drivers/pci/msi/irqdomain.c | 7 +++++-- drivers/pci/msi/msi.c | 4 ++++ 2 files changed, 9 insertions(+), 2 deletions(-)
Alexandre observed a warning emitted from pci_msi_setup_msi_irqs() on a
RISCV platform which does not provide PCI/MSI support:
WARNING: CPU: 1 PID: 1 at drivers/pci/msi/msi.h:121 pci_msi_setup_msi_irqs+0x2c/0x32
__pci_enable_msix_range+0x30c/0x596
pci_msi_setup_msi_irqs+0x2c/0x32
pci_alloc_irq_vectors_affinity+0xb8/0xe2
RISCV uses hierarchical interrupt domains and correctly does not implement
the legacy fallback. The warning triggers from the legacy fallback stub.
That warning is bogus as the PCI/MSI layer knows whether a PCI/MSI parent
domain is associated with the device or not. There is a check for MSI-X,
which has a legacy assumption. But that legacy fallback assumption is only
valid when legacy support is enabled, but otherwise the check should simply
return -ENOTSUPP.
Loongarch tripped over the same problem and blindly enabled legacy support
without implementing the legacy fallbacks. There are weak implementations
which return an error, so the problem was papered over.
Correct pci_msi_domain_supports() to evaluate the legacy mode and add
the missing supported check into the MSI enable path to complete it.
Fixes: d2a463b29741 ("PCI/MSI: Reject multi-MSI early")
Reported-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: stable@vger.kernel.org
---
drivers/pci/msi/irqdomain.c | 7 +++++--
drivers/pci/msi/msi.c | 4 ++++
2 files changed, 9 insertions(+), 2 deletions(-)
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -350,8 +350,11 @@ bool pci_msi_domain_supports(struct pci_
domain = dev_get_msi_domain(&pdev->dev);
- if (!domain || !irq_domain_is_hierarchy(domain))
- return mode == ALLOW_LEGACY;
+ if (!domain || !irq_domain_is_hierarchy(domain)) {
+ if (IS_ENABLED(CONFIG_PCI_MSI_ARCH_FALLBACKS))
+ return mode == ALLOW_LEGACY;
+ return false;
+ }
if (!irq_domain_is_msi_parent(domain)) {
/*
--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -433,6 +433,10 @@ int __pci_enable_msi_range(struct pci_de
if (WARN_ON_ONCE(dev->msi_enabled))
return -EINVAL;
+ /* Test for the availability of MSI support */
+ if (!pci_msi_domain_supports(dev, 0, ALLOW_LEGACY))
+ return -ENOTSUPP;
+
nvec = pci_msi_vec_count(dev);
if (nvec < 0)
return nvec;Control: forwarded -1 https://lore.kernel.org/lkml/abE_QoS5DM-ZltaV@monoceros
#regzbot introduced: a60b990798eb17433d0283788280422b1bd94b18
#regzbot from: "Aaron D. Johnson" <debbugreporter@fnord.greeley.co.us>
#regzbot monitor: https://bugs.debian.org/1127635
Hello,
On Sat, Dec 14, 2024 at 12:50:18PM +0100, Thomas Gleixner wrote:
> Alexandre observed a warning emitted from pci_msi_setup_msi_irqs() on a
> RISCV platform which does not provide PCI/MSI support:
>
> WARNING: CPU: 1 PID: 1 at drivers/pci/msi/msi.h:121 pci_msi_setup_msi_irqs+0x2c/0x32
> __pci_enable_msix_range+0x30c/0x596
> pci_msi_setup_msi_irqs+0x2c/0x32
> pci_alloc_irq_vectors_affinity+0xb8/0xe2
>
> RISCV uses hierarchical interrupt domains and correctly does not implement
> the legacy fallback. The warning triggers from the legacy fallback stub.
>
> That warning is bogus as the PCI/MSI layer knows whether a PCI/MSI parent
> domain is associated with the device or not. There is a check for MSI-X,
> which has a legacy assumption. But that legacy fallback assumption is only
> valid when legacy support is enabled, but otherwise the check should simply
> return -ENOTSUPP.
>
> Loongarch tripped over the same problem and blindly enabled legacy support
> without implementing the legacy fallbacks. There are weak implementations
> which return an error, so the problem was papered over.
>
> Correct pci_msi_domain_supports() to evaluate the legacy mode and add
> the missing supported check into the MSI enable path to complete it.
>
> Fixes: d2a463b29741 ("PCI/MSI: Reject multi-MSI early")
> Reported-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> Cc: stable@vger.kernel.org
this patch became a60b990798eb17433d0283788280422b1bd94b18 in v6.13-rc5
and was backported to 6.12.y and 6.6.y (aed157301c65 and b1f7476e07b9
respectively).
