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Fri, 18 Sep 2026 13:07:01 -0700 (PDT) Date: Fri, 18 Sep 2026 20:06:36 +0000 In-Reply-To: <20260918200640.887030-1-dmatlack@google.com> Mime-Version: 1.0 References: <20260918200640.887030-1-dmatlack@google.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Message-ID: <20260918200640.887030-11-dmatlack@google.com> Subject: [PATCH v9 10/13] PCI: liveupdate: Adopt ARI Forwarding Enable on preserved bridges From: David Matlack To: kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org Cc: Adithya Jayachandran , Alexander Graf , Alex Williamson , Bjorn Helgaas , Chris Li , David Matlack , David Rientjes , Jacob Pan , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Leon Romanovsky , Lukas Wunner , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Randy Dunlap , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Vipin Sharma , William Tu , Yi Liu Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260918_130703_707482_5433B352 X-CRM114-Status: GOOD ( 17.04 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org Adopt the ARI Forwarding Enable bit on preserved bridges and update pci_dev->ari_enabled accordingly during a Live Update. This ensures that the preserved devices on the bridge's secondary bus can be identified with the same expanded 8-bit function number after a Live Update. Reviewed-by: Bjorn Helgaas Reviewed-by: Pranjal Shrivastava Signed-off-by: David Matlack --- drivers/pci/liveupdate.c | 30 ++++++++++++++++++++++++++++++ drivers/pci/liveupdate.h | 6 ++++++ drivers/pci/pci.c | 8 +++++++- 3 files changed, 43 insertions(+), 1 deletion(-) diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c index 0145399b3834..3c9a10a892fc 100644 --- a/drivers/pci/liveupdate.c +++ b/drivers/pci/liveupdate.c @@ -189,6 +189,10 @@ * way after Live Update and ensures that IOMMU groups do not change. Note * that a device will use its adopted ACS controls for the lifetime of its * struct pci_dev (i.e. even after pci_liveupdate_finish()). + * + * * The PCI core adopts ARI Forwarding Enable on all bridges with downstream + * preserved devices to ensure that all preserved devices on the bridge's + * secondary bus are addressable after the Live Update. */ #define pr_fmt(fmt) "PCI: liveupdate: " fmt @@ -904,6 +908,32 @@ int pci_liveupdate_adopt_acs(struct pci_dev *dev) return 0; } +/** + * pci_liveupdate_adopt_ari() - Adopt ARI configuration + * @dev: The PCI device to adopt ARI configuration for + * + * For devices preserved across a Live Update, read the ARI state from + * hardware and adopt it. This ensures the device continues to use the ARI + * configuration established by the previous kernel. + * + * Return: 0 on success, or -EINVAL if the device was not preserved. + */ +int pci_liveupdate_adopt_ari(struct pci_dev *dev) +{ + u16 val; + + guard(rwsem_read)(&pci_liveupdate.rwsem); + + if (!dev->liveupdate.incoming) + return -EINVAL; + + pcie_capability_read_word(dev, PCI_EXP_DEVCTL2, &val); + + /* Safe to modify dev->ari_enabled bitfield during enumeration. */ + dev->ari_enabled = !!(val & PCI_EXP_DEVCTL2_ARI); + return 0; +} + /** * pci_liveupdate_is_incoming() - Check if a device is incoming-preserved * @dev: The PCI device to check diff --git a/drivers/pci/liveupdate.h b/drivers/pci/liveupdate.h index d4721ffcecb2..90b2754ecc0c 100644 --- a/drivers/pci/liveupdate.h +++ b/drivers/pci/liveupdate.h @@ -16,6 +16,7 @@ void pci_liveupdate_cleanup_device(struct pci_dev *dev); bool pci_liveupdate_preserve_bus_numbers(void); bool pci_liveupdate_refuse_bus_numbers(struct pci_bus *bus, struct pci_dev *dev); int pci_liveupdate_adopt_acs(struct pci_dev *dev); +int pci_liveupdate_adopt_ari(struct pci_dev *dev); #else static inline void pci_liveupdate_setup_device(struct pci_dev *dev) { @@ -40,6 +41,11 @@ static inline int pci_liveupdate_adopt_acs(struct pci_dev *dev) { return -EINVAL; } + +static inline int pci_liveupdate_adopt_ari(struct pci_dev *dev) +{ + return -EINVAL; +} #endif #endif /* DRIVERS_PCI_LIVEUPDATE_H */ diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 47d8229115b8..0ae405b86b2f 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3625,7 +3625,7 @@ void pci_configure_ari(struct pci_dev *dev) u32 cap; struct pci_dev *bridge; - if (pcie_ari_disabled || !pci_is_pcie(dev) || dev->devfn) + if (!pci_is_pcie(dev) || dev->devfn) return; bridge = dev->bus->self; @@ -3636,6 +3636,12 @@ void pci_configure_ari(struct pci_dev *dev) if (!(cap & PCI_EXP_DEVCAP2_ARI)) return; + if (!pci_liveupdate_adopt_ari(bridge)) + return; + + if (pcie_ari_disabled) + return; + if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI)) { pcie_capability_set_word(bridge, PCI_EXP_DEVCTL2, PCI_EXP_DEVCTL2_ARI); -- 2.55.0.1082.g2b9226bbc0-goog