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

Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> · Wed, 25 Sep 2019 10:48:32 +0800

Hi Kevin,

On 9/24/19 3:00 PM, Tian, Kevin wrote:
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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