A Debian user (Aaron, on Cc:) on powerpc has boot problems and bisected
them to this commit. The relevant boot log of the failure is:
[ 2.643879] BUG: Kernel NULL pointer dereference on read at 0x00000000
[ 2.643891] Faulting instruction address: 0xc000000000a39514
[ 2.643902] Oops: Kernel access of bad area, sig: 11 [#1]
[ 2.643909] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
[ 2.643920] Modules linked in: ohci_pci(+) ehci_hcd nvme_fabrics ohci_hcd nvme_keyring nvme_core usbcore nvme_auth scsi_transport_fc ipr configfs ehea(+) usb_common
[ 2.643965] CPU: 5 UID: 0 PID: 250 Comm: (udev-worker) Not tainted 6.12.17-powerpc64 #1 Debian 6.12.17-1
[ 2.643976] Hardware name: IBM,8204-E8A POWER6 (architected) 0x3e0302 0xf000002 of:IBM,EL350_118 hv:phyp pSeries
[ 2.643986] NIP: c000000000a39514 LR: c000000000a36ed8 CTR: c000000000a35820
[ 2.643995] REGS: c0000000351f6f60 TRAP: 0300 Not tainted (6.12.17-powerpc64 Debian 6.12.17-1)
[ 2.644004] MSR: 8000000000009032 <SF,EE,ME,IR,DR,RI> CR: 24222288 XER: 00000000
[ 2.644031] CFAR: c00000000000cfc4 DAR: 0000000000000000 DSISR: 40000000 IRQMASK: 0
[ 2.644031] GPR00: c000000000a36ed8 c0000000351f7200 c00000000182e200 c0000003df294000
[ 2.644031] GPR04: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
[ 2.644031] GPR08: 0000000000000001 0000000000000000 c00000000228fcc0 0000000044222288
[ 2.644031] GPR12: c000000000a35820 c00000000eeacb00 0000000000000020 0000010037fcab20
[ 2.644031] GPR16: 0000000022222248 0000000000020000 0000000000000000 00003fffebe8bb80
[ 2.644031] GPR20: 0000000000000000 c00000000204db60 c00000000204dd60 c00000000b1ae780
[ 2.644031] GPR24: 0000000000000000 00003fff8c9ac758 0000000000000000 c0000003df294000
[ 2.644031] GPR28: 0000000000000001 0000000000000000 c0000003df294000 0000000000000001
[ 2.644164] NIP [c000000000a39514] pci_msi_domain_supports (drivers/pci/msi/irqdomain.c:366)
[ 2.644181] LR [c000000000a36ed8] __pci_enable_msi_range (drivers/pci/msi/msi.c:437)
[ 2.644192] Call Trace:
[ 2.644197] [c0000000351f7200] [c0000000351f7304] 0xc0000000351f7304 (unreliable)
[ 2.644211] [c0000000351f7340] [c000000000a3578c] pci_alloc_irq_vectors_affinity (drivers/pci/msi/api.c:277)
[ 2.644225] [c0000000351f73d0] [c0003d0007d2f4d4] usb_hcd_pci_probe (drivers/usb/core/hcd-pci.c:192) usbcore
[ 2.644246] [c0000000351f7470] [c0003d00084e6030] ohci_pci_probe (drivers/usb/host/ohci-pci.c:285) ohci_pci
[ 2.644260] [c0000000351f7490] [c000000000a260e8] local_pci_probe (drivers/pci/pci-driver.c:324)
[ 2.644274] [c0000000351f7510] [c000000000a26218] pci_call_probe (drivers/pci/pci-driver.c:392 (discriminator 1))
[ 2.644287] [c0000000351f7670] [c000000000a27348] pci_device_probe (drivers/pci/pci-driver.c:452)
[ 2.644300] [c0000000351f76b0] [c000000000b2e658] really_probe (drivers/base/dd.c:579 drivers/base/dd.c:658)
[ 2.644314] [c0000000351f7740] [c000000000b2eb24] __driver_probe_device (drivers/base/dd.c:800)
[ 2.644327] [c0000000351f77c0] [c000000000b2edc4] driver_probe_device (drivers/base/dd.c:831)
[ 2.644340] [c0000000351f7800] [c000000000b2f188] __driver_attach (drivers/base/dd.c:1217)
[ 2.644352] [c0000000351f7880] [c000000000b2ac64] bus_for_each_dev (drivers/base/bus.c:370)
[ 2.644365] [c0000000351f78e0] [c000000000b2dac4] driver_attach (drivers/base/dd.c:1234)
[ 2.644377] [c0000000351f7900] [c000000000b2cd98] bus_add_driver (drivers/base/bus.c:675)
[ 2.644389] [c0000000351f7990] [c000000000b30ae4] driver_register (drivers/base/driver.c:246)
[ 2.644402] [c0000000351f7a00] [c000000000a24f88] __pci_register_driver (drivers/pci/pci-driver.c:1450)
[ 2.644415] [c0000000351f7a20] [c0003d00084e6800] ohci_pci_init (drivers/usb/host/ohci-pci.c:308) ohci_pci
[ 2.644429] [c0000000351f7a50] [c00000000000fd60] do_one_initcall (init/main.c:1269)
[ 2.644444] [c0000000351f7b30] [c0000000002760f8] do_init_module (kernel/module/main.c:2543)
[ 2.644460] [c0000000351f7bb0] [c000000000278fe4] init_module_from_file (kernel/module/main.c:3199)
[ 2.644473] [c0000000351f7c90] [c0000000002793e0] sys_finit_module (kernel/module/main.c:3211 kernel/module/main.c:3238 kernel/module/main.c:3221)
[ 2.644487] [c0000000351f7da0] [c00000000002c084] system_call_exception (arch/powerpc/kernel/syscall.c:171)
[ 2.644500] [c0000000351f7e50] [c00000000000cb54] system_call_common (arch/powerpc/kernel/interrupt_64.S:292)
[ 2.644515] --- interrupt: c00 at 0x3fff8d653d8c
[ 2.644522] NIP: 00003fff8d653d8c LR: 00003fff8c9a4680 CTR: 0000000000000000
[ 2.644531] REGS: c0000000351f7e80 TRAP: 0c00 Not tainted (6.12.17-powerpc64 Debian 6.12.17-1)
[ 2.644541] MSR: 800000000200f032 <SF,VEC,EE,PR,FP,ME,IR,DR,RI> CR: 22222222 XER: 00000000
[ 2.644573] IRQMASK: 0
