On 3/16/20 12:32 PM, Christoph Hellwig wrote:

Add a new opaque owner field to struct dev_pagemap, which will allow the hmm and migrate_vma code to identify who owns ZONE_DEVICE memory, and refuse to work on mappings not owned by the calling entity.

Signed-off-by: Christoph Hellwig hch@lst.de

This looks like a reasonable approach to take. Reviewed-by: Ralph Campbell rcampbell@nvidia.com

---

arch/powerpc/kvm/book3s_hv_uvmem.c | 2 ++ drivers/gpu/drm/nouveau/nouveau_dmem.c | 1 + include/linux/memremap.h | 4 ++++ mm/memremap.c | 4 ++++ 4 files changed, 11 insertions(+)

diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c index 79b1202b1c62..67fefb03b9b7 100644 --- a/arch/powerpc/kvm/book3s_hv_uvmem.c +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c @@ -779,6 +779,8 @@ int kvmppc_uvmem_init(void) kvmppc_uvmem_pgmap.type = MEMORY_DEVICE_PRIVATE; kvmppc_uvmem_pgmap.res = *res; kvmppc_uvmem_pgmap.ops = &kvmppc_uvmem_ops;

• /* just one global instance: */
• kvmppc_uvmem_pgmap.owner = &kvmppc_uvmem_pgmap; addr = memremap_pages(&kvmppc_uvmem_pgmap, NUMA_NO_NODE); if (IS_ERR(addr)) { ret = PTR_ERR(addr);

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c index 0ad5d87b5a8e..a4682272586e 100644 --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c @@ -526,6 +526,7 @@ nouveau_dmem_init(struct nouveau_drm *drm) drm->dmem->pagemap.type = MEMORY_DEVICE_PRIVATE; drm->dmem->pagemap.res = *res; drm->dmem->pagemap.ops = &nouveau_dmem_pagemap_ops;

• drm->dmem->pagemap.owner = drm->dev; if (IS_ERR(devm_memremap_pages(device, &drm->dmem->pagemap))) goto out_free;

diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 6fefb09af7c3..60d97e8fd3c0 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -103,6 +103,9 @@ struct dev_pagemap_ops {

• @type: memory type: see MEMORY_* in memory_hotplug.h
• @flags: PGMAP_* flags to specify defailed behavior
• @ops: method table

• • @owner: an opaque pointer identifying the entity that manages this
• • instance. Used by various helpers to make sure that no
• • foreign ZONE_DEVICE memory is accessed.
  */ struct dev_pagemap { struct vmem_altmap altmap;

@@ -113,6 +116,7 @@ struct dev_pagemap { enum memory_type type; unsigned int flags; const struct dev_pagemap_ops *ops;

• void *owner; };

  static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)

diff --git a/mm/memremap.c b/mm/memremap.c index 09b5b7adc773..9b2c97ceb775 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -181,6 +181,10 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) WARN(1, "Missing migrate_to_ram method\n"); return ERR_PTR(-EINVAL); }

• if (!pgmap->owner) {
  

• 	WARN(1, "Missing owner\n");
  

• 	return ERR_PTR(-EINVAL);
  

• }
  

  break; case MEMORY_DEVICE_FS_DAX: if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||