[PATCH v3 1/2] drm/xe: Introduce helper to populate userptr
Matthew Brost
matthew.brost at intel.com
Fri Apr 5 01:07:55 UTC 2024
On Thu, Apr 04, 2024 at 11:46:30AM +0530, Himal Prasad Ghimiray wrote:
> From: Oak Zeng <oak.zeng at intel.com>
>
> Introduce a helper function xe_userptr_populate_range to populate
> a a userptr range. This functions calls hmm_range_fault to read
> CPU page tables and populate all pfns/pages of this virtual address
> range.
>
> If the populated page is system memory page, dma-mapping is performed
> to get a dma-address which can be used later for GPU to access pages.
>
> If the populated page is device private page, we calculate the dpa (
> device physical address) of the page. This will be handled in future
> patches.
>
> The dma-address or dpa is then saved in userptr's sg table. This is
> prepare work to replace the get_user_pages_fast code in userptr code
> path.
>
> v1: Address review comments:
> separate a npage_in_range function (Matt)
> reparameterize function xe_userptr_populate_range function (Matt)
> move mmu_interval_read_begin() call into while loop (Thomas)
> s/mark_range_accessed/xe_mark_range_accessed (Thomas)
> use set_page_dirty_lock (vs set_page_dirty) (Thomas)
> move a few checking in xe_vma_userptr_pin_pages to hmm.c (Matt)
> v2: Remove device private page support. Only support system
> pages for now. use dma-map-sg rather than dma-map-page (Matt/Thomas)
> v3: Address review comments:
> Squash patch "drm/xe: Introduce a helper to free sg table" to current
> patch (Matt)
> start and end addresses are already page aligned (Matt)
> Do mmap_read_lock and mmap_read_unlock for hmm_range_fault incase of
> non system allocator call. (Matt)
> Drop kthread_use_mm and kthread_unuse_mm. (Matt)
> No need of kernel-doc for static functions.(Matt)
> Modify function names. (Matt)
> Free sgtable incase of dma_map_sgtable failure.(Matt)
> Modify loop for hmm_range_fault.(Matt)
>
> Signed-off-by: Oak Zeng <oak.zeng at intel.com>
> Co-developed-by: Niranjana Vishwanathapura <niranjana.vishwanathapura at intel.com>
> Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura at intel.com>
> Cc: Matthew Brost <matthew.brost at intel.com>
> Cc: Thomas Hellström <thomas.hellstrom at intel.com>
> Cc: Brian Welty <brian.welty at intel.com>
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
> ---
> drivers/gpu/drm/xe/Kconfig | 1 +
> drivers/gpu/drm/xe/Makefile | 2 +
> drivers/gpu/drm/xe/xe_hmm.c | 253 ++++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/xe/xe_hmm.h | 18 +++
> 4 files changed, 274 insertions(+)
> create mode 100644 drivers/gpu/drm/xe/xe_hmm.c
> create mode 100644 drivers/gpu/drm/xe/xe_hmm.h
>
> diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig
> index 1a556d087e63..449a1ecbc92a 100644
> --- a/drivers/gpu/drm/xe/Kconfig
> +++ b/drivers/gpu/drm/xe/Kconfig
> @@ -41,6 +41,7 @@ config DRM_XE
> select MMU_NOTIFIER
> select WANT_DEV_COREDUMP
> select AUXILIARY_BUS
> + select HMM_MIRROR
> help
> Experimental driver for Intel Xe series GPUs
>
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index 21316ee47026..07031b5ba977 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -146,6 +146,8 @@ xe-y += xe_bb.o \
> xe_wa.o \
> xe_wopcm.o
>
> +xe-$(CONFIG_HMM_MIRROR) += xe_hmm.o
> +
> # graphics hardware monitoring (HWMON) support
> xe-$(CONFIG_HWMON) += xe_hwmon.o
>
> diff --git a/drivers/gpu/drm/xe/xe_hmm.c b/drivers/gpu/drm/xe/xe_hmm.c
> new file mode 100644
> index 000000000000..d7a11896ad72
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_hmm.c
> @@ -0,0 +1,253 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2024 Intel Corporation
> + */
> +
> +#include <linux/scatterlist.h>
> +#include <linux/mmu_notifier.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/memremap.h>
> +#include <linux/swap.h>
> +#include <linux/hmm.h>
> +#include <linux/mm.h>
> +#include "xe_hmm.h"
> +#include "xe_vm.h"
> +#include "xe_bo.h"
> +
> +static u64 xe_npages_in_range(unsigned long start, unsigned long end)
> +{
> + return (end - start) >> PAGE_SHIFT;
> +}
> +
> +/*
> + * xe_mark_range_accessed() - mark a range is accessed, so core mm
> + * have such information for memory eviction or write back to
> + * hard disk
> + *
> + * @range: the range to mark
> + * @write: if write to this range, we mark pages in this range
> + * as dirty
> + */
> +static void xe_mark_range_accessed(struct hmm_range *range, bool write)
> +{
> + struct page *page;
> + u64 i, npages;
> +
> + npages = xe_npages_in_range(range->start, range->end);
> + for (i = 0; i < npages; i++) {
> + page = hmm_pfn_to_page(range->hmm_pfns[i]);
> + if (write)
> + set_page_dirty_lock(page);
> +
> + mark_page_accessed(page);
> + }
> +}
> +
> +/*
> + * xe_build_sg() - build a scatter gather table for all the physical pages/pfn
> + * in a hmm_range. dma-map pages if necessary. dma-address is save in sg table
> + * and will be used to program GPU page table later.