[ 2.644573] GPR00: 0000000000000161 00003fffebe8b640 00003fff8d757100 0000000000000052
[ 2.644573] GPR04: 00003fff8c9ac758 0000000000000004 0000000000000058 000000000000005a
[ 2.644573] GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
[ 2.644573] GPR12: 0000000000000000 00003fff8de947c0 0000000000000020 0000010037fcab20
[ 2.644573] GPR16: 0000000022222248 0000000000020000 0000000000000000 00003fffebe8bb80
[ 2.644573] GPR20: 0000000000000000 00003fffebe8bb70 0000000000000007 0000010037fca210
[ 2.644573] GPR24: 0000000000000000 0000000000000000 0000010037f6be40 0000000000000004
[ 2.644573] GPR28: 00003fff8c9ac758 0000000000020000 0000000000000004 0000010037fca210
[ 2.644698] NIP [00003fff8d653d8c] 0x3fff8d653d8c
[ 2.644705] LR [00003fff8c9a4680] 0x3fff8c9a4680
[ 2.644713] --- interrupt: c00
[ 2.644719] Code: 4182002c e92a0088 80690000 7c632038 7c632278 7c630034 5463d97e 786307e0 4e800020 60000000 60000000 e92a0020 <80690000> 4bffffd8 60000000 7ca50034
All code
========
0:* 41 82 00 2c beq 0x2c <-- trapping instruction
4: e9 2a 00 88 ld r9,136(r10)
8: 80 69 00 00 lwz r3,0(r9)
c: 7c 63 20 38 and r3,r3,r4
10: 7c 63 22 78 xor r3,r3,r4
14: 7c 63 00 34 cntlzw r3,r3
18: 54 63 d9 7e srwi r3,r3,5
1c: 78 63 07 e0 clrldi r3,r3,63
20: 4e 80 00 20 blr
24: 60 00 00 00 nop
28: 60 00 00 00 nop
2c: e9 2a 00 20 ld r9,32(r10)
30: 80 69 00 00 lwz r3,0(r9)
34: 4b ff ff d8 b 0xc
38: 60 00 00 00 nop
3c: 7c a5 00 34 cntlzw r5,r5
Code starting with the faulting instruction
===========================================
0: 80 69 00 00 lwz r3,0(r9)
4: 4b ff ff d8 b 0xffffffffffffffdc
8: 60 00 00 00 nop
c: 7c a5 00 34 cntlzw r5,r5
[ 2.644769] ---[ end trace 0000000000000000 ]---
(That's the bug splat from the bug report piped through
scripts/decode_stacktrace.sh)
The kernel has CONFIG_PCI_MSI_ARCH_FALLBACKS=y, so the first hunk
shouldn't change anything.
The disassembly of pci_msi_domain_supports in the kernel looks as
follows:
c000000000a394c0 <pci_msi_domain_supports>:
pci_msi_domain_supports():
debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:334
c000000000a394c0: 60 00 00 00 nop
c000000000a394c4: 60 00 00 00 nop
debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:353
c000000000a394c8: e9 43 02 e8 ld r10,744(r3)
c000000000a394cc: 2c 2a 00 00 cmpdi r10,0
c000000000a394d0: 41 82 00 50 beq c000000000a39520 <pci_msi_domain_supports+0x60>
irq_domain_is_hierarchy():
debian/build/build_powerpc_none_powerpc64/include/linux/irqdomain.h:661
c000000000a394d4: 81 2a 00 28 lwz r9,40(r10)
pci_msi_domain_supports():
debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:353 (discriminator 1)
c000000000a394d8: 71 28 00 01 andi. r8,r9,1
c000000000a394dc: 41 82 00 44 beq c000000000a39520 <pci_msi_domain_supports+0x60>
debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:359 (discriminator 1)
c000000000a394e0: 71 29 01 00 andi. r9,r9,256
c000000000a394e4: 41 82 00 2c beq c000000000a39510 <pci_msi_domain_supports+0x50>
debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:375
c000000000a394e8: e9 2a 00 88 ld r9,136(r10)
c000000000a394ec: 80 69 00 00 lwz r3,0(r9)
debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:378
c000000000a394f0: 7c 63 20 38 and r3,r3,r4
c000000000a394f4: 7c 63 22 78 xor r3,r3,r4
c000000000a394f8: 7c 63 00 34 cntlzw r3,r3
c000000000a394fc: 54 63 d9 7e srwi r3,r3,5
debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:379
c000000000a39500: 78 63 07 e0 clrldi r3,r3,63
c000000000a39504: 4e 80 00 20 blr
c000000000a39508: 60 00 00 00 nop
c000000000a3950c: 60 00 00 00 nop
debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:366
c000000000a39510: e9 2a 00 20 ld r9,32(r10)
c000000000a39514: 80 69 00 00 lwz r3,0(r9)
c000000000a39518: 4b ff ff d8 b c000000000a394f0 <pci_msi_domain_supports+0x30>
c000000000a3951c: 60 00 00 00 nop
debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:355
c000000000a39520: 7c a5 00 34 cntlzw r5,r5
c000000000a39524: 54 a3 d9 7e srwi r3,r5,5
debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:379
c000000000a39528: 78 63 07 e0 clrldi r3,r3,63
c000000000a3952c: 4e 80 00 20 blr
so the trapping happens in drivers/pci/msi/irqdomain.c:366 which is:
365 info = domain->host_data;
366 supported = info->flags;
According to the register dump domain == r10 == NULL, but then this code
would not have been reached and the faulting instruction would be at
c000000000a39510. So maybe it's only .host_data = NULL and the register
dump is unreliable??
The offsets match: .host_data is at offset 32 of struct
irq_domain and .flags is at offset 0 of struct msi_domain_info.
For more details see
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1127635 .
