Linux Virtualization - Mar 2023 - [PATCH v2] vhost/vdpa: Add MSI translation tables to iommu for software-managed MSI

On Mon, Feb 20, 2023 at 10:37:18AM +0800, Jason Wang
wrote:
> On Fri, Feb 17, 2023 at 8:43 PM Jason Gunthorpe <jgg at nvidia.com>
wrote:
> >
> > On Fri, Feb 17, 2023 at 05:12:29AM -0500, Michael S. Tsirkin wrote:
> > > On Thu, Feb 16, 2023 at 08:14:50PM -0400, Jason Gunthorpe wrote:
> > > > On Tue, Feb 07, 2023 at 08:08:43PM +0800, Nanyong Sun wrote:
> > > > > From: Rong Wang <wangrong68 at huawei.com>
> > > > >
> > > > > Once enable iommu domain for one device, the MSI
> > > > > translation tables have to be there for
software-managed MSI.
> > > > > Otherwise, platform with software-managed MSI without
an
> > > > > irq bypass function, can not get a correct memory write
event
> > > > > from pcie, will not get irqs.
> > > > > The solution is to obtain the MSI phy base address from
> > > > > iommu reserved region, and set it to iommu MSI cookie,
> > > > > then translation tables will be created while request
irq.
> > > >
> > > > Probably not what anyone wants to hear, but I would prefer
we not add
> > > > more uses of this stuff. It looks like we have to get rid of
> > > > iommu_get_msi_cookie() :\
> > > >
> > > > I'd like it if vdpa could move to iommufd not keep
copying stuff from
> > > > it..
> > >
> > > Absolutely but when is that happening?
> >
> > Don't know, I think it has to come from the VDPA maintainers,
Nicolin
> > made some drafts but wasn't able to get it beyond that.
> 
> Cindy (cced) will carry on the work.
> 
> Thanks
Hmm didn't see anything yet. Nanyong Sun maybe you can take a look?
> >
> > Please have people who need more iommu platform enablement to pick it
> > up instead of merging hacks like this..
> >
> > We are very close to having nested translation on ARM so anyone who is
> > serious about VDPA on ARM is going to need iommufd anyhow.
> >
> > Jason
> >

On Fri, Mar 10, 2023 at 4:41?PM Michael S. Tsirkin <mst at redhat.com>
wrote:
>
> On Mon, Feb 20, 2023 at 10:37:18AM +0800, Jason Wang wrote:
> > On Fri, Feb 17, 2023 at 8:43 PM Jason Gunthorpe <jgg at
nvidia.com> wrote:
> > >
> > > On Fri, Feb 17, 2023 at 05:12:29AM -0500, Michael S. Tsirkin
wrote:
> > > > On Thu, Feb 16, 2023 at 08:14:50PM -0400, Jason Gunthorpe
wrote:
> > > > > On Tue, Feb 07, 2023 at 08:08:43PM +0800, Nanyong Sun
wrote:
> > > > > > From: Rong Wang <wangrong68 at huawei.com>
> > > > > >
> > > > > > Once enable iommu domain for one device, the MSI
> > > > > > translation tables have to be there for
software-managed MSI.
> > > > > > Otherwise, platform with software-managed MSI
without an
> > > > > > irq bypass function, can not get a correct memory
write event
> > > > > > from pcie, will not get irqs.
> > > > > > The solution is to obtain the MSI phy base address
from
> > > > > > iommu reserved region, and set it to iommu MSI
cookie,
> > > > > > then translation tables will be created while
request irq.
> > > > >
> > > > > Probably not what anyone wants to hear, but I would
prefer we not add
> > > > > more uses of this stuff. It looks like we have to get
rid of
> > > > > iommu_get_msi_cookie() :\
> > > > >
> > > > > I'd like it if vdpa could move to iommufd not keep
copying stuff from
> > > > > it..
> > > >
> > > > Absolutely but when is that happening?
> > >
> > > Don't know, I think it has to come from the VDPA maintainers,
Nicolin
> > > made some drafts but wasn't able to get it beyond that.
> >
> > Cindy (cced) will carry on the work.
> >
> > Thanks
>
> Hmm didn't see anything yet. Nanyong Sun maybe you can take a look?
Just to clarify, Cindy will work on the iommufd conversion for
vhost-vDPA, the changes are non-trivial and may take time. Before we
are able to achieve that,  I think we still need something like this
patch to make vDPA work on software managed MSI platforms.

Maybe Nanyong can post a new version that addresses the comment so far?

Thanks
>
> > >
> > > Please have people who need more iommu platform enablement to
pick it
> > > up instead of merging hacks like this..
> > >
> > > We are very close to having nested translation on ARM so anyone
who is
> > > serious about VDPA on ARM is going to need iommufd anyhow.
> > >
> > > Jason
> > >
>