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: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index dee446278417c01653ff6fb8a981ba9835a6d7c3..90821ce5e6cad077b5af2e8a7ca9b7f2345abca0 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -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] = {

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 0e36345d395c5c26a775648b10627fe190b2ef39..edfd0805fba4a46cbbf547b7f519637e9814be66 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -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;
        }
 }

diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index df9bf1fd1bc0be7180d18d85d246d1156e5d9bab..39c731a99937c65dd8d2e6a0640beffc42e7b2fc 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -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

diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 4bf8d6997b12d3fa9a2fa858c4a4c57116142acb..5e6034f105c3ee70dd9153e58064b5797ddd7b58 100644 (file)
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -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
 };
 

diff --git a/mm/hmm.c b/mm/hmm.c
index a5f4f80109656901003daceed0ad89fd23b82535..613b34950c305f04cd66e1deaf516c3d93f7ee76 100644 (file)
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -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;
                }