Does someone spot the issue?
Best regards
Uwe
On Wed, Mar 11 2026 at 12:22, Uwe Kleine-König wrote:
> this patch became a60b990798eb17433d0283788280422b1bd94b18 in v6.13-rc5
> and was backported to 6.12.y and 6.6.y (aed157301c65 and b1f7476e07b9
> respectively).
>
> A Debian user (Aaron, on Cc:) on powerpc has boot problems and bisected
> them to this commit. The relevant boot log of the failure is:
> [ 2.643879] BUG: Kernel NULL pointer dereference on read at 0x00000000
> [ 2.643891] Faulting instruction address: 0xc000000000a39514
> [ 2.643902] Oops: Kernel access of bad area, sig: 11 [#1]
> [ 2.643909] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
> [ 2.643920] Modules linked in: ohci_pci(+) ehci_hcd nvme_fabrics ohci_hcd nvme_keyring nvme_core usbcore nvme_auth scsi_transport_fc ipr configfs ehea(+) usb_common
> [ 2.643965] CPU: 5 UID: 0 PID: 250 Comm: (udev-worker) Not tainted 6.12.17-powerpc64 #1 Debian 6.12.17-1
> [ 2.643976] Hardware name: IBM,8204-E8A POWER6 (architected) 0x3e0302 0xf000002 of:IBM,EL350_118 hv:phyp pSeries
> [ 2.643986] NIP: c000000000a39514 LR: c000000000a36ed8 CTR: c000000000a35820
> [ 2.643995] REGS: c0000000351f6f60 TRAP: 0300 Not tainted (6.12.17-powerpc64 Debian 6.12.17-1)
> [ 2.644004] MSR: 8000000000009032 <SF,EE,ME,IR,DR,RI> CR: 24222288 XER: 00000000
> [ 2.644031] CFAR: c00000000000cfc4 DAR: 0000000000000000 DSISR: 40000000 IRQMASK: 0
> [ 2.644031] GPR00: c000000000a36ed8 c0000000351f7200 c00000000182e200 c0000003df294000
> [ 2.644031] GPR04: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> [ 2.644031] GPR08: 0000000000000001 0000000000000000 c00000000228fcc0 0000000044222288
> [ 2.644031] GPR12: c000000000a35820 c00000000eeacb00 0000000000000020 0000010037fcab20
> [ 2.644031] GPR16: 0000000022222248 0000000000020000 0000000000000000 00003fffebe8bb80
> [ 2.644031] GPR20: 0000000000000000 c00000000204db60 c00000000204dd60 c00000000b1ae780
> [ 2.644031] GPR24: 0000000000000000 00003fff8c9ac758 0000000000000000 c0000003df294000
> [ 2.644031] GPR28: 0000000000000001 0000000000000000 c0000003df294000 0000000000000001
> [ 2.644164] NIP [c000000000a39514] pci_msi_domain_supports (drivers/pci/msi/irqdomain.c:366)
> [ 2.644181] LR [c000000000a36ed8] __pci_enable_msi_range (drivers/pci/msi/msi.c:437)
> [ 2.644192] Call Trace:
> [ 2.644197] [c0000000351f7200] [c0000000351f7304] 0xc0000000351f7304 (unreliable)
> [ 2.644211] [c0000000351f7340] [c000000000a3578c] pci_alloc_irq_vectors_affinity (drivers/pci/msi/api.c:277)
> ========
> 0:* 41 82 00 2c beq 0x2c <-- trapping instruction
> 4: e9 2a 00 88 ld r9,136(r10)
> 8: 80 69 00 00 lwz r3,0(r9)
> c: 7c 63 20 38 and r3,r3,r4
> 10: 7c 63 22 78 xor r3,r3,r4
> 14: 7c 63 00 34 cntlzw r3,r3
> 18: 54 63 d9 7e srwi r3,r3,5
> 1c: 78 63 07 e0 clrldi r3,r3,63
> 20: 4e 80 00 20 blr
> 24: 60 00 00 00 nop
> 28: 60 00 00 00 nop
> 2c: e9 2a 00 20 ld r9,32(r10)
> 30: 80 69 00 00 lwz r3,0(r9)
> 34: 4b ff ff d8 b 0xc
> 38: 60 00 00 00 nop
> 3c: 7c a5 00 34 cntlzw r5,r5
>
> Code starting with the faulting instruction
> ===========================================
> 0: 80 69 00 00 lwz r3,0(r9)
> [ 2.644031] GPR08: 0000000000000001 0000000000000000 c00000000228fcc0 0000000044222288
So R9 is NULL, R10 is the domain pointer.
> 4: 4b ff ff d8 b 0xffffffffffffffdc
> 8: 60 00 00 00 nop
> c: 7c a5 00 34 cntlzw r5,r5
> [ 2.644769] ---[ end trace 0000000000000000 ]---
>
>
> (That's the bug splat from the bug report piped through
> scripts/decode_stacktrace.sh)
>
> The kernel has CONFIG_PCI_MSI_ARCH_FALLBACKS=y, so the first hunk
> shouldn't change anything.
Correct. But the Ooops is in the unchanged code part of
pci_msi_domain_supports().
> so the trapping happens in drivers/pci/msi/irqdomain.c:366 which is:
>
> 365 info = domain->host_data;
> 366 supported = info->flags;
>
> According to the register dump domain == r10 == NULL, but then this code
No. You are looking at the wrong register set. The second one is the
user space register set from the syscall entry.
R10 contains the domain pointer and R9 is NULL, which does not make any
sense.
