mm/hmm: check the device private page owner in hmm_range_fault()

hmm_range_fault() will succeed for any kind of device private memory, even
if it doesn't belong to the calling entity.  While nouveau has some crude
checks for that, they are broken because they assume nouveau is the only
user of device private memory.  Fix this by passing in an expected pgmap
owner in the hmm_range_fault structure.

If a device_private page is found and doesn't match the owner then it is
treated as an non-present and non-faultable page.

This prevents a bug in amdgpu, where it doesn't know how to handle
device_private pages, but hmm_range_fault would return them anyhow.

Fixes: 4ef589dc9b10 ("mm/hmm/devmem: device memory hotplug using ZONE_DEVICE")
Link: https://lore.kernel.org/r/20200316193216.920734-5-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 0 insertions, 12 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index edfd0805fba4..ad89e09a0be3 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -672,12 +672,6 @@ out:
 	return ret;
 }
 
-static inline bool
-nouveau_dmem_page(struct nouveau_drm *drm, struct page *page)
-{
-	return is_device_private_page(page) && drm->dmem == page_to_dmem(page);
-}
-
 void
 nouveau_dmem_convert_pfn(struct nouveau_drm *drm,
 			 struct hmm_range *range)
@@ -696,12 +690,6 @@ nouveau_dmem_convert_pfn(struct nouveau_drm *drm,
 		if (!is_device_private_page(page))
 			continue;
 
-		if (!nouveau_dmem_page(drm, page)) {
-			WARN(1, "Some unknown device memory !\n");
-			range->pfns[i] = 0;
-			continue;
-		}
-
 		addr = nouveau_dmem_page_addr(page);
 		range->pfns[i] &= ((1UL << range->pfn_shift) - 1);
 		range->pfns[i] |= (addr >> PAGE_SHIFT) << range->pfn_shift;