> + *
> + * @xe: the xe device who will access the dma-address in sg table
> + * @range: the hmm range that we build the sg table from. range->hmm_pfns[]
> + * has the pfn numbers of pages that back up this hmm address range.
> + * @st: pointer to the sg table.
> + * @write: whether we write to this range. This decides dma map direction
> + * for system pages. If write we map it bi-diretional; otherwise
> + * DMA_TO_DEVICE
> + *
> + * All the contiguous pfns will be collapsed into one entry in
> + * the scatter gather table. This is for the purpose of efficiently
> + * programming GPU page table.
> + *
> + * The dma_address in the sg table will later be used by GPU to
> + * access memory. So if the memory is system memory, we need to
> + * do a dma-mapping so it can be accessed by GPU/DMA.
> + *
> + * FIXME: This function currently only support pages in system
> + * memory. If the memory is GPU local memory (of the GPU who
> + * is going to access memory), we need gpu dpa (device physical
> + * address), and there is no need of dma-mapping. This is TBD.
> + *
> + * FIXME: dma-mapping for peer gpu device to access remote gpu's
> + * memory. Add this when you support p2p
> + *
> + * This function allocates the storage of the sg table. It is
> + * caller's responsibility to free it calling sg_free_table.
> + *
> + * Returns 0 if successful; -ENOMEM if fails to allocate memory
> + */
> +static int xe_build_sg(struct xe_device *xe, struct hmm_range *range,
> + struct sg_table *st, bool write)
> +{
> + struct device *dev = xe->drm.dev;
> + struct page **pages;
> + u64 i, npages;
> + int ret;
> +
> + npages = xe_npages_in_range(range->start, range->end);
> + pages = kvmalloc_array(npages, sizeof(*pages), GFP_KERNEL);
> + if (!pages)
> + return -ENOMEM;
> +
> + for (i = 0; i < npages; i++) {
> + pages[i] = hmm_pfn_to_page(range->hmm_pfns[i]);
> + xe_assert(xe, !is_device_private_page(pages[i]));
> + }
> +
> + ret = sg_alloc_table_from_pages_segment(st, pages, npages, 0, npages << PAGE_SHIFT,
> + xe_sg_segment_size(dev), GFP_KERNEL);
> + if (ret)
> + goto free_pages;
> +
> + ret = dma_map_sgtable(dev, st, write ? DMA_BIDIRECTIONAL : DMA_TO_DEVICE,
> + DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_NO_KERNEL_MAPPING);
> + if (ret) {
> + sg_free_table(st);
> + st = NULL;
> + }
> +
> +free_pages:
> + kvfree(pages);
> + return ret;
> +}
> +
> +/*
> + * xe_hmm_userptr_free_sg() - Free the scatter gather table of userptr
> + *
> + * @uvma: the userptr vma which hold the scatter gather table
> + *
> + * With function xe_userptr_populate_range, we allocate storage of
> + * the userptr sg table. This is a helper function to free this
> + * sg table, and dma unmap the address in the table.
> + */
> +void xe_hmm_userptr_free_sg(struct xe_userptr_vma *uvma)
> +{
> + struct xe_userptr *userptr = &uvma->userptr;
> + struct xe_vma *vma = &uvma->vma;
> + bool write = !xe_vma_read_only(vma);
> + struct xe_vm *vm = xe_vma_vm(vma);
> + struct xe_device *xe = vm->xe;
> + struct device *dev = xe->drm.dev;
> +
> + xe_assert(xe, userptr->sg);
> + dma_unmap_sgtable(dev, userptr->sg,
> + write ? DMA_BIDIRECTIONAL : DMA_TO_DEVICE, 0);
> +
> + sg_free_table(userptr->sg);
> + userptr->sg = NULL;
> +}
> +
> +/**
> + * xe_hmm_userptr_populate_range() - Populate physical pages of a virtual
> + * address range
> + *
> + * @uvma: userptr vma which has information of the range to populate.
> + * @is_mm_mmap_locked: True if mmap_read_lock is already acquired by caller.
> + *
> + * This function populate the physical pages of a virtual
> + * address range. The populated physical pages is saved in
> + * userptr's sg table. It is similar to get_user_pages but call
> + * hmm_range_fault.