On 6.12 power64 still uses the global PCI/MSI domain model. According to
the splat this is pseries so the global PCI/MSI domain is created in
__pseries_msi_allocate_domains() via pci_msi_create_irq_domain(). The
latter takes a pointer to
static struct msi_domain_info_pseries_msi_domain_info;
which is assigned to the global PCI/MSI domain::host_data.
Upstream got rid of that and uses per device domains, so it might have
been magically fixed by now, but I doubt it:
That new check in __pci_enable_msi_range() is benign as the actual
allocation code further down relies on domain::host_data being a valid
pointer as well.
It might not reach that point due to the subsequent checks, but if the
PCI device has pdev::dev::msi::domain populated, then this has to be
either a global PCI/MSI domain or a MSI parent domain. Both have
domain::host_data populated with a msi_domain_info pointer.
Something is mighty fishy here.
Aaron, can you please apply the patch below and see whether it fixes the
issue and provide the dmesg with the output of those pr_warn()'s?
The other information which would be useful: When you boot a kernel with
the commit reverted and look at that OHCI controller with lspci -vvv
then you should see whether it has MSI enabled or not. If it has MSI
enabled, then please provide the output of
/sys/kernel/debug/irq/irqs/$IRQNR
You need to enable CONFIG_GENERIC_IRQ_DEBUGFS for that.
And that's actually useful for the debug patch below too because you can
then look at the domain name output and gather more information from
/sys/kernel/debug/irq/domains/$NAME
Thanks,
tglx
---
drivers/pci/msi/irqdomain.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -115,6 +115,8 @@ struct irq_domain *pci_msi_create_irq_do
struct msi_domain_info *info,
struct irq_domain *parent)
{
+ struct irq_domain *domain;
+
if (WARN_ON(info->flags & MSI_FLAG_LEVEL_CAPABLE))
info->flags &= ~MSI_FLAG_LEVEL_CAPABLE;
@@ -135,7 +137,12 @@ struct irq_domain *pci_msi_create_irq_do
/* Let the core update the bus token */
info->bus_token = DOMAIN_BUS_PCI_MSI;
- return msi_create_irq_domain(fwnode, info, parent);
+ domain = msi_create_irq_domain(fwnode, info, parent);
+ if (domain) {
+ pr_warn("Created global PCI/MSI domain %lx %s flags: %x\n",
+ (unsigned long)domain, domain->name, domain->flags);
+ }
+ return domain;
}
EXPORT_SYMBOL_GPL(pci_msi_create_irq_domain);
@@ -356,6 +363,12 @@ bool pci_msi_domain_supports(struct pci_
return false;
}
+ if (!domain->host_data) {
+ pr_warn("Device MSI domain %lx %s %x lacks host data\n",
+ (unsigned long)domain, domain->name, domain->flags);
+ return false;
+ }
+
if (!irq_domain_is_msi_parent(domain)) {
/*
* For "global" PCI/MSI interrupt domains the associated
On 3/11/26 12:22, Uwe Kleine-König wrote:
> Control: forwarded -1 https://lore.kernel.org/lkml/abE_QoS5DM-ZltaV@monoceros
>
> #regzbot introduced: a60b990798eb17433d0283788280422b1bd94b18
Thomas, in case you missed it: this is a change of yours: a60b990798eb17
("PCI/MSI: Handle lack of irqdomain gracefully") [v6.13-rc5]
> #regzbot from: "Aaron D. Johnson" <debbugreporter@fnord.greeley.co.us>
> #regzbot monitor: https://bugs.debian.org/1127635
Thx for forwarding the regression. Nothing happened since then -- or am
I missing something? If so: is that okay for everybody, or should we do
anything about this?
BTW, did anyone check if this happens with mainline (6.13/7.0) as well
to rule out that this is something that only happenens in the stable
series it was backported too? If it's the latter I wonder if reverting
it there might be a easy way to resolve this.
Ciao, Thorsten
On 3/4/26 09:47, Alexander Stein wrote:
> On Sat, Dec 14, 2024 at 12:50:18PM +0100, Thomas Gleixner wrote:
>> Alexandre observed a warning emitted from pci_msi_setup_msi_irqs() on a
>> RISCV platform which does not provide PCI/MSI support:
>>
>> WARNING: CPU: 1 PID: 1 at drivers/pci/msi/msi.h:121 pci_msi_setup_msi_irqs+0x2c/0x32
>> __pci_enable_msix_range+0x30c/0x596
>> pci_msi_setup_msi_irqs+0x2c/0x32
>> pci_alloc_irq_vectors_affinity+0xb8/0xe2
>>
>> RISCV uses hierarchical interrupt domains and correctly does not implement
>> the legacy fallback. The warning triggers from the legacy fallback stub.
>>
>> That warning is bogus as the PCI/MSI layer knows whether a PCI/MSI parent
>> domain is associated with the device or not. There is a check for MSI-X,
>> which has a legacy assumption. But that legacy fallback assumption is only
>> valid when legacy support is enabled, but otherwise the check should simply
>> return -ENOTSUPP.
>>
>> Loongarch tripped over the same problem and blindly enabled legacy support
>> without implementing the legacy fallbacks. There are weak implementations
>> which return an error, so the problem was papered over.
>>
>> Correct pci_msi_domain_supports() to evaluate the legacy mode and add
>> the missing supported check into the MSI enable path to complete it.
>>
>> Fixes: d2a463b29741 ("PCI/MSI: Reject multi-MSI early")
>> Reported-by: Alexandre Ghiti <alexghiti@rivosinc.com>
>> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>> Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
>> Cc: stable@vger.kernel.org
>
> this patch became a60b990798eb17433d0283788280422b1bd94b18 in v6.13-rc5
> and was backported to 6.12.y and 6.6.y (aed157301c65 and b1f7476e07b9
> respectively).
