[PATCH 2/4] drm/i915/gvt: Warning for invalid ggtt access

[Xiong Zhang]

Instead of silently return virtual ggtt entries that guest is allowed
to access, this patch add extra range check. If guest read out of
range, it will print a warning and return 0. If guest write out
of range, the write will be dropped without any message.

Signed-off-by: Xiong Zhang <xiong.y.zhang at intel.com>
---
 drivers/gpu/drm/i915/gvt/gtt.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index d767c45..68062ee 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -2131,11 +2131,20 @@ static int emulate_ggtt_mmio_read(struct intel_vgpu *vgpu,
 	struct intel_vgpu_mm *ggtt_mm = vgpu->gtt.ggtt_mm;
 	const struct intel_gvt_device_info *info = &vgpu->gvt->device_info;
 	unsigned long index = off >> info->gtt_entry_size_shift;
+	unsigned long gma;
 	struct intel_gvt_gtt_entry e;
 
 	if (bytes != 4 && bytes != 8)
 		return -EINVAL;
 
+	gma = index << I915_GTT_PAGE_SHIFT;
+	if (!intel_gvt_ggtt_validate_range(vgpu,
+					   gma, 1 << I915_GTT_PAGE_SHIFT)) {
+		gvt_dbg_mm("read invalid ggtt at 0x%lx\n", gma);
+		memset(p_data, 0, bytes);
+		return 0;
+	}
+
 	ggtt_get_guest_entry(ggtt_mm, &e, index);
 	memcpy(p_data, (void *)&e.val64 + (off & (info->gtt_entry_size - 1)),
 			bytes);
-- 
2.7.4