memremap: add an owner field to struct dev_pagemap

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.

Link: https://lore.kernel.org/r/20200316193216.920734-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Tested-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 79b1202b1c628e92acb6a0bb928926c73d18a13e..67fefb03b9b77c72488b7b05cda9c699bf9086ed 100644 (file)
--- 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 0ad5d87b5a8e57d6a093594476772ce8be3a6143..a4682272586e1c4e78d047c979f2906d3d93a70b 100644 (file)
--- 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 6fefb09af7c34ddc550debf429e6769e77c2cd40..60d97e8fd3c0d14e085ee1f9403d0121d636d0cc 100644 (file)
--- 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 09b5b7adc7731b22076238ebd00ff1653d6d7f44..9b2c97ceb775b24cd436cd9cbb8425b0fa3f4df7 100644 (file)
--- 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) ||