Commit 17ffdc48 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jason Gunthorpe
Browse files

mm: simplify device private page handling in hmm_range_fault 

Remove the HMM_PFN_DEVICE_PRIVATE flag, no driver has ever set this flag
on input, and the only place that uses it on output can be trivially
changed to use is_device_private_page().

This removes the ability to request that device_private pages are faulted
back into system memory.

Link: https://lore.kernel.org/r/20200316193216.920734-4-hch@lst.de


Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJason Gunthorpe <jgg@mellanox.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
parent 800bb1c8

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c

+0 −1
Original line number Diff line number Diff line
@@ -776,7 +776,6 @@ struct amdgpu_ttm_tt { 
static const uint64_t hmm_range_flags[HMM_PFN_FLAG_MAX] = {

	(1 << 0), /* HMM_PFN_VALID */

	(1 << 1), /* HMM_PFN_WRITE */

	0 /* HMM_PFN_DEVICE_PRIVATE */

};



static const uint64_t hmm_range_values[HMM_PFN_VALUE_MAX] = {

drivers/gpu/drm/nouveau/nouveau_dmem.c

+3 −2
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 


#include <nvif/class.h>

#include <nvif/object.h>

#include <nvif/if000c.h>

#include <nvif/if500b.h>

#include <nvif/if900b.h>
@@ -692,9 +693,8 @@ nouveau_dmem_convert_pfn(struct nouveau_drm *drm, 
		if (page == NULL)

			continue;



		if (!(range->pfns[i] & range->flags[HMM_PFN_DEVICE_PRIVATE])) {

		if (!is_device_private_page(page))

			continue;

		}



		if (!nouveau_dmem_page(drm, page)) {

			WARN(1, "Some unknown device memory !\n");
@@ -705,5 +705,6 @@ nouveau_dmem_convert_pfn(struct nouveau_drm *drm, 
		addr = nouveau_dmem_page_addr(page);

		range->pfns[i] &= ((1UL << range->pfn_shift) - 1);

		range->pfns[i] |= (addr >> PAGE_SHIFT) << range->pfn_shift;

		range->pfns[i] |= NVIF_VMM_PFNMAP_V0_VRAM;

	}

}

drivers/gpu/drm/nouveau/nouveau_svm.c

+0 −1
Original line number Diff line number Diff line
@@ -367,7 +367,6 @@ static const u64 
nouveau_svm_pfn_flags[HMM_PFN_FLAG_MAX] = {

	[HMM_PFN_VALID         ] = NVIF_VMM_PFNMAP_V0_V,

	[HMM_PFN_WRITE         ] = NVIF_VMM_PFNMAP_V0_W,

	[HMM_PFN_DEVICE_PRIVATE] = NVIF_VMM_PFNMAP_V0_VRAM,

};



static const u64

include/linux/hmm.h

+0 −2
Original line number Diff line number Diff line
@@ -74,7 +74,6 @@ 
 * Flags:

 * HMM_PFN_VALID: pfn is valid. It has, at least, read permission.

 * HMM_PFN_WRITE: CPU page table has write permission set

 * HMM_PFN_DEVICE_PRIVATE: private device memory (ZONE_DEVICE)

 *

 * The driver provides a flags array for mapping page protections to device

 * PTE bits. If the driver valid bit for an entry is bit 3,
@@ -86,7 +85,6 @@ 
enum hmm_pfn_flag_e {

	HMM_PFN_VALID = 0,

	HMM_PFN_WRITE,

	HMM_PFN_DEVICE_PRIVATE,

	HMM_PFN_FLAG_MAX

};

mm/hmm.c

+5 −20
Original line number Diff line number Diff line
@@ -116,15 +116,6 @@ static inline void hmm_pte_need_fault(const struct hmm_vma_walk *hmm_vma_walk, 
	/* We aren't ask to do anything ... */

	if (!(pfns & range->flags[HMM_PFN_VALID]))

		return;

	/* If this is device memory then only fault if explicitly requested */

	if ((cpu_flags & range->flags[HMM_PFN_DEVICE_PRIVATE])) {

		/* Do we fault on device memory ? */

		if (pfns & range->flags[HMM_PFN_DEVICE_PRIVATE]) {

			*write_fault = pfns & range->flags[HMM_PFN_WRITE];

			*fault = true;

		}

		return;

	}



	/* If CPU page table is not valid then we need to fault */

	*fault = !(cpu_flags & range->flags[HMM_PFN_VALID]);
@@ -262,21 +253,15 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, 
		swp_entry_t entry = pte_to_swp_entry(pte);



		/*

		 * This is a special swap entry, ignore migration, use

		 * device and report anything else as error.

		 * Never fault in device private pages pages, but just report

		 * the PFN even if not present.

		 */

		if (is_device_private_entry(entry)) {

			cpu_flags = range->flags[HMM_PFN_VALID] |

				range->flags[HMM_PFN_DEVICE_PRIVATE];

			cpu_flags |= is_write_device_private_entry(entry) ?

				range->flags[HMM_PFN_WRITE] : 0;

			hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,

					   &fault, &write_fault);

			if (fault || write_fault)

				goto fault;

			*pfn = hmm_device_entry_from_pfn(range,

					    swp_offset(entry));

			*pfn |= cpu_flags;

			*pfn |= range->flags[HMM_PFN_VALID];

			if (is_write_device_private_entry(entry))

				*pfn |= range->flags[HMM_PFN_WRITE];

			return 0;

		}

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