> -----Original Message----- > From: Jason Gunthorpe [mailto:j...@nvidia.com] > Sent: 16 May 2023 13:00 > To: Shameerali Kolothum Thodi <shameerali.kolothum.th...@huawei.com> > Cc: Avihai Horon <avih...@nvidia.com>; qemu-devel@nongnu.org; Alex > Williamson <alex.william...@redhat.com>; Juan Quintela > <quint...@redhat.com>; Dr. David Alan Gilbert <dgilb...@redhat.com>; > Michael S. Tsirkin <m...@redhat.com>; Cornelia Huck <coh...@redhat.com>; > Paolo Bonzini <pbonz...@redhat.com>; Vladimir Sementsov-Ogievskiy > <vsement...@yandex-team.ru>; Cédric Le Goater <c...@redhat.com>; Yishai > Hadas <yish...@nvidia.com>; Maor Gottlieb <ma...@nvidia.com>; Kirti > Wankhede <kwankh...@nvidia.com>; Tarun Gupta <targu...@nvidia.com>; > Joao Martins <joao.m.mart...@oracle.com> > Subject: Re: [PATCH v11 05/11] vfio/migration: Block multiple devices > migration > > On Tue, May 16, 2023 at 10:03:54AM +0000, Shameerali Kolothum Thodi > wrote: > > > > Currently VFIO migration doesn't implement some kind of intermediate > > > quiescent state in which P2P DMAs are quiesced before stopping or > > > running the device. This can cause problems in multi-device migration > > > where the devices are doing P2P DMAs, since the devices are not stopped > > > together at the same time. > > > > > > Until such support is added, block migration of multiple devices. > > > > Missed this one. Currently this blocks even if the attached devices are not > > capable of P2P DMAs. eg; HiSilicon ACC devices. These are integrated end > point > > devices without any P2P capability between them. Is it Ok to check for > > VFIO_MIGRATION_P2P flag and allow if the devices are not supporting > that? > > Lacking VFIO_MIGRATION_P2P doesn't mean the device is incapable of > P2P, it means the migration can't support P2P. > > We'd need some kind of new flag to check and such devices should be > blocked from creating P2P mappings. Basically we don't currently > fully support devices that are incapable of P2P operations. Ok. I will take a look. > What happens on your platform if a guest tries to do P2P? Does the > platform crash? I am not sure. Since the devices are behind SMMU, I was under the assumption that we do have the guarantee of isolation here(grouping). Or this is something we are worried only during migration? Thanks, Shameer
RE: [PATCH v11 05/11] vfio/migration: Block multiple devices migration
Shameerali Kolothum Thodi via Tue, 16 May 2023 06:57:52 -0700
- RE: [PATCH v11 05/11] vfio/migration: Block ... Shameerali Kolothum Thodi via
- Re: [PATCH v11 05/11] vfio/migration: B... Jason Gunthorpe
- RE: [PATCH v11 05/11] vfio/migratio... Shameerali Kolothum Thodi via
- Re: [PATCH v11 05/11] vfio/migr... Jason Gunthorpe
- Re: [PATCH v11 05/11] vfio/migr... Alex Williamson
- RE: [PATCH v11 05/11] vfio/... Shameerali Kolothum Thodi via
- Re: [PATCH v11 05/11] ... Jason Gunthorpe