From: Hou Zhiqiang Zhiqiang.Hou@nxp.com
[ Upstream commit 15b23906347c0af8778d1d4edeea415290342d35 ]
NXP Layerscape (ls1028a, ls2088a), dra7xxx and imx6 platforms are either programmed or statically configured to forward the error triggered by a link-down state (eg no connected endpoint device) on the system bus for PCI configuration transactions; these errors are reported as an SError at system level, which is fatal.
Enumerating a PCI tree when the PCIe link is down is not sensible either, so even if the link-up check is racy (link can go down after map_bus() is called) add a link-up check in map_bus() to prevent issuing configuration transactions when the link is down.
SError report:
SError Interrupt on CPU2, code 0xbf000002 -- SError CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc5-next-20200914-00001-gf965d3ec86fa #67 Hardware name: LS1046A RDB Board (DT) pstate: 20000085 (nzCv daIf -PAN -UAO BTYPE=--) pc : pci_generic_config_read+0x3c/0xe0 lr : pci_generic_config_read+0x24/0xe0 sp : ffff80001003b7b0 x29: ffff80001003b7b0 x28: ffff80001003ba74 x27: ffff000971d96800 x26: ffff00096e77e0a8 x25: ffff80001003b874 x24: ffff80001003b924 x23: 0000000000000004 x22: 0000000000000000 x21: 0000000000000000 x20: ffff80001003b874 x19: 0000000000000004 x18: ffffffffffffffff x17: 00000000000000c0 x16: fffffe0025981840 x15: ffffb94c75b69948 x14: 62203a383634203a x13: 666e6f635f726568 x12: 202c31203d207265 x11: 626d756e3e2d7375 x10: 656877202c307830 x9 : 203d206e66766564 x8 : 0000000000000908 x7 : 0000000000000908 x6 : ffff800010900000 x5 : ffff00096e77e080 x4 : 0000000000000000 x3 : 0000000000000003 x2 : 84fa3440ff7e7000 x1 : 0000000000000000 x0 : ffff800010034000 Kernel panic - not syncing: Asynchronous SError Interrupt CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc5-next-20200914-00001-gf965d3ec86fa #67 Hardware name: LS1046A RDB Board (DT) Call trace: dump_backtrace+0x0/0x1c0 show_stack+0x18/0x28 dump_stack+0xd8/0x134 panic+0x180/0x398 add_taint+0x0/0xb0 arm64_serror_panic+0x78/0x88 do_serror+0x68/0x180 el1_error+0x84/0x100 pci_generic_config_read+0x3c/0xe0 dw_pcie_rd_other_conf+0x78/0x110 pci_bus_read_config_dword+0x88/0xe8 pci_bus_generic_read_dev_vendor_id+0x30/0x1b0 pci_bus_read_dev_vendor_id+0x4c/0x78 pci_scan_single_device+0x80/0x100
Link: https://lore.kernel.org/r/20200916054130.8685-1-Zhiqiang.Hou@nxp.com Signed-off-by: Hou Zhiqiang Zhiqiang.Hou@nxp.com [lorenzo.pieralisi@arm.com: rewrote the commit log, remove Fixes tag] Signed-off-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/controller/dwc/pcie-designware-host.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c index 0a4a5aa6fe469..d78222ff954ec 100644 --- a/drivers/pci/controller/dwc/pcie-designware-host.c +++ b/drivers/pci/controller/dwc/pcie-designware-host.c @@ -526,6 +526,17 @@ static int dw_pcie_access_other_conf(struct pcie_port *pp, struct pci_bus *bus, void __iomem *va_cfg_base; struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+ /* + * Checking whether the link is up here is a last line of defense + * against platforms that forward errors on the system bus as + * SError upon PCI configuration transactions issued when the link + * is down. This check is racy by definition and does not stop + * the system from triggering an SError if the link goes down + * after this check is performed. + */ + if (!dw_pcie_link_up(pci)) + return NULL; + busdev = PCIE_ATU_BUS(bus->number) | PCIE_ATU_DEV(PCI_SLOT(devfn)) | PCIE_ATU_FUNC(PCI_FUNC(devfn));