[PATCH 1/5] drm/xe/svm: Remap and provide memmap backing for GPU vram
Welty, Brian
brian.welty at intel.com
Fri Mar 15 01:45:37 UTC 2024
Hi Oak,
On 3/13/2024 8:35 PM, Oak Zeng wrote:
> Memory remap GPU vram using devm_memremap_pages, so each GPU vram
> page is backed by a struct page.
>
> Those struct pages are created to allow hmm migrate buffer b/t
> GPU vram and CPU system memory using existing Linux migration
> mechanism (i.e., migrating b/t CPU system memory and hard disk).
>
> This is prepare work to enable svm (shared virtual memory) through
> Linux kernel hmm framework. The memory remap's page map type is set
> to MEMORY_DEVICE_PRIVATE for now. This means even though each GPU
> vram page get a struct page and can be mapped in CPU page table,
> but such pages are treated as GPU's private resource, so CPU can't
> access them. If CPU access such page, a page fault is triggered
> and page will be migrate to system memory.
>
> For GPU device which supports coherent memory protocol b/t CPU and
> GPU (such as CXL and CAPI protocol), we can remap device memory as
> MEMORY_DEVICE_COHERENT. This is TBD.
>
> 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>
> ---
> drivers/gpu/drm/xe/Makefile | 3 +-
> drivers/gpu/drm/xe/xe_device_types.h | 9 +++
> drivers/gpu/drm/xe/xe_mmio.c | 8 +++
> drivers/gpu/drm/xe/xe_svm.h | 14 +++++
> drivers/gpu/drm/xe/xe_svm_devmem.c | 91 ++++++++++++++++++++++++++++
> 5 files changed, 124 insertions(+), 1 deletion(-)
> create mode 100644 drivers/gpu/drm/xe/xe_svm.h
> create mode 100644 drivers/gpu/drm/xe/xe_svm_devmem.c
>
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index c531210695db..840467080e59 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -142,7 +142,8 @@ xe-y += xe_bb.o \
> xe_vram_freq.o \
> xe_wait_user_fence.o \
> xe_wa.o \
> - xe_wopcm.o
> + xe_wopcm.o \
> + xe_svm_devmem.o
Minor, but maintainers want above alphabetically sorted.
>
> # graphics hardware monitoring (HWMON) support
> xe-$(CONFIG_HWMON) += xe_hwmon.o
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index 9785eef2e5a4..f27c3bee8ce7 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -99,6 +99,15 @@ struct xe_mem_region {
> resource_size_t actual_physical_size;
> /** @mapping: pointer to VRAM mappable space */
> void __iomem *mapping;
> + /** @pagemap: Used to remap device memory as ZONE_DEVICE */
> + struct dev_pagemap pagemap;
> + /**
> + * @hpa_base: base host physical address
> + *
> + * This is generated when remap device memory as ZONE_DEVICE
> + */
> + resource_size_t hpa_base;
> +
> };
>
> /**
> diff --git a/drivers/gpu/drm/xe/xe_mmio.c b/drivers/gpu/drm/xe/xe_mmio.c
> index e3db3a178760..0d795394bc4c 100644
> --- a/drivers/gpu/drm/xe/xe_mmio.c
> +++ b/drivers/gpu/drm/xe/xe_mmio.c
> @@ -22,6 +22,7 @@
> #include "xe_module.h"
> #include "xe_sriov.h"
> #include "xe_tile.h"
> +#include "xe_svm.h"
>
> #define XEHP_MTCFG_ADDR XE_REG(0x101800)
> #define TILE_COUNT REG_GENMASK(15, 8)
> @@ -286,6 +287,7 @@ int xe_mmio_probe_vram(struct xe_device *xe)
> }
>
> io_size -= min_t(u64, tile_size, io_size);
> + xe_svm_devm_add(tile, &tile->mem.vram);
I think slightly more appropriate call site for this might be
xe_tile_init_noalloc(), as that function states it is preparing tile
for VRAM allocations.
Also, I mention because we might like the flexiblity in future to call
this once for xe_device.mem.vram, instead of calling for each tile,
and easier to handle that in xe_tile.c instead of xe_mmio.c.
Related comment below.
