Re: [PATCH v7 9/9] vfio/type1: Handle different mdev isolation type

[Lu Baolu]

Hi Neo,

On 3/9/19 2:03 AM, Neo Jia wrote:
> On Thu, Mar 07, 2019 at 04:56:23PM -0700, Alex Williamson wrote:
> > On Thu, 7 Mar 2019 00:44:54 -0800
> > Neo Jia <cjia@xxxxxxxxxx> wrote:
> >
> > > On Fri, Feb 22, 2019 at 10:19:27AM +0800, Lu Baolu wrote:
> > > > This adds the support to determine the isolation type
> > > > of a mediated device group by checking whether it has
> > > > an iommu device. If an iommu device exists, an iommu
> > > > domain will be allocated and then attached to the iommu
> > > > device. Otherwise, keep the same behavior as it is.
> > > >
> > > > Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
> > > > Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > > > Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> > > > Signed-off-by: Sanjay Kumar <sanjay.k.kumar@xxxxxxxxx>
> > > > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
> > > > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > > > Reviewed-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
> > > > ---
> > > >   drivers/vfio/vfio_iommu_type1.c | 48 ++++++++++++++++++++++++++++-----
> > > >   1 file changed, 41 insertions(+), 7 deletions(-)
> > > >
> > > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> > > > index ccc4165474aa..f1392c582a3c 100644
> > > > --- a/drivers/vfio/vfio_iommu_type1.c
> > > > +++ b/drivers/vfio/vfio_iommu_type1.c
> > > > @@ -1368,13 +1368,40 @@ static void vfio_iommu_detach_group(struct vfio_domain *domain,
> > > >   		iommu_detach_group(domain->domain, group->iommu_group);
> > > >   }
> > > >     
> > >
> > > Hi Baolu,
> > >
> > > To allow IOMMU-awared mdev, I think you need to modify the
> > > vfio_iommu_type1_pin_pages and vfio_iommu_type1_unpin_pages to remove the
> > > iommu->external_domain check.
> > >
> > > Could you please include that in your patch? If not, I can send out a separate
> > > patch to address that issue.
> >
> > I figured it was intentional that an IOMMU backed mdev would not use
> > the pin/unpin interface and therefore the exiting -EINVAL returns would
> > be correct.  Can you elaborate on the use case for still requiring the
> > mdev pin/unpin interface for these devices?  Thanks,
>
> Sure. We are using this api to fetch a pfn of a guest physical address so we can
> access it for PV.

Okay, I will remove these two checks in the next version.

Best regards,
Lu Baolu