[PATCH v4 1/2] drm/xe: Introduce helper to populate userptr
Ghimiray, Himal Prasad
himal.prasad.ghimiray at intel.com
Mon Apr 8 06:12:15 UTC 2024
On 06-04-2024 02:59, Matthew Brost wrote:
> On Sat, Apr 06, 2024 at 12:35:07AM +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)
>> v4: Remove the dummy function for xe_hmm_userptr_populate_range
>> since CONFIG_HMM_MIRROR is needed. (Matt)
>> Change variable names start/end to userptr_start/userptr_end.(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>
> Reviewed-by: Matthew Brost<matthew.brost at intel.com>
Thank you, Matt, for the review.
>
>> 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 | 11 ++
>> 4 files changed, 267 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..2c32dc46f7d4
>> --- /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 userptr_start = xe_vma_userptr(vma);
>> + u64 userptr_end = userptr_start + xe_vma_size(vma);
>> + 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(userptr_start, userptr_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 = userptr_start;
>> + hmm_range.end = userptr_end;
>> + hmm_range.dev_private_owner = vm->xe;
>> +
>> + while (true) {
>> + hmm_range.notifier_seq = mmu_interval_read_begin(&userptr->notifier);
>> +
>> + 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..909dc2bdcd97
>> --- /dev/null
>> +++ b/drivers/gpu/drm/xe/xe_hmm.h
>> @@ -0,0 +1,11 @@
>> +/* SPDX-License-Identifier: MIT
>> + *
>> + * Copyright © 2024 Intel Corporation
>> + */
>> +
>> +#include <linux/types.h>
>> +
>> +struct xe_userptr_vma;
>> +
>> +int xe_hmm_userptr_populate_range(struct xe_userptr_vma *uvma, bool is_mm_mmap_locked);
>> +void xe_hmm_userptr_free_sg(struct xe_userptr_vma *uvma);
>> --
>> 2.25.1
>>
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