>
> A Debian user (Aaron, on Cc:) on powerpc has boot problems and bisected
> them to this commit. The relevant boot log of the failure is:
>
> [ 2.643879] BUG: Kernel NULL pointer dereference on read at 0x00000000
> [ 2.643891] Faulting instruction address: 0xc000000000a39514
> [ 2.643902] Oops: Kernel access of bad area, sig: 11 [#1]
> [ 2.643909] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
> [ 2.643920] Modules linked in: ohci_pci(+) ehci_hcd nvme_fabrics ohci_hcd nvme_keyring nvme_core usbcore nvme_auth scsi_transport_fc ipr configfs ehea(+) usb_common
> [ 2.643965] CPU: 5 UID: 0 PID: 250 Comm: (udev-worker) Not tainted 6.12.17-powerpc64 #1 Debian 6.12.17-1
> [ 2.643976] Hardware name: IBM,8204-E8A POWER6 (architected) 0x3e0302 0xf000002 of:IBM,EL350_118 hv:phyp pSeries
> [ 2.643986] NIP: c000000000a39514 LR: c000000000a36ed8 CTR: c000000000a35820
> [ 2.643995] REGS: c0000000351f6f60 TRAP: 0300 Not tainted (6.12.17-powerpc64 Debian 6.12.17-1)
> [ 2.644004] MSR: 8000000000009032 <SF,EE,ME,IR,DR,RI> CR: 24222288 XER: 00000000
> [ 2.644031] CFAR: c00000000000cfc4 DAR: 0000000000000000 DSISR: 40000000 IRQMASK: 0
> [ 2.644031] GPR00: c000000000a36ed8 c0000000351f7200 c00000000182e200 c0000003df294000
> [ 2.644031] GPR04: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> [ 2.644031] GPR08: 0000000000000001 0000000000000000 c00000000228fcc0 0000000044222288
> [ 2.644031] GPR12: c000000000a35820 c00000000eeacb00 0000000000000020 0000010037fcab20
> [ 2.644031] GPR16: 0000000022222248 0000000000020000 0000000000000000 00003fffebe8bb80
> [ 2.644031] GPR20: 0000000000000000 c00000000204db60 c00000000204dd60 c00000000b1ae780
> [ 2.644031] GPR24: 0000000000000000 00003fff8c9ac758 0000000000000000 c0000003df294000
> [ 2.644031] GPR28: 0000000000000001 0000000000000000 c0000003df294000 0000000000000001
> [ 2.644164] NIP [c000000000a39514] pci_msi_domain_supports (drivers/pci/msi/irqdomain.c:366)
> [ 2.644181] LR [c000000000a36ed8] __pci_enable_msi_range (drivers/pci/msi/msi.c:437)
> [ 2.644192] Call Trace:
> [ 2.644197] [c0000000351f7200] [c0000000351f7304] 0xc0000000351f7304 (unreliable)
> [ 2.644211] [c0000000351f7340] [c000000000a3578c] pci_alloc_irq_vectors_affinity (drivers/pci/msi/api.c:277)
> [ 2.644225] [c0000000351f73d0] [c0003d0007d2f4d4] usb_hcd_pci_probe (drivers/usb/core/hcd-pci.c:192) usbcore
> [ 2.644246] [c0000000351f7470] [c0003d00084e6030] ohci_pci_probe (drivers/usb/host/ohci-pci.c:285) ohci_pci
> [ 2.644260] [c0000000351f7490] [c000000000a260e8] local_pci_probe (drivers/pci/pci-driver.c:324)
> [ 2.644274] [c0000000351f7510] [c000000000a26218] pci_call_probe (drivers/pci/pci-driver.c:392 (discriminator 1))
> [ 2.644287] [c0000000351f7670] [c000000000a27348] pci_device_probe (drivers/pci/pci-driver.c:452)
> [ 2.644300] [c0000000351f76b0] [c000000000b2e658] really_probe (drivers/base/dd.c:579 drivers/base/dd.c:658)
> [ 2.644314] [c0000000351f7740] [c000000000b2eb24] __driver_probe_device (drivers/base/dd.c:800)
> [ 2.644327] [c0000000351f77c0] [c000000000b2edc4] driver_probe_device (drivers/base/dd.c:831)
> [ 2.644340] [c0000000351f7800] [c000000000b2f188] __driver_attach (drivers/base/dd.c:1217)
> [ 2.644352] [c0000000351f7880] [c000000000b2ac64] bus_for_each_dev (drivers/base/bus.c:370)
> [ 2.644365] [c0000000351f78e0] [c000000000b2dac4] driver_attach (drivers/base/dd.c:1234)
> [ 2.644377] [c0000000351f7900] [c000000000b2cd98] bus_add_driver (drivers/base/bus.c:675)
> [ 2.644389] [c0000000351f7990] [c000000000b30ae4] driver_register (drivers/base/driver.c:246)
> [ 2.644402] [c0000000351f7a00] [c000000000a24f88] __pci_register_driver (drivers/pci/pci-driver.c:1450)
> [ 2.644415] [c0000000351f7a20] [c0003d00084e6800] ohci_pci_init (drivers/usb/host/ohci-pci.c:308) ohci_pci
> [ 2.644429] [c0000000351f7a50] [c00000000000fd60] do_one_initcall (init/main.c:1269)
> [ 2.644444] [c0000000351f7b30] [c0000000002760f8] do_init_module (kernel/module/main.c:2543)
> [ 2.644460] [c0000000351f7bb0] [c000000000278fe4] init_module_from_file (kernel/module/main.c:3199)
> [ 2.644473] [c0000000351f7c90] [c0000000002793e0] sys_finit_module (kernel/module/main.c:3211 kernel/module/main.c:3238 kernel/module/main.c:3221)
> [ 2.644487] [c0000000351f7da0] [c00000000002c084] system_call_exception (arch/powerpc/kernel/syscall.c:171)
> [ 2.644500] [c0000000351f7e50] [c00000000000cb54] system_call_common (arch/powerpc/kernel/interrupt_64.S:292)
> [ 2.644515] --- interrupt: c00 at 0x3fff8d653d8c
> [ 2.644522] NIP: 00003fff8d653d8c LR: 00003fff8c9a4680 CTR: 0000000000000000
> [ 2.644531] REGS: c0000000351f7e80 TRAP: 0c00 Not tainted (6.12.17-powerpc64 Debian 6.12.17-1)
> [ 2.644541] MSR: 800000000200f032 <SF,VEC,EE,PR,FP,ME,IR,DR,RI> CR: 22222222 XER: 00000000
