Re: [PATCH v3 00/10] Add Intel VT-d nested translation

[Jason Gunthorpe]

On Mon, May 29, 2023 at 06:16:44PM -0600, Alex Williamson wrote:
> On Mon, 29 May 2023 15:43:02 -0300
> Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
> 
> > On Wed, May 24, 2023 at 08:59:43AM +0000, Tian, Kevin wrote:
> > 
> > > At least this looks a reasonable tradeoff to some proprietary VMMs
> > > which never adds RO mappings in stage-2 today.  
> > 
> > What is the reason for the RO anyhow?
> > 
> > Would it be so bad if it was DMA mapped as RW due to the errata?
> 
> What if it's the zero page?  Thanks,

GUP doesn't return the zero page if FOL_WRITE is specified

Jason