From: Jason Gunthorpe <jgg@nvidia.com>
To: David Matlack <dmatlack@google.com>
Cc: "Bjorn Helgaas" <helgaas@kernel.org>,
"Alex Williamson" <alex@shazbot.org>,
"Adithya Jayachandran" <ajayachandra@nvidia.com>,
"Alexander Graf" <graf@amazon.com>,
"Alex Mastro" <amastro@fb.com>,
"Alistair Popple" <apopple@nvidia.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Ankit Agrawal" <ankita@nvidia.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Chris Li" <chrisl@kernel.org>,
"David Rientjes" <rientjes@google.com>,
"Jacob Pan" <jacob.pan@linux.microsoft.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"Josh Hilke" <jrhilke@google.com>,
"Kevin Tian" <kevin.tian@intel.com>,
kexec@lists.infradead.org, kvm@vger.kernel.org,
"Leon Romanovsky" <leon@kernel.org>,
"Leon Romanovsky" <leonro@nvidia.com>,
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" <lukas@wunner.de>,
"Michał Winiarski" <michal.winiarski@intel.com>,
"Mike Rapoport" <rppt@kernel.org>,
"Parav Pandit" <parav@nvidia.com>,
"Pasha Tatashin" <pasha.tatashin@soleen.com>,
"Pranjal Shrivastava" <praan@google.com>,
"Pratyush Yadav" <pratyush@kernel.org>,
"Raghavendra Rao Ananta" <rananta@google.com>,
"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
"Saeed Mahameed" <saeedm@nvidia.com>,
"Samiullah Khawaja" <skhawaja@google.com>,
"Shuah Khan" <skhan@linuxfoundation.org>,
"Thomas Hellström" <thomas.hellstrom@linux.intel.com>,
"Tomita Moeko" <tomitamoeko@gmail.com>,
"Vipin Sharma" <vipinsh@google.com>,
"Vivek Kasireddy" <vivek.kasireddy@intel.com>,
"William Tu" <witu@nvidia.com>, "Yi Liu" <yi.l.liu@intel.com>,
"Zhu Yanjun" <yanjun.zhu@linux.dev>
Subject: Re: [PATCH v2 03/22] PCI: Inherit bus numbers from previous kernel during Live Update
Date: Thu, 26 Feb 2026 10:40:57 -0400 [thread overview]
Message-ID: <20260226144057.GA5933@nvidia.com> (raw)
In-Reply-To: <aZ-Dqi782aafiE_-@google.com>
On Wed, Feb 25, 2026 at 11:20:10PM +0000, David Matlack wrote:
> On 2026-02-25 04:47 PM, Bjorn Helgaas wrote:
> > On Thu, Jan 29, 2026 at 09:24:50PM +0000, David Matlack wrote:
> > > Inherit bus numbers from the previous kernel during a Live Update when
> > > one or more PCI devices are being preserved. This is necessary so that
> > > preserved devices can DMA through the IOMMU during a Live Update
> > > (changing bus numbers would break IOMMU translation).
> >
> > I think changing bus numbers would break DMA regardless of whether an
> > IOMMU is involved. Completions carrying the data for DMA reads are
> > routed back to the Requester ID of the read.
>
> Ahh, makes sense. I'll clarify the commit message in the next
> version.
More broadly you can't shouldn't the fabric topology while Memory
Enable is active.
Renumbering or readdressing the fabric requires disabling and flushing
any memory transactions.
From that reasoning it is clearer that you can't do that if the device
is expected to hitlesslly continue performing memory operations.
That may be a clearer long term basis for describing the requirements
here.
