Re: [RFC v2 1/1] memory: Delete assertion in memory_region_unregister_iommu_notifier

[Peter Xu]

On Tue, Jun 30, 2020 at 05:23:31PM +0800, Jason Wang wrote:
> > > Ok, we had a dedicated mr for interrupt:
> > > 
> > > memory_region_add_subregion_overlap(MEMORY_REGION(&vtd_dev_as->iommu),
> > > VTD_INTERRUPT_ADDR_FIRST,
> > > &vtd_dev_as->iommu_ir, 1);
> > > 
> > > So it should be fine. I guess the reason that I'm asking is that I thought
> > > "IR" means "Interrupt remapping" but in fact it means "Interrupt Region"?

I was meaning "interrupt remapping", and of course it's the interrupt region
too when IR enabled...

> > > 
> > > But I'm still not clear about the invalidation part for interrupt region,
> > > maybe you can elaborate a little more on this.
> > > 
> > > Btw, I think guest can trigger the assert in vtd_do_iommu_translate() if 
> > > we
> > > teach vhost to DMA to that region:
> > 
> > Why would we want to?
> 
> 
> I meant a buggy(malicious) guest driver.

Yes seems possible.  Do you want to post a patch?  Let me know if you want me
to...  Thanks,

-- 
Peter Xu