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AJvYcCXQhAgmxTesdJaW8QFhHjeLQ3wwuVK1GVzM56EOTe00FpAaeF0YN6gPeGYC5wufe314B8ZFzLawwQ==@kvack.org X-Gm-Message-State: AOJu0YzX3Jxlm0LOGjl3gc6upTz6CSmRmcC6+YdVn7UH/CfLGWs8sXXj gWRn5NRrsJco6ya8XkSnsZBBV01SnVtObgqMKH94aBk8IPrkew7wuF1G+3eljkJNIL1bmH143Jm xSUCzOmPHevQGVA== X-Received: from pjblb16.prod.google.com ([2002:a17:90b:4a50:b0:352:b92b:ef8]) (user=dmatlack job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:28c5:b0:343:684c:f8a0 with SMTP id 98e67ed59e1d1-3543b3ae12dmr762757a91.23.1769721942669; Thu, 29 Jan 2026 13:25:42 -0800 (PST) Date: Thu, 29 Jan 2026 21:24:50 +0000 In-Reply-To: <20260129212510.967611-1-dmatlack@google.com> Mime-Version: 1.0 References: <20260129212510.967611-1-dmatlack@google.com> X-Mailer: git-send-email 2.53.0.rc1.225.gd81095ad13-goog Message-ID: <20260129212510.967611-4-dmatlack@google.com> Subject: [PATCH v2 03/22] PCI: Inherit bus numbers from previous kernel during Live Update From: David Matlack To: Alex Williamson Cc: Adithya Jayachandran , Alexander Graf , Alex Mastro , Alistair Popple , Andrew Morton , Ankit Agrawal , Bjorn Helgaas , Chris Li , David Matlack , David Rientjes , Jacob Pan , 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=20Winiarski?=" , 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=20Hellstr=C3=B6m?=" , Tomita Moeko , Vipin Sharma , Vivek Kasireddy , William Tu , Yi Liu , Zhu Yanjun Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: DDAF8180007 X-Stat-Signature: jktcythhb4akigtzq5is1g5ect17njen X-Rspam-User: X-HE-Tag: 1769721943-804143 X-HE-Meta: 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 CiOKkp9h 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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). Signed-off-by: David Matlack --- drivers/pci/probe.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index af6356c5a156..ca6e5f79debb 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1351,6 +1351,20 @@ static bool pci_ea_fixed_busnrs(struct pci_dev *dev, u8 *sec, u8 *sub) return true; } +static bool pci_assign_all_busses(void) +{ + /* + * During a Live Update where devices are preserved by the previous + * kernel, inherit all bus numbers assigned by the previous kernel. Bus + * numbers must remain stable for preserved devices so that they can + * perform DMA during the Live Update uninterrupted. + */ + if (pci_liveupdate_incoming_nr_devices()) + return false; + + return pcibios_assign_all_busses(); +} + /* * pci_scan_bridge_extend() - Scan buses behind a bridge * @bus: Parent bus the bridge is on @@ -1378,6 +1392,7 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev, int max, unsigned int available_buses, int pass) { + bool assign_all_busses = pci_assign_all_busses(); struct pci_bus *child; int is_cardbus = (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS); u32 buses, i, j = 0; @@ -1424,7 +1439,7 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev, pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl & ~PCI_BRIDGE_CTL_MASTER_ABORT); - if ((secondary || subordinate) && !pcibios_assign_all_busses() && + if ((secondary || subordinate) && !assign_all_busses && !is_cardbus && !broken) { unsigned int cmax, buses; @@ -1467,7 +1482,7 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev, * do in the second pass. */ if (!pass) { - if (pcibios_assign_all_busses() || broken || is_cardbus) + if (assign_all_busses || broken || is_cardbus) /* * Temporarily disable forwarding of the @@ -1542,7 +1557,7 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev, max+i+1)) break; while (parent->parent) { - if ((!pcibios_assign_all_busses()) && + if (!assign_all_busses && (parent->busn_res.end > max) && (parent->busn_res.end <= max+i)) { j = 1; -- 2.53.0.rc1.225.gd81095ad13-goog