Re: [RFC PATCH 0/4] Use 1st-level for DMA remapping in guest

[Lu Baolu]

Hi Kevin,

On 9/24/19 3:00 PM, Tian, Kevin wrote:
> > > >       '-----------'
> > > >       '-----------'
> > > >
> > > > This patch series only aims to achieve the first goal, a.k.a using
> first goal? then what are other goals? I didn't spot such information.

The overall goal is to use IOMMU nested mode to avoid shadow page table
and VMEXIT when map an gIOVA. This includes below 4 steps (maybe not
accurate, but you could get the point.)

1) GIOVA mappings over 1st-level page table;
2) binding vIOMMU 1st level page table to the pIOMMU;
3) using pIOMMU second level for GPA->HPA translation;
4) enable nested (a.k.a. dual stage) translation in host.

This patch set aims to achieve 1).

> Also earlier you mentioned the new approach (nested) is more secure
> than shadowing. why?

My bad! After reconsideration, I realized that it's not "more secure".

Thanks for pointing this out.

Best regards,
Baolu