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[34.127.9.76]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b9cae67196sm5018815ad.79.2026.04.30.14.16.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Apr 2026 14:16:07 -0700 (PDT) Date: Thu, 30 Apr 2026 21:16:03 +0000 From: David Matlack To: Samiullah Khawaja Cc: iommu@lists.linux.dev, kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Adithya Jayachandran , Alexander Graf , Alex Williamson , Bjorn Helgaas , Chris Li , David Rientjes , Jacob Pan , Jason Gunthorpe , Joerg Roedel , Jonathan Corbet , Josh Hilke , Leon Romanovsky , Lukas Wunner , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Robin Murphy , Saeed Mahameed , Shuah Khan , Will Deacon , William Tu , Yi Liu Subject: Re: [PATCH v4 02/11] PCI: liveupdate: Track outgoing preserved PCI devices Message-ID: References: <20260423212316.3431746-1-dmatlack@google.com> <20260423212316.3431746-3-dmatlack@google.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On 2026-04-28 05:35 PM, Samiullah Khawaja wrote: > On Tue, Apr 28, 2026 at 05:24:53PM +0000, Samiullah Khawaja wrote: > > On Thu, Apr 23, 2026 at 09:23:06PM +0000, David Matlack wrote: > > > Add APIs to allow drivers to notify the PCI core of which devices are > > > being preserved across a Live Update for the next kernel, i.e. > > > "outgoing" devices. > > > > > > Drivers must notify the PCI core when devices are preserved so that the > > > PCI core can update its FLB data (struct pci_ser) and track the list of > > > outgoing devices. pci_liveupdate_preserve() notifies the PCI core that a > > > device must be preserved across Live Update. pci_liveupdate_unpreserve() > > > reverses this (cancels the preservation of the device). > > > > > > This tracking ensures the PCI core is fully aware of which devices may > > > need special handling during shutdown and kexec, and so that it can be > > > handed off to the next kernel. > > > > > > Signed-off-by: David Matlack > > > --- > > > drivers/pci/liveupdate.c | 101 ++++++++++++++++++++++++++++++++++++ > > > include/linux/kho/abi/pci.h | 7 +-- > > > include/linux/pci.h | 26 ++++++++++ > > > 3 files changed, 131 insertions(+), 3 deletions(-) > > > > > > diff --git a/include/linux/kho/abi/pci.h b/include/linux/kho/abi/pci.h > > > index 5c0e92588c00..5b4c8d9e462c 100644 > > > --- a/include/linux/kho/abi/pci.h > > > +++ b/include/linux/kho/abi/pci.h > > > @@ -23,19 +23,20 @@ > > > * incrementing the version number in the PCI_LUO_FLB_COMPATIBLE string. > > > */ > > > > > > -#define PCI_LUO_FLB_COMPATIBLE "pci-v1" > > > +#define PCI_LUO_FLB_COMPATIBLE "pci-v2" > > > > > > /** > > > * struct pci_dev_ser - Serialized state about a single PCI device. > > > * > > > * @domain: The device's PCI domain number (segment). > > > * @bdf: The device's PCI bus, device, and function number. > > > - * @reserved: Reserved (to naturally align struct pci_dev_ser). > > > + * @refcount: Reference count used by the PCI core to keep track of whether it > > > + * is done using a device's struct pci_dev_ser. > > nit: I was wondering why is this named refcount and why it is needed. It > seems you are using it to track the preservation dependency between > parent devices and leaf. Maybe add a comment to clarify that. Ack, I will clarify that more in the kerneldoc in v5, thanks.