> }
>
> xe->mem.vram.actual_physical_size = total_size;
> @@ -354,10 +356,16 @@ void xe_mmio_probe_tiles(struct xe_device *xe)
> static void mmio_fini(struct drm_device *drm, void *arg)
> {
> struct xe_device *xe = arg;
> + struct xe_tile *tile;
> + u8 id;
>
> pci_iounmap(to_pci_dev(xe->drm.dev), xe->mmio.regs);
> if (xe->mem.vram.mapping)
> iounmap(xe->mem.vram.mapping);
> +
> + for_each_tile(tile, xe, id)
> + xe_svm_devm_remove(xe, &tile->mem.vram);
> +
> }
>
> static int xe_verify_lmem_ready(struct xe_device *xe)
> diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h
> new file mode 100644
> index 000000000000..09f9afb0e7d4
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_svm.h
> @@ -0,0 +1,14 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2023 Intel Corporation
> + */
> +
> +#ifndef __XE_SVM_H
> +#define __XE_SVM_H
> +
> +#include "xe_device_types.h"
> +
> +int xe_svm_devm_add(struct xe_tile *tile, struct xe_mem_region *mem);
> +void xe_svm_devm_remove(struct xe_device *xe, struct xe_mem_region *mem);
> +
> +#endif
> diff --git a/drivers/gpu/drm/xe/xe_svm_devmem.c b/drivers/gpu/drm/xe/xe_svm_devmem.c
> new file mode 100644
> index 000000000000..63b7a1961cc6
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_svm_devmem.c
> @@ -0,0 +1,91 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2023 Intel Corporation
> + */
> +
> +#include <linux/mm_types.h>
> +#include <linux/sched/mm.h>
> +
> +#include "xe_device_types.h"
> +#include "xe_trace.h"
> +#include "xe_svm.h"
> +
> +
> +static vm_fault_t xe_devm_migrate_to_ram(struct vm_fault *vmf)
> +{
> + return 0;
> +}
> +
> +static void xe_devm_page_free(struct page *page)
> +{
> +}
> +
> +static const struct dev_pagemap_ops xe_devm_pagemap_ops = {
> + .page_free = xe_devm_page_free,
> + .migrate_to_ram = xe_devm_migrate_to_ram,
> +};
> +
> +/**
> + * xe_svm_devm_add: Remap and provide memmap backing for device memory
Do we really need 'svm' in function name?
> + * @tile: tile that the memory region blongs to
We might like flexibility in future to call this once for
xe_device.mem.vram, instead of calling for each tile.
So can we remove the tile argument, and just pass the xe_device pointer
and tile->id ?
> + * @mr: memory region to remap
> + *
> + * This remap device memory to host physical address space and create
> + * struct page to back device memory
> + *
> + * Return: 0 on success standard error code otherwise
> + */
> +int xe_svm_devm_add(struct xe_tile *tile, struct xe_mem_region *mr)
> +{
> + struct device *dev = &to_pci_dev(tile->xe->drm.dev)->dev;
> + struct resource *res;
> + void *addr;
> + int ret;
> +
> + res = devm_request_free_mem_region(dev, &iomem_resource,
> + mr->usable_size);
> + if (IS_ERR(res)) {
> + ret = PTR_ERR(res);
> + return ret;
> + }
> +
> + mr->pagemap.type = MEMORY_DEVICE_PRIVATE;
> + mr->pagemap.range.start = res->start;
> + mr->pagemap.range.end = res->end;
> + mr->pagemap.nr_range = 1;
> + mr->pagemap.ops = &xe_devm_pagemap_ops;
> + mr->pagemap.owner = tile->xe->drm.dev;
> + addr = devm_memremap_pages(dev, &mr->pagemap);
> + if (IS_ERR(addr)) {
> + devm_release_mem_region(dev, res->start, resource_size(res));
> + ret = PTR_ERR(addr);
> + drm_err(&tile->xe->drm, "Failed to remap tile %d memory, errno %d\n",
> + tile->id, ret);
> + return ret;
> + }
> + mr->hpa_base = res->start;
> +
> + drm_info(&tile->xe->drm, "Added tile %d memory [%llx-%llx] to devm, remapped to %pr\n",
> + tile->id, mr->io_start, mr->io_start + mr->usable_size, res);
> + return 0;
> +}
> +
> +/**
> + * xe_svm_devm_remove: Unmap device memory and free resources
> + * @xe: xe device
> + * @mr: memory region to remove
> + */
> +void xe_svm_devm_remove(struct xe_device *xe, struct xe_mem_region *mr)
> +{
> + /*FIXME: below cause a kernel hange during moduel remove*/
> +#if 0
> + struct device *dev = &to_pci_dev(xe->drm.dev)->dev;
> +
> + if (mr->hpa_base) {
> + devm_memunmap_pages(dev, &mr->pagemap);
> + devm_release_mem_region(dev, mr->pagemap.range.start,
> + mr->pagemap.range.end - mr->pagemap.range.start +1);
> + }
> +#endif
> +}
> +
More information about the Intel-xe
mailing list