From f3b70cc7994be7378c34dac01a7cfec4b001072d Mon Sep 17 00:00:00 2001 From: Håkon Bugge Date: Thu, 29 Jan 2026 18:52:32 +0100 Subject: PCI: Initialize RCB from pci_configure_device() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit 1a6845aaa6de81f95959b380b45de8f10d6a8502 ] Commit e42010d8207f ("PCI: Set Read Completion Boundary to 128 iff Root Port supports it (_HPX)") worked around a bogus _HPX type 2 record, which caused program_hpx_type2() to set the RCB in an endpoint even though the Root Port did not have the RCB bit set. e42010d8207f fixed that by setting the RCB in the endpoint only when it was set in the Root Port. In retrospect, program_hpx_type2() is intended for AER-related settings, and the RCB should be configured elsewhere so it doesn't depend on the presence or contents of an _HPX record. Explicitly program the RCB from pci_configure_device() so it matches the Root Port's RCB. The Root Port may not be visible to virtualized guests; in that case, leave RCB alone. Fixes: e42010d8207f ("PCI: Set Read Completion Boundary to 128 iff Root Port supports it (_HPX)") Signed-off-by: Håkon Bugge Signed-off-by: Bjorn Helgaas Link: https://patch.msgid.link/20260129175237.727059-2-haakon.bugge@oracle.com Signed-off-by: Sasha Levin --- drivers/pci/probe.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 4a72a0163a86..ea7db1bd2114 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2284,6 +2284,37 @@ static void pci_configure_serr(struct pci_dev *dev) } } +static void pci_configure_rcb(struct pci_dev *dev) +{ + struct pci_dev *rp; + u16 rp_lnkctl; + + /* + * Per PCIe r7.0, sec 7.5.3.7, RCB is only meaningful in Root Ports + * (where it is read-only), Endpoints, and Bridges. It may only be + * set for Endpoints and Bridges if it is set in the Root Port. For + * Endpoints, it is 'RsvdP' for Virtual Functions. + */ + if (!pci_is_pcie(dev) || + pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT || + pci_pcie_type(dev) == PCI_EXP_TYPE_UPSTREAM || + pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM || + pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC || + dev->is_virtfn) + return; + + /* Root Port often not visible to virtualized guests */ + rp = pcie_find_root_port(dev); + if (!rp) + return; + + pcie_capability_read_word(rp, PCI_EXP_LNKCTL, &rp_lnkctl); + pcie_capability_clear_and_set_word(dev, PCI_EXP_LNKCTL, + PCI_EXP_LNKCTL_RCB, + (rp_lnkctl & PCI_EXP_LNKCTL_RCB) ? + PCI_EXP_LNKCTL_RCB : 0); +} + static void pci_configure_device(struct pci_dev *dev) { pci_configure_mps(dev); @@ -2292,6 +2323,7 @@ static void pci_configure_device(struct pci_dev *dev) pci_configure_ltr(dev); pci_configure_eetlp_prefix(dev); pci_configure_serr(dev); + pci_configure_rcb(dev); pci_acpi_program_hp_params(dev); } -- cgit v1.2.3