Re: [Qemu-devel] [PATCH v3 00/12] Introduce new iommu notifier framework for virt-SVA

[Peter Xu]

On Thu, Mar 01, 2018 at 06:33:23PM +0800, Liu, Yi L wrote:
> This patchset is to introduce a notifier framework for virt-SVA.
> You may find virt-SVA design details from the link below.
> 
> https://lists.gnu.org/archive/html/qemu-devel/2017-04/msg04925.html
> 
> SVA is short for Shared Virtual Addressing. This is also called Shared
> Virtual Memory in previous patchsets. However, SVM is confusing as it
> can also be short for Secure Virtual Machine. So this patchset use
> Shared Virtual Addressing instead of Shared Virtual Memory. And it
> would be applied in future (SVA)related patch series as well.
> 
> Qemu has an existing notifier framework based on MemoryRegion, which
> are used for MAP/UNMAP. However, it is not well suited for virt-SVA.
> Reasons are as below:
> - virt-SVA works along with PT = 1
> - if PT = 1 IOMMU MR are disabled so MR notifier are not registered
> - new notifiers do not fit nicely in this framework as they need to be
>   registered even if PT = 1
> - need a new framework to attach the new notifiers
> - Additional background can be got from:
>   https://lists.gnu.org/archive/html/qemu-devel/2017-04/msg04931.html
> 
> So a new iommu notifier framework is needed. This patchset introduces
> a notifier framework based on IOMMUSVAContext. IOMMUSVAContext is
> introduced to be an abstract of virt-SVA operations in Qemu.
> 
> Patch Overview:
> * 1 - 2: rename existing naming, the IOMMU MemoryRegion Notifier
>          framework
> * 3 - 4: introduce SVA notifier framework based on IOMMUSVAContext
> * 5 - 7: introduce PCISVAOps and expose the SVA notfier framework
>          through hw/pci layer
> * 8 - 12: show the usage of SVA notifier in Intel vIOMMU emulator

Do you have online branch so that I can check out?

The patches are a bit scattered and it's really hard for me to
reference things within it... So a complete tree to read would be
nice.

I roughly went over most of the patches, and the framework you
introduced is still not that clear to me.  For now I feel like it can
be simplified somehow, but I'll hold and speak after I read the whole
tree again.

Also, it'll be good too if you can always provide some status update
of the kernel-counterpart it.

Thanks,

-- 
Peter Xu