> [ 2.644573] IRQMASK: 0
> [ 2.644573] GPR00: 0000000000000161 00003fffebe8b640 00003fff8d757100 0000000000000052
> [ 2.644573] GPR04: 00003fff8c9ac758 0000000000000004 0000000000000058 000000000000005a
> [ 2.644573] GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> [ 2.644573] GPR12: 0000000000000000 00003fff8de947c0 0000000000000020 0000010037fcab20
> [ 2.644573] GPR16: 0000000022222248 0000000000020000 0000000000000000 00003fffebe8bb80
> [ 2.644573] GPR20: 0000000000000000 00003fffebe8bb70 0000000000000007 0000010037fca210
> [ 2.644573] GPR24: 0000000000000000 0000000000000000 0000010037f6be40 0000000000000004
> [ 2.644573] GPR28: 00003fff8c9ac758 0000000000020000 0000000000000004 0000010037fca210
> [ 2.644698] NIP [00003fff8d653d8c] 0x3fff8d653d8c
> [ 2.644705] LR [00003fff8c9a4680] 0x3fff8c9a4680
> [ 2.644713] --- interrupt: c00
> [ 2.644719] Code: 4182002c e92a0088 80690000 7c632038 7c632278 7c630034 5463d97e 786307e0 4e800020 60000000 60000000 e92a0020 <80690000> 4bffffd8 60000000 7ca50034
> All code
> ========
> 0:* 41 82 00 2c beq 0x2c <-- trapping instruction
> 4: e9 2a 00 88 ld r9,136(r10)
> 8: 80 69 00 00 lwz r3,0(r9)
> c: 7c 63 20 38 and r3,r3,r4
> 10: 7c 63 22 78 xor r3,r3,r4
> 14: 7c 63 00 34 cntlzw r3,r3
> 18: 54 63 d9 7e srwi r3,r3,5
> 1c: 78 63 07 e0 clrldi r3,r3,63
> 20: 4e 80 00 20 blr
> 24: 60 00 00 00 nop
> 28: 60 00 00 00 nop
> 2c: e9 2a 00 20 ld r9,32(r10)
> 30: 80 69 00 00 lwz r3,0(r9)
> 34: 4b ff ff d8 b 0xc
> 38: 60 00 00 00 nop
> 3c: 7c a5 00 34 cntlzw r5,r5
>
> Code starting with the faulting instruction
> ===========================================
> 0: 80 69 00 00 lwz r3,0(r9)
> 4: 4b ff ff d8 b 0xffffffffffffffdc
> 8: 60 00 00 00 nop
> c: 7c a5 00 34 cntlzw r5,r5
> [ 2.644769] ---[ end trace 0000000000000000 ]---
>
>
> (That's the bug splat from the bug report piped through
> scripts/decode_stacktrace.sh)
>
> The kernel has CONFIG_PCI_MSI_ARCH_FALLBACKS=y, so the first hunk
> shouldn't change anything.
>
> The disassembly of pci_msi_domain_supports in the kernel looks as
> follows:
>
> c000000000a394c0 <pci_msi_domain_supports>:
> pci_msi_domain_supports():
> debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:334
> c000000000a394c0: 60 00 00 00 nop
> c000000000a394c4: 60 00 00 00 nop
> debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:353
> c000000000a394c8: e9 43 02 e8 ld r10,744(r3)
> c000000000a394cc: 2c 2a 00 00 cmpdi r10,0
> c000000000a394d0: 41 82 00 50 beq c000000000a39520 <pci_msi_domain_supports+0x60>
> irq_domain_is_hierarchy():
> debian/build/build_powerpc_none_powerpc64/include/linux/irqdomain.h:661
> c000000000a394d4: 81 2a 00 28 lwz r9,40(r10)
> pci_msi_domain_supports():
> debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:353 (discriminator 1)
> c000000000a394d8: 71 28 00 01 andi. r8,r9,1
> c000000000a394dc: 41 82 00 44 beq c000000000a39520 <pci_msi_domain_supports+0x60>
> debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:359 (discriminator 1)
> c000000000a394e0: 71 29 01 00 andi. r9,r9,256
> c000000000a394e4: 41 82 00 2c beq c000000000a39510 <pci_msi_domain_supports+0x50>
> debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:375
> c000000000a394e8: e9 2a 00 88 ld r9,136(r10)
> c000000000a394ec: 80 69 00 00 lwz r3,0(r9)
> debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:378
> c000000000a394f0: 7c 63 20 38 and r3,r3,r4
> c000000000a394f4: 7c 63 22 78 xor r3,r3,r4
> c000000000a394f8: 7c 63 00 34 cntlzw r3,r3
> c000000000a394fc: 54 63 d9 7e srwi r3,r3,5
> debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:379
> c000000000a39500: 78 63 07 e0 clrldi r3,r3,63
> c000000000a39504: 4e 80 00 20 blr
> c000000000a39508: 60 00 00 00 nop
> c000000000a3950c: 60 00 00 00 nop
> debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:366
> c000000000a39510: e9 2a 00 20 ld r9,32(r10)
> c000000000a39514: 80 69 00 00 lwz r3,0(r9)
> c000000000a39518: 4b ff ff d8 b c000000000a394f0 <pci_msi_domain_supports+0x30>
> c000000000a3951c: 60 00 00 00 nop
> debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:355
> c000000000a39520: 7c a5 00 34 cntlzw r5,r5
> c000000000a39524: 54 a3 d9 7e srwi r3,r5,5
> debian/build/build_powerpc_none_powerpc64/drivers/pci/msi/irqdomain.c:379
> c000000000a39528: 78 63 07 e0 clrldi r3,r3,63
> c000000000a3952c: 4e 80 00 20 blr
>
>
> so the trapping happens in drivers/pci/msi/irqdomain.c:366 which is:
>
> 365 info = domain->host_data;
> 366 supported = info->flags;
>
> According to the register dump domain == r10 == NULL, but then this code
> would not have been reached and the faulting instruction would be at
> c000000000a39510. So maybe it's only .host_data = NULL and the register
> dump is unreliable??
