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Thu, 19 Mar 2026 10:24:24 -0700 (PDT) MIME-Version: 1.0 References: <20260129212510.967611-1-dmatlack@google.com> <20260129212510.967611-11-dmatlack@google.com> <20260226170030.5a938c74@shazbot.org> <20260227084658.3767d801@shazbot.org> <20260227105720.522ca97f@shazbot.org> <20260313083918.00005731@linux.microsoft.com> <20260319093932.000078c2@linux.microsoft.com> In-Reply-To: <20260319093932.000078c2@linux.microsoft.com> From: David Matlack Date: Thu, 19 Mar 2026 10:23:56 -0700 X-Gm-Features: AaiRm53rqLDO8igOEPnPEHv7Le9OPlkg99gzLBiOllDBuZj0inzOHo1IukO9vNo Message-ID: Subject: Re: [PATCH v2 10/22] vfio/pci: Skip reset of preserved device after Live Update To: Jacob Pan Cc: Alex Williamson , Adithya Jayachandran , Alexander Graf , Alex Mastro , Alistair Popple , Andrew Morton , Ankit Agrawal , Bjorn Helgaas , Chris Li , David Rientjes , Jason Gunthorpe , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Kevin Tian , kexec@lists.infradead.org, kvm@vger.kernel.org, Leon Romanovsky , Leon Romanovsky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Lukas Wunner , =?UTF-8?Q?Micha=C5=82_Winiarski?= , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Raghavendra Rao Ananta , Rodrigo Vivi , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , Tomita Moeko , Vipin Sharma , Vivek Kasireddy , William Tu , Yi Liu , Zhu Yanjun Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 2D977A0013 X-Rspamd-Server: rspam08 X-Stat-Signature: 8c5bi5cwous75cu59ca7kpmp5zgar3rx X-HE-Tag: 1773941066-278241 X-HE-Meta: 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 19, 2026 at 9:39=E2=80=AFAM Jacob Pan wrote: > > Hi David, > > On Mon, 16 Mar 2026 11:11:20 -0700 > David Matlack wrote: > > > On Fri, Mar 13, 2026 at 8:39=E2=80=AFAM Jacob Pan > > wrote: > > > On Thu, 12 Mar 2026 23:39:45 +0000 > > > David Matlack wrote: > > > > > > +config VFIO_PCI_LIVEUPDATE > > > > + bool "VFIO PCI support for Live Update (EXPERIMENTAL)" > > > > + depends on LIVEUPDATE && VFIO_PCI > > > > + help > > > > + Support for preserving devices bound to vfio-pci across > > > > a Live > > > > + Update. The eventual goal is that preserved devices can > > > > run > > > > + uninterrupted during a Live Update, including DMA to > > > > preserved > > > > + memory buffers and P2P. However there are many steps > > > > still needed to > > > > + achieve this, including: > > > > + > > > > + - Preservation of iommufd files > > > > + - Preservation of IOMMU driver state > > > In the interim, what do you think about moving forward with noiommu > > > mode without preserving IOMMU driver state? > > > > I haven't gotten a chance to look at your noiommu patches yet, but I > > do think noiommu will probably be a good way to develop the VFIO and > > PCI support for Live Update without blocking on IOMMU driver support. > > > > > I=E2=80=99ve tested your > > > vfio_pci_liveupdate_kexec_test with the noiommu cdev, and it works > > > as expected. > > > > Would you be able to send patches to add noiommu support to VFIO > > selftests? That would be very helpful toward allowing us to develop > > and test Live Update support with noiommu. > > It is included in the noiommu patchset; the only difference is that the > VFIO cdev name is prefixed with noiommu, which is not strictly required > and is done out of caution. > > /dev/vfio/ > |-- devices > | `-- noiommu-vfio0 > > https://lore.kernel.org/linux-iommu/20260312155637.376854-10-jacob.pan@li= nux.microsoft.com/ This one flew under my radar. I will take a look and respond there, thanks!