[PATCH] drm/i915/gvt: set shadow entry to scratch page while p2m failed

[Zhenyu Wang]

On 2017.03.20 18:03:32 +0800, Xiaoguang Chen wrote:
> Sometimes guest driver will only update partial of the GGTT entry then
> access it. In this situation a failure will happen while translating
> the gpa to hpa.
> Now in this situation we let the corresponding shadow entry pointing
> to a scratch page.
> 
> Signed-off-by: Zhi Wang <zhi.a.wang at intel.com>
> Signed-off-by: Xiaoguang Chen <xiaoguang.chen at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/gtt.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> index da73127..96aa30c 100644
> --- a/drivers/gpu/drm/i915/gvt/gtt.c
> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> @@ -1837,11 +1837,17 @@ static int emulate_gtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
>  		ret = gtt_entry_p2m(vgpu, &e, &m);
>  		if (ret) {
>  			gvt_vgpu_err("fail to translate guest gtt entry\n");
> -			return ret;
> +			/* guest driver may read/write the entry when partial
> +			 * update the entry in this situation p2m will fail
> +			 * settting the shadow entry to point to a scratch page
> +			 */
> +			ops->set_pfn(&m,
> +			vgpu->gtt.scratch_pt[GTT_TYPE_GGTT_PTE].page_mfn);
>  		}

Have you seen Ping's comment to use GTT_TYPE_PPGTT_PTE_PT, otherwise this
scratch page num seems invalid. Hmm, why we don't have scratch for GGTT?

>  	} else {
>  		m = e;
> -		m.val64 = 0;
> +		ops->set_pfn(&m,
> +		vgpu->gtt.scratch_pt[GTT_TYPE_GGTT_PTE].page_mfn);
>  	}
>  
>  	ggtt_set_shadow_entry(ggtt_mm, &m, g_gtt_index);
> -- 
> 2.7.4
> 
> _______________________________________________
> intel-gvt-dev mailing list
> intel-gvt-dev at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gvt-dev

-- 
Open Source Technology Center, Intel ltd.

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