>
> The offsets match: .host_data is at offset 32 of struct
> irq_domain and .flags is at offset 0 of struct msi_domain_info.
>
> For more details see
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1127635 .
>
> Does someone spot the issue?
>
> Best regards
> Uwe
On Wed, Apr 22 2026 at 10:50, Thorsten Leemhuis wrote:
> On 3/11/26 12:22, Uwe Kleine-König wrote:
>> Control: forwarded -1 https://lore.kernel.org/lkml/abE_QoS5DM-ZltaV@monoceros
>>
>> #regzbot introduced: a60b990798eb17433d0283788280422b1bd94b18
>
> Thomas, in case you missed it: this is a change of yours: a60b990798eb17
> ("PCI/MSI: Handle lack of irqdomain gracefully") [v6.13-rc5]
Yes. That fell through the cracks.
>> #regzbot from: "Aaron D. Johnson" <debbugreporter@fnord.greeley.co.us>
>> #regzbot monitor: https://bugs.debian.org/1127635
>
> Thx for forwarding the regression. Nothing happened since then -- or am
> I missing something? If so: is that okay for everybody, or should we do
> anything about this?
>
> BTW, did anyone check if this happens with mainline (6.13/7.0) as well
> to rule out that this is something that only happenens in the stable
> series it was backported too? If it's the latter I wonder if reverting
> it there might be a easy way to resolve this.
Let me have a look.
The following commit has been merged into the irq/urgent branch of tip:
Commit-ID: a60b990798eb17433d0283788280422b1bd94b18
Gitweb: https://git.kernel.org/tip/a60b990798eb17433d0283788280422b1bd94b18
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Sat, 14 Dec 2024 12:50:18 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Dec 2024 10:59:47 +01:00
PCI/MSI: Handle lack of irqdomain gracefully
Alexandre observed a warning emitted from pci_msi_setup_msi_irqs() on a
RISCV platform which does not provide PCI/MSI support:
WARNING: CPU: 1 PID: 1 at drivers/pci/msi/msi.h:121 pci_msi_setup_msi_irqs+0x2c/0x32
__pci_enable_msix_range+0x30c/0x596
pci_msi_setup_msi_irqs+0x2c/0x32
pci_alloc_irq_vectors_affinity+0xb8/0xe2
RISCV uses hierarchical interrupt domains and correctly does not implement
the legacy fallback. The warning triggers from the legacy fallback stub.
That warning is bogus as the PCI/MSI layer knows whether a PCI/MSI parent
domain is associated with the device or not. There is a check for MSI-X,
which has a legacy assumption. But that legacy fallback assumption is only
valid when legacy support is enabled, but otherwise the check should simply
return -ENOTSUPP.
Loongarch tripped over the same problem and blindly enabled legacy support
without implementing the legacy fallbacks. There are weak implementations
which return an error, so the problem was papered over.
Correct pci_msi_domain_supports() to evaluate the legacy mode and add
the missing supported check into the MSI enable path to complete it.
Fixes: d2a463b29741 ("PCI/MSI: Reject multi-MSI early")
Reported-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/87ed2a8ow5.ffs@tglx
---
drivers/pci/msi/irqdomain.c | 7 +++++--
drivers/pci/msi/msi.c | 4 ++++
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index 5691257..d7ba879 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -350,8 +350,11 @@ bool pci_msi_domain_supports(struct pci_dev *pdev, unsigned int feature_mask,
domain = dev_get_msi_domain(&pdev->dev);
- if (!domain || !irq_domain_is_hierarchy(domain))
- return mode == ALLOW_LEGACY;
+ if (!domain || !irq_domain_is_hierarchy(domain)) {
+ if (IS_ENABLED(CONFIG_PCI_MSI_ARCH_FALLBACKS))
+ return mode == ALLOW_LEGACY;
+ return false;
+ }
if (!irq_domain_is_msi_parent(domain)) {
/*
diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
index 3a45879..2f647ca 100644
--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -433,6 +433,10 @@ int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
if (WARN_ON_ONCE(dev->msi_enabled))
return -EINVAL;
+ /* Test for the availability of MSI support */
+ if (!pci_msi_domain_supports(dev, 0, ALLOW_LEGACY))
+ return -ENOTSUPP;
+
nvec = pci_msi_vec_count(dev);
if (nvec < 0)
return nvec;© 2016 - 2026 Red Hat, Inc.