On 2022.12.20 17:40:14 +0800, Zheng Wang wrote:
> If intel_gvt_dma_map_guest_page failed, it will call
> ppgtt_invalidate_spt, which will finally free the spt. But the
> caller function ppgtt_populate_spt_by_guest_entry does not notice
> that, it will free spt again in its error path.
indent
>
> Fix this by undoing the mapping of DMA address and freeing sub_spt.
> Besides, leave the handle of spt destroy to caller function instead of
> callee function when error occurs.
>
> Fixes: b901b252b6cf ("drm/i915/gvt: Add 2M huge gtt support")
> Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx>
> ---
> v5:
> - remove unnecessary switch-case code for there is only one particular case,
> correct the unmap target from parent_spt to sub_spt.add more details in
> commit message. All suggested by Zhenyu
>
> v4:
> - fix by undo the mapping of DMA address and free sub_spt suggested by Zhi
>
> v3:
> - correct spelling mistake and remove unused variable suggested by Greg
>
> v2: https://lore.kernel.org/all/20221006165845.1735393-1-zyytlz.wz@xxxxxxx/
>
> v1: https://lore.kernel.org/all/20220928033340.1063949-1-zyytlz.wz@xxxxxxx/
> ---
> drivers/gpu/drm/i915/gvt/gtt.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> index 51e5e8fb505b..4d478a59eb7d 100644
> --- a/drivers/gpu/drm/i915/gvt/gtt.c
> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> @@ -1209,10 +1209,8 @@ static int split_2MB_gtt_entry(struct intel_vgpu *vgpu,
> for_each_shadow_entry(sub_spt, &sub_se, sub_index) {
> ret = intel_gvt_dma_map_guest_page(vgpu, start_gfn + sub_index,
> PAGE_SIZE, &dma_addr);
> - if (ret) {
> - ppgtt_invalidate_spt(spt);
> - return ret;
> - }
> + if (ret)
> + goto err;
> sub_se.val64 = se->val64;
>
> /* Copy the PAT field from PDE. */
> @@ -1231,6 +1229,18 @@ static int split_2MB_gtt_entry(struct intel_vgpu *vgpu,
> ops->set_pfn(se, sub_spt->shadow_page.mfn);
> ppgtt_set_shadow_entry(spt, se, index);
> return 0;
> +err:
> + /* Undone the existing mappings of DMA addr. */
We need a verb here for Undo.
> + for_each_present_shadow_entry(sub_spt, &sub_se, sub_index) {
> + gvt_vdbg_mm("invalidate 4K entry\n");
> + ppgtt_invalidate_pte(sub_spt, &sub_se);
> + }
> + /* Release the new allocated spt. */
> + trace_spt_change(sub_spt->vgpu->id, "release", sub_spt,
> + sub_spt->guest_page.gfn, sub_spt->shadow_page.type);
> + ppgtt_free_spt(sub_spt);
> + sub_spt = NULL;
Not need to reset local variable that has no use then.
I'll handle these trivial fixes during the merge.
Reviewed-by: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
thanks
> + return ret;
> }
>
> static int split_64KB_gtt_entry(struct intel_vgpu *vgpu,
> --
> 2.25.1
>
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