Jason
next prev parent reply other threads:[~2026-02-26 14:41 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-29 21:24 [PATCH v2 00/22] vfio/pci: Base Live Update support for VFIO device files David Matlack
2026-01-29 21:24 ` [PATCH v2 01/22] liveupdate: Export symbols needed by modules David Matlack
2026-02-24 8:26 ` Pranjal Shrivastava
2026-02-24 17:08 ` Samiullah Khawaja
2026-01-29 21:24 ` [PATCH v2 02/22] PCI: Add API to track PCI devices preserved across Live Update David Matlack
2026-02-01 6:38 ` Zhu Yanjun
2026-02-02 18:14 ` David Matlack
2026-02-04 0:10 ` Yanjun.Zhu
2026-02-20 19:03 ` David Matlack
2026-02-23 22:04 ` Samiullah Khawaja
2026-02-23 23:08 ` David Matlack
2026-02-23 23:43 ` Samiullah Khawaja
2026-02-24 0:00 ` David Matlack
2026-02-24 9:17 ` Pranjal Shrivastava
2026-02-24 17:33 ` David Matlack
2026-02-24 19:02 ` Pranjal Shrivastava
2026-02-24 19:05 ` Pranjal Shrivastava
2026-02-25 22:46 ` Bjorn Helgaas
2026-02-26 0:28 ` David Matlack
2026-01-29 21:24 ` [PATCH v2 03/22] PCI: Inherit bus numbers from previous kernel during " David Matlack
2026-02-24 9:36 ` Pranjal Shrivastava
2026-02-24 17:36 ` David Matlack
2026-02-25 22:47 ` Bjorn Helgaas
2026-02-25 23:20 ` David Matlack
2026-02-26 14:40 ` Jason Gunthorpe [this message]
2026-01-29 21:24 ` [PATCH v2 04/22] vfio/pci: Register a file handler with Live Update Orchestrator David Matlack
2026-02-06 22:37 ` Yanjun.Zhu
2026-02-06 23:14 ` David Matlack
2026-02-24 9:58 ` Pranjal Shrivastava
2026-02-25 21:33 ` Alex Williamson
2026-02-25 22:06 ` Pranjal Shrivastava
2026-02-25 22:29 ` Pranjal Shrivastava
2026-02-25 22:50 ` Samiullah Khawaja
2026-02-25 23:15 ` David Matlack
2026-02-25 23:54 ` Samiullah Khawaja
2026-01-29 21:24 ` [PATCH v2 05/22] vfio/pci: Preserve vfio-pci device files across Live Update David Matlack
2026-02-23 22:29 ` Samiullah Khawaja
2026-02-24 18:37 ` Pranjal Shrivastava
2026-02-24 19:16 ` David Matlack
2026-02-25 22:41 ` Alex Williamson
2026-02-25 23:41 ` David Matlack
2026-01-29 21:24 ` [PATCH v2 06/22] vfio/pci: Retrieve preserved device files after " David Matlack
2026-02-23 23:27 ` Samiullah Khawaja
2026-02-24 19:19 ` Pranjal Shrivastava
2026-01-29 21:24 ` [PATCH v2 07/22] vfio/pci: Notify PCI subsystem about devices preserved across " David Matlack
2026-02-25 7:55 ` Pranjal Shrivastava
2026-02-26 0:45 ` David Matlack
2026-01-29 21:24 ` [PATCH v2 08/22] vfio: Enforce preserved devices are retrieved via LIVEUPDATE_SESSION_RETRIEVE_FD David Matlack
2026-02-25 8:03 ` Pranjal Shrivastava
2026-01-29 21:24 ` [PATCH v2 09/22] vfio/pci: Store incoming Live Update state in struct vfio_pci_core_device David Matlack
2026-02-25 8:38 ` Pranjal Shrivastava
2026-02-26 0:51 ` David Matlack
2026-01-29 21:24 ` [PATCH v2 10/22] vfio/pci: Skip reset of preserved device after Live Update David Matlack
2026-01-29 22:21 ` Jacob Pan
2026-01-29 22:33 ` David Matlack
2026-01-30 0:31 ` Jacob Pan
2026-01-29 21:24 ` [PATCH v2 11/22] docs: liveupdate: Document VFIO device file preservation David Matlack
2026-01-29 21:24 ` [PATCH v2 12/22] selftests/liveupdate: Move luo_test_utils.* into a reusable library David Matlack
2026-01-29 21:25 ` [PATCH v2 13/22] selftests/liveupdate: Add helpers to preserve/retrieve FDs David Matlack
2026-01-29 21:25 ` [PATCH v2 14/22] vfio: selftests: Build liveupdate library in VFIO selftests David Matlack
2026-01-29 21:25 ` [PATCH v2 15/22] vfio: selftests: Add Makefile support for TEST_GEN_PROGS_EXTENDED David Matlack
2026-01-29 21:25 ` [PATCH v2 16/22] vfio: selftests: Add vfio_pci_liveupdate_uapi_test David Matlack
2026-01-29 21:25 ` [PATCH v2 17/22] vfio: selftests: Initialize vfio_pci_device using a VFIO cdev FD David Matlack
2026-01-29 21:25 ` [PATCH v2 18/22] vfio: selftests: Add vfio_pci_liveupdate_kexec_test David Matlack
2026-01-29 21:25 ` [PATCH v2 19/22] vfio: selftests: Expose iommu_modes to tests David Matlack
2026-01-29 21:25 ` [PATCH v2 20/22] vfio: selftests: Expose low-level helper routines for setting up struct vfio_pci_device David Matlack
2026-01-29 21:25 ` [PATCH v2 21/22] vfio: selftests: Verify that opening VFIO device fails during Live Update David Matlack
2026-01-29 21:25 ` [PATCH v2 22/22] vfio: selftests: Add continuous DMA to vfio_pci_liveupdate_kexec_test David Matlack
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