[PATCH V2 6/6] drm/i915/gvt: Check if get_next_pt_type() always returns a valid value

[Colin Xu]

On 2019-04-11 18:46, Aleksei Gimbitskii wrote:
> According to gtt_type_table[] function get_next_pt_type() may returns
> GTT_TYPE_INVALID in some cases. To prevent driver to try to create memory
> page with invalid data type, additional check is added.
>
> Signed-off-by: Aleksei Gimbitskii <aleksei.gimbitskii at intel.com>
> Cc: Zhenyu Wang <zhenyuw at linux.intel.com>
> Cc: Zhi Wang <zhi.a.wang at intel.com>
> Cc: Colin Xu <colin.xu at intel.com>
> ---
>   drivers/gpu/drm/i915/gvt/gtt.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> index 95cd8f25d6f9..c93e7a3a7f36 100644
> --- a/drivers/gpu/drm/i915/gvt/gtt.c
> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> @@ -1079,6 +1079,9 @@ static struct intel_vgpu_ppgtt_spt *ppgtt_populate_spt_by_guest_entry(
>   	} else {
>   		int type = get_next_pt_type(we->type);
>   
> +		if (!gtt_type_is_pt(type))
> +			goto err;
> +

Logically it's OK since it guarantees valid spt->shadow_page.type or spt->guest_page.type.

I'm still not sure which way to change is better, see comments in [patch v2 1/6].
Looking forward comments from others.

>   		spt = ppgtt_alloc_spt_gfn(vgpu, type, ops->get_pfn(we), ips);
>   		if (IS_ERR(spt)) {
>   			ret = PTR_ERR(spt);

-- 
Best Regards,
Colin Xu