[PATCH 4.8 25/96] drm/nouveau/bios: require checksum to match for fast acpi shadow method

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Skeggs <bskeggs@xxxxxxxxxx>

commit 5dc7f4aa9d84ea94b54a9bfcef095f0289f1ebda upstream.

Signed-off-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/nouveau/nvkm/subdev/bios/priv.h       |    1 +
 drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadow.c     |    7 +++++--
 drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowacpi.c |    1 +
 3 files changed, 7 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/priv.h
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/priv.h
@@ -12,6 +12,7 @@ struct nvbios_source {
 	bool rw;
 	bool ignore_checksum;
 	bool no_pcir;
+	bool require_checksum;
 };
 
 int nvbios_extend(struct nvkm_bios *, u32 length);
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadow.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadow.c
@@ -86,9 +86,12 @@ shadow_image(struct nvkm_bios *bios, int
 		    nvbios_checksum(&bios->data[image.base], image.size)) {
 			nvkm_debug(subdev, "%08x: checksum failed\n",
 				   image.base);
-			if (mthd->func->rw)
+			if (!mthd->func->require_checksum) {
+				if (mthd->func->rw)
+					score += 1;
 				score += 1;
-			score += 1;
+			} else
+				return 0;
 		} else {
 			score += 3;
 		}
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowacpi.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowacpi.c
@@ -99,6 +99,7 @@ nvbios_acpi_fast = {
 	.init = acpi_init,
 	.read = acpi_read_fast,
 	.rw = false,
+	.require_checksum = true,
 };
 
 const struct nvbios_source