[PATCH] powerpc/pci: Enable PCI domains in /proc when PCI bus numbers are not unique
From: Pali Rohár
Date: Sat Aug 20 2022 - 07:51:36 EST
On 32-bit powerpc systems with more PCIe controllers and more PCI domains,
where on more PCI domains are same PCI numbers, when kernel is compiled
with CONFIG_PROC_FS=y and CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT=y
options, kernel prints "proc_dir_entry 'pci/01' already registered" error
message.
[ 1.708861] ------------[ cut here ]------------
[ 1.713429] proc_dir_entry 'pci/01' already registered
[ 1.718595] WARNING: CPU: 0 PID: 1 at fs/proc/generic.c:377 proc_register+0x1a8/0x1ac
[ 1.726361] Modules linked in:
[ 1.729404] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 5.19.0-rc5-0caacb197b677410bdac81bc34f05235+ #109
[ 1.740183] NIP: c02846e8 LR: c02846e8 CTR: c0015154
[ 1.745225] REGS: c146fc90 TRAP: 0700 Tainted: G W (5.19.0-rc5-0caacb197b677410bdac81bc34f05235+)
[ 1.755657] MSR: 00029000 <CE,EE,ME> CR: 28000822 XER: 00000000
[ 1.761829]
[ 1.761829] GPR00: c02846e8 c146fd80 c14a8000 0000002a 3fffefff c146fc40 c146fc38 00000000
[ 1.761829] GPR08: 3fffefff 00000000 00000000 c10ac04c 24000824 00000000 c0004548 00000000
[ 1.761829] GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000007
[ 1.761829] GPR24: c10000d0 c167da54 c167da00 c1120000 c167dd6c c10b4abc c167dc58 c167dd00
[ 1.796707] NIP [c02846e8] proc_register+0x1a8/0x1ac
[ 1.801663] LR [c02846e8] proc_register+0x1a8/0x1ac
[ 1.806532] Call Trace:
[ 1.808966] [c146fd80] [c02846e8] proc_register+0x1a8/0x1ac (unreliable)
[ 1.815659] [c146fdb0] [c028481c] _proc_mkdir+0x78/0xa4
[ 1.820875] [c146fdd0] [c05a92e4] pci_proc_attach_device+0x11c/0x168
[ 1.827221] [c146fe10] [c101f7a4] pci_proc_init+0x80/0x98
[ 1.832611] [c146fe30] [c0004150] do_one_initcall+0x80/0x284
[ 1.838262] [c146fea0] [c10011a8] kernel_init_freeable+0x1f4/0x2a0
[ 1.844434] [c146fee0] [c000456c] kernel_init+0x24/0x150
[ 1.849737] [c146ff00] [c001326c] ret_from_kernel_thread+0x5c/0x64
[ 1.855910] Instruction dump:
[ 1.858866] 83810020 83a10024 83c10028 83e1002c 38210030 4e800020 809a0064 3c60c0a8
[ 1.866602] 7f85e378 3863af28 4cc63182 4bdb8155 <0fe00000> 9421ffe0 39200000 7c0802a6
[ 1.874513] ---[ end trace 0000000000000000 ]---
This regression started appearing after commit 566356813082 ("powerpc/pci:
Add config option for using all 256 PCI buses") in case in each mPCIe slot
is connected PCIe card and therefore PCI bus 1 is populated in for every
PCIe controller / PCI domain.
The reason is that PCI procfs code expects that when PCI bus numbers are
not unique across all PCI domains, function pci_proc_domain() returns true
for domain dependent buses.
Fix this issue by setting PCI_ENABLE_PROC_DOMAINS and PCI_COMPAT_DOMAIN_0
flags for 32-bit powerpc code when CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT
is enabled. Same approach is already implemented for 64-bit powerpc code
(where PCI bus numbers are always domain dependent).
Fixes: 566356813082 ("powerpc/pci: Add config option for using all 256 PCI buses")
Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
---
arch/powerpc/kernel/pci_32.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/powerpc/kernel/pci_32.c b/arch/powerpc/kernel/pci_32.c
index ffc4e1928c80..8acbc9592ebb 100644
--- a/arch/powerpc/kernel/pci_32.c
+++ b/arch/powerpc/kernel/pci_32.c
@@ -249,6 +249,15 @@ static int __init pcibios_init(void)
printk(KERN_INFO "PCI: Probing PCI hardware\n");
+#ifdef CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT
+ /*
+ * Enable PCI domains in /proc when PCI bus numbers are not unique
+ * across all PCI domains to prevent conflicts. And keep PCI domain 0
+ * backward compatible in /proc for video cards.
+ */
+ pci_add_flags(PCI_ENABLE_PROC_DOMAINS | PCI_COMPAT_DOMAIN_0);
+#endif
+
if (pci_has_flag(PCI_REASSIGN_ALL_BUS))
pci_assign_all_buses = 1;
--
2.20.1