linux-kernel - [PATCH] nouveau/svm: Fix to migrate all requested pages

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Date:   Wed, 20 Jul 2022 16:27:45 +1000
From:   Alistair Popple <apopple@...dia.com>
To:     bskeggs@...hat.com, rcampbell@...dia.com
Cc:     kherbst@...hat.com, lyude@...hat.com, airlied@...ux.ie,
        daniel@...ll.ch, nouveau@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        jhubbard@...dia.com, Alistair Popple <apopple@...dia.com>
Subject: [PATCH] nouveau/svm: Fix to migrate all requested pages

Users may request that pages from an OpenCL SVM allocation be migrated
to the GPU with clEnqueueSVMMigrateMem(). In Nouveau this will call into
nouveau_dmem_migrate_vma() to do the migration. If the total range to be
migrated exceeds SG_MAX_SINGLE_ALLOC the pages will be migrated in
chunks of size SG_MAX_SINGLE_ALLOC. However a typo in updating the
starting address means that only the first chunk will get migrated.

Fix the calculation so that the entire range will get migrated if
possible.

Signed-off-by: Alistair Popple <apopple@...dia.com>
Fixes: e3d8b0890469 ("drm/nouveau/svm: map pages after migration")
---
 drivers/gpu/drm/nouveau/nouveau_dmem.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 7ba66ad68a8a..16356611b5b9 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -680,7 +680,11 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
 		goto out_free_dma;
 
 	for (i = 0; i < npages; i += max) {
-		args.end = start + (max << PAGE_SHIFT);
+		if (args.start + (max << PAGE_SHIFT) > end)
+			args.end = end;
+		else
+			args.end = args.start + (max << PAGE_SHIFT);
+
 		ret = migrate_vma_setup(&args);
 		if (ret)
 			goto out_free_pfns;
-- 
2.35.1