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drm/i915/gvt: Fix kernel oops for 3-level ppgtt guest 

As i915 won't allocate extra PDP for current default PML4 table,
so for 3-level ppgtt guest, we would hit kernel pointer access
failure on extra PDP pointers. So this trys to bypass that now.
It won't impact real shadow PPGTT setup, so guest context still
works.

This is verified on 4.15 guest kernel with i915.enable_ppgtt=1
to force on old aliasing ppgtt behavior.

Fixes: 4f15665ccb ("drm/i915: Add ppgtt to GVT GEM context")
Reviewed-by: Xiong Zhang <xiong.y.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200506095918.124913-1-zhenyuw@linux.intel.com
This commit is contained in:
Zhenyu Wang 2020-05-06 17:59:18 +08:00
parent f965b68188
commit 72a7a9925e
1 changed files with 5 additions and 1 deletions
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6
drivers/gpu/drm/i915/gvt/scheduler.c
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@ -379,7 +379,11 @@ static void set_context_ppgtt_from_shadow(struct intel_vgpu_workload *workload,
for (i = 0; i < GVT_RING_CTX_NR_PDPS; i++) {
struct i915_page_directory * const pd =
i915_pd_entry(ppgtt->pd, i);
/* skip now as current i915 ppgtt alloc won't allocate
top level pdp for non 4-level table, won't impact
shadow ppgtt. */
if (!pd)
break;
px_dma(pd) = mm->ppgtt_mm.shadow_pdps[i];
}
}