[PATCH 2/2] drm/i915/gvt: Initialize intel_gvt_gtt_entry in stack

[Tina Zhang]

In stack, intel_gvt_gtt_entry needs to be initialized before
being used, as the fields may have some garbage values.

W/o this patch, set_ggtt_entry prints:
-------------------------------------
274.046840: set_ggtt_entry: vgpu1:set ggtt entry 0x9bed8000ffffe900
274.046846: set_ggtt_entry: vgpu1:set ggtt entry 0xe55df001
274.046852: set_ggtt_entry: vgpu1:set ggtt entry 0x9bed8000ffffe900

0x9bed8000 is the stack grabage.

W/ this patch, set_ggtt_entry prints:
------------------------------------
274.046840: set_ggtt_entry: vgpu1:set ggtt entry 0xffffe900
274.046846: set_ggtt_entry: vgpu1:set ggtt entry 0xe55df001
274.046852: set_ggtt_entry: vgpu1:set ggtt entry 0xffffe900

Signed-off-by: Tina Zhang <tina.zhang at intel.com>
---
 drivers/gpu/drm/i915/gvt/gtt.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index dcc207f04b75..bcb649285707 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -2193,7 +2193,7 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
 	/* the VM may configure the whole GM space when ballooning is used */
 	if (!vgpu_gmadr_is_valid(vgpu, gma))
 		return 0;
-
+	e.val64 = 0;
 	e.type = GTT_TYPE_GGTT_PTE;
 	memcpy((void *)&e.val64 + (off & (info->gtt_entry_size - 1)), p_data,
 			bytes);
@@ -2246,7 +2246,8 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
 
 	if (!partial_update && (ops->test_present(&e))) {
 		gfn = ops->get_pfn(&e);
-		m = e;
+		m.val64 = e.val64;
+		m.type = e.type;
 
 		/* one PTE update may be issued in multiple writes and the
 		 * first write may not construct a valid gfn
@@ -2268,6 +2269,8 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
 		} else
 			ops->set_pfn(&m, dma_addr >> PAGE_SHIFT);
 	} else {
+		m.val64 = 0;
+		m.type = GTT_TYPE_GGTT_PTE;
 		ops->set_pfn(&m, gvt->gtt.scratch_mfn);
 		ops->clear_present(&m);
 	}
-- 
2.17.1