[PATCH 52/55] drivers: hv: dxgkrnl: Use pin_user_pages instead of get_user_pages for DMA accessible memory

[Eric Curtin <ericcurtin17@gmail.com>]

From: Iouri Tarassov <iourit@linux.microsoft.com>

Pages, which are obtained by calling get_user_pages(), can be evicted from memory.
pin_user_pages() should be used for memory, which is accessed by DMA.

Signed-off-by: Iouri Tarassov <iourit@linux.microsoft.com>
---
 drivers/hv/dxgkrnl/dxgadapter.c |  2 +-
 drivers/hv/dxgkrnl/dxgvmbus.c   | 12 ++++++++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/hv/dxgkrnl/dxgadapter.c b/drivers/hv/dxgkrnl/dxgadapter.c
index cf946e476411..c94283b09fa1 100644
--- a/drivers/hv/dxgkrnl/dxgadapter.c
+++ b/drivers/hv/dxgkrnl/dxgadapter.c
@@ -882,7 +882,7 @@ struct dxgallocation *dxgallocation_create(struct dxgprocess *process)
 void dxgallocation_stop(struct dxgallocation *alloc)
 {
 	if (alloc->pages) {
-		release_pages(alloc->pages, alloc->num_pages);
+		unpin_user_pages(alloc->pages, alloc->num_pages);
 		vfree(alloc->pages);
 		alloc->pages = NULL;
 	}
diff --git a/drivers/hv/dxgkrnl/dxgvmbus.c b/drivers/hv/dxgkrnl/dxgvmbus.c
index 467e7707c8c7..abb6d2af89ac 100644
--- a/drivers/hv/dxgkrnl/dxgvmbus.c
+++ b/drivers/hv/dxgkrnl/dxgvmbus.c
@@ -1457,6 +1457,7 @@ int create_existing_sysmem(struct dxgdevice *device,
 	u64 *pfn;
 	u32 pages_to_send;
 	u32 i;
+	u32 gup_flags = FOLL_LONGTERM;
 	struct dxgglobal *dxgglobal = dxggbl();
 
 	/*
@@ -1475,12 +1476,15 @@ int create_existing_sysmem(struct dxgdevice *device,
 		ret = -ENOMEM;
 		goto cleanup;
 	}
-	ret1 = get_user_pages_fast((unsigned long)sysmem, npages, !read_only,
-				  dxgalloc->pages);
+	if (!read_only)
+		gup_flags |= FOLL_WRITE;
+	ret1 = pin_user_pages_fast((unsigned long)sysmem, npages, gup_flags,
+				   dxgalloc->pages);
 	if (ret1 != npages) {
 		DXG_ERR("get_user_pages_fast failed: %d", ret1);
-		if (ret1 > 0 && ret1 < npages)
-			release_pages(dxgalloc->pages, ret1);
+		if (ret1 > 0 && ret1 < npages) {
+			unpin_user_pages(dxgalloc->pages, ret1);
+		}
 		vfree(dxgalloc->pages);
 		dxgalloc->pages = NULL;
 		ret = -ENOMEM;