)
|
|
{
|
|
struct dfl_afu_dma_region *region;
|
|
|
|
mutex_lock(&pdata->lock);
|
|
region = afu_dma_region_find_iova(pdata, iova);
|
|
if (!region) {
|
|
mutex_unlock(&pdata->lock);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (region->in_use) {
|
|
mutex_unlock(&pdata->lock);
|
|
return -EBUSY;
|
|
}
|
|
|
|
afu_dma_region_remove(pdata, region);
|
|
mutex_unlock(&pdata->lock);
|
|
|
|
dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
|
|
region->iova, region->length, DMA_BIDIRECTIONAL);
|
|
afu_dma_unpin_pages(pdata, region);
|
|
kfree(region);
|
|
|
|
return 0;
|
|
}
|