Re: [PATCH v8 7/7] iommu/riscv: Paging domain support

[Jason Gunthorpe <jgg@ziepe.ca>]

On Tue, Aug 06, 2024 at 12:24:40PM -0700, Easwar Hariharan wrote:
> On 6/14/2024 10:27 PM, Tomasz Jeznach wrote:
> > Introduce first-stage address translation support.
> > 
> > Page table configured by the IOMMU driver will use the highest mode
> > implemented by the hardware, unless not known at the domain allocation
> > time falling back to the CPU’s MMU page mode.
> > 
> > This change introduces IOTINVAL.VMA command, required to invalidate
> > any cached IOATC entries after mapping is updated and/or removed from
> > the paging domain.  Invalidations for the non-leaf page entries use
> > IOTINVAL for all addresses assigned to the protection domain for
> > hardware not supporting more granular non-leaf page table cache
> > invalidations.
> > 
> > Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
> > Reviewed-by: Zong Li <zong.li@sifive.com>
> > Signed-off-by: Tomasz Jeznach <tjeznach@rivosinc.com>
> > ---
> >  drivers/iommu/riscv/iommu.c | 642 +++++++++++++++++++++++++++++++++++-
> >  1 file changed, 639 insertions(+), 3 deletions(-)
> > 
> 
> > @@ -856,7 +1473,7 @@ static struct iommu_domain riscv_iommu_identity_domain = {
> >  
> >  static int riscv_iommu_device_domain_type(struct device *dev)
> >  {
> > -	return IOMMU_DOMAIN_IDENTITY;
> > +	return 0;
> >  }
> 
> <snip>
> Sorry for the drive by comment, I just happen to be in the nearby code
> context.
> 
> Nit: It may be better to use IOMMU_DOMAIN_BLOCKED here for readability
> rather than the bare value.

It is weird and confusing, but 0 means "I have nothing to add" not
BLOCKED.

You can't return BLOCKED from this op right now..

Jason