> + *
> + * This function also read mmu notifier sequence # (
> + * mmu_interval_read_begin), for the purpose of later
> + * comparison (through mmu_interval_read_retry).
> + *
> + * This must be called with mmap read or write lock held.
> + *
> + * This function allocates the storage of the userptr sg table.
> + * It is caller's responsibility to free it calling sg_free_table.
> + *
> + * returns: 0 for succuss; negative error no on failure
> + */
> +int xe_hmm_userptr_populate_range(struct xe_userptr_vma *uvma,
> + bool is_mm_mmap_locked)
> +{
> + unsigned long timeout =
> + jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
> + unsigned long *pfns, flags = HMM_PFN_REQ_FAULT;
> + struct xe_userptr *userptr;
> + struct xe_vma *vma = &uvma->vma;
> + u64 start = xe_vma_userptr(vma);
> + u64 end = start + xe_vma_size(vma);
Nit: xe_vma_end
> + struct xe_vm *vm = xe_vma_vm(vma);
> + struct hmm_range hmm_range;
> + bool write = !xe_vma_read_only(vma);
> + unsigned long notifier_seq;
> + u64 npages;
> + int ret;
> +
> + userptr = &uvma->userptr;
> +
> + if (is_mm_mmap_locked)
> + mmap_assert_locked(userptr->notifier.mm);
> +
> + if (vma->gpuva.flags & XE_VMA_DESTROYED)
> + return 0;
> +
> + notifier_seq = mmu_interval_read_begin(&userptr->notifier);
> + if (notifier_seq == userptr->notifier_seq)
> + return 0;
> +
> + if (userptr->sg)
> + xe_hmm_userptr_free_sg(uvma);
> +
> + npages = xe_npages_in_range(start, end);
> + pfns = kvmalloc_array(npages, sizeof(*pfns), GFP_KERNEL);
> + if (unlikely(!pfns))
> + return -ENOMEM;
> +
> + if (write)
> + flags |= HMM_PFN_REQ_WRITE;
> +
> + if (!mmget_not_zero(userptr->notifier.mm)) {
> + ret = -EFAULT;
> + goto free_pfns;
> + }
> +
> + hmm_range.default_flags = flags;
> + hmm_range.hmm_pfns = pfns;
> + hmm_range.notifier = &userptr->notifier;
> + hmm_range.start = start;
> + hmm_range.end = end;
> + hmm_range.dev_private_owner = vm->xe;
> +
> + while (true) {
> + hmm_range.notifier_seq = mmu_interval_read_begin(&userptr->notifier);
Nit: This could be set above in this code:
notifier_seq = mmu_interval_read_begin(&userptr->notifier);
if (notifier_seq == userptr->notifier_seq)
return 0;
i.e. drop local notifier_seq and set hmm_range.notifier_seq...
Then reset before continue in the if (ret == -EBUSY) function.
> +
> + if (!is_mm_mmap_locked)
> + mmap_read_lock(userptr->notifier.mm);
> +
> + ret = hmm_range_fault(&hmm_range);
> +
> + if (!is_mm_mmap_locked)
> + mmap_read_unlock(userptr->notifier.mm);
> +
> + if (ret == -EBUSY) {
> + if (time_after(jiffies, timeout))
> + break;
> +
> + continue;
> + }
> + break;
> + }
> +
> + mmput(userptr->notifier.mm);
> +
> + if (ret)
> + goto free_pfns;
> +
> + ret = xe_build_sg(vm->xe, &hmm_range, &userptr->sgt, write);
> + if (ret)
> + goto free_pfns;
> +
> + xe_mark_range_accessed(&hmm_range, write);
> + userptr->sg = &userptr->sgt;
> + userptr->notifier_seq = hmm_range.notifier_seq;
> +
> +free_pfns:
> + kvfree(pfns);
> + return ret;
> +}
> +
> diff --git a/drivers/gpu/drm/xe/xe_hmm.h b/drivers/gpu/drm/xe/xe_hmm.h
> new file mode 100644
> index 000000000000..40250e3f84d1
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_hmm.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: MIT
> + *
> + * Copyright © 2024 Intel Corporation
> + */
> +
> +#include <linux/types.h>
> +
> +struct xe_userptr_vma;
> +
> +#if IS_ENABLED(CONFIG_HMM_MIRROR)
> +int xe_hmm_userptr_populate_range(struct xe_userptr_vma *uvma, bool is_mm_mmap_locked);
> +#else
> +static inline int xe_hmm_userptr_populate_range(struct xe_userptr_vma *uvma, bool is_mm_mmap_locked)
> +{
> + return -ENODEV;
> +}
> +#endif
Mentioned that I don't think is needed in last rev as our driver require
CONFIG_HMM_MIRROR to be built.
Matt
> +void xe_hmm_userptr_free_sg(struct xe_userptr_vma *uvma);
> --
> 2.25.1
>
More information about the Intel-xe
mailing list