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Sat, 24 Oct 2026 17:08:44 -0700 (PDT) Received: from gmail.com ([2a03:2880:1fff:41::]) by smtp.gmail.com with ESMTPSA id 00721157ae682-8b166ded0aasm14148067b3.8.2026.10.24.17.08.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 24 Oct 2026 17:08:43 -0700 (PDT) From: Matthew Wood To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, kbusch@kernel.org, Nikita Vetoshkin Subject: [PATCH 3/5] PCI: Add pcie_capability_user_read_{word,dword}() Date: Sat, 24 Oct 2026 17:08:31 -0700 Message-ID: <20261025000836.58294-4-thepacketgeek@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261025000836.58294-1-thepacketgeek@gmail.com> References: <20261025000836.58294-1-thepacketgeek@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit pcie_capability_read_word() and pcie_capability_read_dword() use the kernel config accessors which don't check block_cfg_access, so they can't be used for reads on behalf of userspace that should wait for a reset (or other pci_cfg_access_lock() holder) to finish. Add pcie_capability_user_read_word() and pcie_capability_user_read_dword() helpers, which provide the same function using the user config accessors. These are for use within the PCI core, so they are declared in drivers/pci/pci.h and not exported. Signed-off-by: Matthew Wood Tested-by: Nikita Vetoshkin --- drivers/pci/access.c | 50 ++++++++++++++++++++++++++++++++++++++++++++ drivers/pci/pci.h | 2 ++ 2 files changed, 52 insertions(+) diff --git a/drivers/pci/access.c b/drivers/pci/access.c index 18a206bb2a94..ff5a16236758 100644 --- a/drivers/pci/access.c +++ b/drivers/pci/access.c @@ -490,6 +490,56 @@ int pcie_capability_read_dword(struct pci_dev *dev, int pos, u32 *val) } EXPORT_SYMBOL(pcie_capability_read_dword); +/* + * Same as pcie_capability_read_{word,dword}(), but using the user config + * accessors. Returns 0 on success, negative values indicate error. + */ +int pcie_capability_user_read_word(struct pci_dev *dev, int pos, u16 *val) +{ + int ret; + + *val = 0; + if (pos & 1) + return -EINVAL; + + if (pcie_capability_reg_implemented(dev, pos)) { + ret = pci_user_read_config_word(dev, pci_pcie_cap(dev) + pos, + val); + if (ret) + *val = 0; + return ret; + } + + if (pci_is_pcie(dev) && pcie_downstream_port(dev) && + pos == PCI_EXP_SLTSTA) + *val = PCI_EXP_SLTSTA_PDS; + + return 0; +} + +int pcie_capability_user_read_dword(struct pci_dev *dev, int pos, u32 *val) +{ + int ret; + + *val = 0; + if (pos & 3) + return -EINVAL; + + if (pcie_capability_reg_implemented(dev, pos)) { + ret = pci_user_read_config_dword(dev, pci_pcie_cap(dev) + pos, + val); + if (ret) + *val = 0; + return ret; + } + + if (pci_is_pcie(dev) && pcie_downstream_port(dev) && + pos == PCI_EXP_SLTSTA) + *val = PCI_EXP_SLTSTA_PDS; + + return 0; +} + int pcie_capability_write_word(struct pci_dev *dev, int pos, u16 val) { if (pos & 1) diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 77efa4c5c960..7c5a2ebc5706 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -128,6 +128,8 @@ extern struct mutex pci_rescan_remove_lock; bool pcie_cap_has_lnkctl(const struct pci_dev *dev); bool pcie_cap_has_lnkctl2(const struct pci_dev *dev); bool pcie_cap_has_rtctl(const struct pci_dev *dev); +int pcie_capability_user_read_word(struct pci_dev *dev, int pos, u16 *val); +int pcie_capability_user_read_dword(struct pci_dev *dev, int pos, u32 *val); /* Standard Capability finder */ /** -- 2.53.0-Meta