Hi Julien, > On 21 Oct 2021, at 14:47, Julien Grall <jul...@xen.org> wrote: > > > > On 21/10/2021 14:15, Bertrand Marquis wrote: >> Hi Julien, > > Hi Bertand, > >>> On 21 Oct 2021, at 10:28, Julien Grall <jul...@xen.org> wrote: >>> >>> Hi all, >>> >>> While going through the passthrough code. I noticed that we don't have a >>> common lock for the IOMMU between the PCI and DT code. >>> >>> This is going to be an issue given it would technically be possible to add >>> a PCI device while assigning a DT. >>> >>> Rahul, Bertrand, Oleksandr, can you have a look at the issue? >> Yes we can have a look at this. >> Right now pci device add is done by dom0 so I do not think we have an issue >> in practice unless I wrongly understood something > This will depend on the XSM policy. With the default one, then yes I agree > that only dom0 (we don't support hardware domain) can add PCI device. > > However, this restriction doesn't really matter here. You would be relying on > dom0 to do the locking and AFAIK this doesn't exist. Instead, the admin would > have to ensure that two don't happen at the same time. > > Anyway, I think Xen should take care of preventing concurrent IOMMU > operations rather than relying on external subsystem (e.g. dom0) to do it. At > least the Arm SMMU driver will rely the generic locking to modify atomically > internal list.
Agree, was just trying to make sure I understood the problem correctly. We will check that. Cheers Bertrand > > Cheers, > > -- > Julien Grall
