Re: [Intel-gfx] [PATCH v3 03/28] drm/i915/gvt: Verify hugepages are contiguous in physical address space

Sean Christopherson
2023-05-17T14:50:30Z

On Tue, May 16, 2023, Yan Zhao wrote:
> hi Sean
>
> Do you think it's necessary to double check that struct page pointers
> are also contiguous?

No, the virtual address space should be irrelevant. The only way it would be
problematic is if something in dma_map_page() expected to be able to access the
entire chunk of memory by getting the virtual address of only the first page,
but I can't imagine that code is reading or writing memory, let alone doing so
across a huge range of memory.

> And do you like to also include a fix as below, which is to remove the
> warning in vfio_device_container_unpin_pages() when npage is 0?
>
> @ -169,7 +173,8 @@ static int gvt_pin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
> *page = base_page;
> return 0;
> err:
> - gvt_unpin_guest_page(vgpu, gfn, npage * PAGE_SIZE);
> + if (npage)
> + gvt_unpin_guest_page(vgpu, gfn, npage * PAGE_SIZE);
> return ret;
> }

Sure. Want to give your SoB? I'll write a changelog.

Thanks again!