[RFC PATCH] riscv: Fix PCI warning by enabling PCI_MSI_ARCH_FALLBACKS

[RFC PATCH] riscv: Fix PCI warning by enabling PCI_MSI_ARCH_FALLBACKS

[Alexandre Ghiti]

When the interrupt controller is not using the IMSIC and ACPI is enabled,
the following warning appears:

[    0.866401] WARNING: CPU: 1 PID: 1 at drivers/pci/msi/msi.h:121 pci_msi_setup_msi_irqs+0x2c/0x32
[    0.867071] Modules linked in:
[    0.867389] CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.13.0-rc2-00001-g795582ce7e24-dirty #44
[    0.867538] Hardware name: QEMU QEMU Virtual Machine, BIOS
[    0.867672] epc : pci_msi_setup_msi_irqs+0x2c/0x32
[    0.867738]  ra : __pci_enable_msix_range+0x30c/0x596
[    0.867783] epc : ffffffff8050af80 ra : ffffffff8050a66e sp : ff20000000023750
[    0.867809]  gp : ffffffff815153b0 tp : ff60000080108000 t0 : ff60000081109600
[    0.867833]  t1 : 0000000000000228 t2 : 0000000000000004 s0 : ff20000000023860
[    0.867857]  s1 : ff60000080de1000 a0 : ff60000080de1000 a1 : 0000000000000005
[    0.867880]  a2 : 0000000000000011 a3 : 0000000000000000 a4 : 0000000000000000
[    0.867902]  a5 : 0000000000000000 a6 : ff600000806368f0 a7 : fffffffffffffff0
[    0.867925]  s2 : 0000000000000005 s3 : ffffffffffffffff s4 : 0000000000000000
[    0.867948]  s5 : ff60000080de10c0 s6 : 0000000000000005 s7 : 0000000000000005
[    0.867970]  s8 : ff20000000023a08 s9 : ff600000811093c0 s10: 000000000000002c
[    0.867993]  s11: ff60000081109410 t3 : 0000000000000001 t4 : ff600000803a2878
[    0.868014]  t5 : 0000000000000004 t6 : ff60000080357450
[    0.868036] status: 0000000200000120 badaddr: ffffffff8050af80 cause: 0000000000000003
[    0.868186] [<ffffffff8050af80>] pci_msi_setup_msi_irqs+0x2c/0x32
[    0.868339] [<ffffffff80509172>] pci_alloc_irq_vectors_affinity+0xb8/0xe2
[    0.868362] [<ffffffff8059d62c>] vp_find_vqs_msix+0x12a/0x370
[    0.868385] [<ffffffff8059d8a0>] vp_find_vqs+0x2e/0x1de
[    0.868402] [<ffffffff8059bd80>] vp_modern_find_vqs+0x12/0x4e
[    0.868425] [<ffffffff80624a50>] init_vq+0x2b4/0x336
[    0.868448] [<ffffffff80624c36>] virtblk_probe+0xd4/0x90e
[    0.868469] [<ffffffff80594e02>] virtio_dev_probe+0x14a/0x1e6
[    0.868488] [<ffffffff805fe04c>] really_probe+0x86/0x234
[    0.868509] [<ffffffff805fe256>] __driver_probe_device+0x5c/0xda
[    0.868529] [<ffffffff805fe392>] driver_probe_device+0x2c/0xb2
[    0.868549] [<ffffffff805fe512>] __driver_attach+0x6c/0x11a
[    0.868569] [<ffffffff805fc17e>] bus_for_each_dev+0x60/0xae
[    0.868588] [<ffffffff805fda7c>] driver_attach+0x1a/0x22
[    0.868607] [<ffffffff805fd398>] bus_add_driver+0xce/0x1d6
[    0.868627] [<ffffffff805ff0b2>] driver_register+0x3e/0xd8
[    0.868647] [<ffffffff80594614>] __register_virtio_driver+0x1e/0x2c
[    0.868694] [<ffffffff80a31b82>] virtio_blk_init+0x6a/0x9e
[    0.868733] [<ffffffff8000f128>] do_one_initcall+0x58/0x194
[    0.868755] [<ffffffff80a011b0>] kernel_init_freeable+0x224/0x28e
[    0.868775] [<ffffffff809e4e48>] kernel_init+0x1e/0x13a
[    0.868795] [<ffffffff809ed952>] ret_from_fork+0xe/0x18

So enable PCI_MSI_ARCH_FALLBACKS to get rid of this.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---

This is an RFC as I'm really not sure this is the right fix,
Anup/Sunil/Thomas if you have any idea, please step in! Thanks

 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d4a7ca0388c0..40d51feac2bb 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -199,6 +199,7 @@ config RISCV
 	select PCI_DOMAINS_GENERIC if PCI
 	select PCI_ECAM if (ACPI && PCI)
 	select PCI_MSI if PCI
+	select PCI_MSI_ARCH_FALLBACKS if PCI
 	select RISCV_ALTERNATIVE if !XIP_KERNEL
 	select RISCV_APLIC
 	select RISCV_IMSIC
-- 
2.39.2

Re: [RFC PATCH] riscv: Fix PCI warning by enabling PCI_MSI_ARCH_FALLBACKS

[Thomas Gleixner]

On Fri, Dec 13 2024 at 12:57, Alexandre Ghiti wrote:
> When the interrupt controller is not using the IMSIC and ACPI is enabled,
> the following warning appears:
>
> [    0.866401] WARNING: CPU: 1 PID: 1 at drivers/pci/msi/msi.h:121 pci_msi_setup_msi_irqs+0x2c/0x32
> [    0.867071] Modules linked in:
> [    0.867389] CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.13.0-rc2-00001-g795582ce7e24-dirty #44
> [    0.867538] Hardware name: QEMU QEMU Virtual Machine, BIOS
> [    0.867672] epc : pci_msi_setup_msi_irqs+0x2c/0x32
> [    0.867738]  ra : __pci_enable_msix_range+0x30c/0x596

Removing a ton of badly formatted stack trace:

https://www.kernel.org/doc/html/latest/process/submitting-patches.html#backtraces-in-commit-messages

>
> So enable PCI_MSI_ARCH_FALLBACKS to get rid of this.

No. PCI_MSI_ARCH_FALLBACKS is really only meant for architectures which
implement the legacy fallbacks and not to paper over the underlying
logic bug in the pci/msi code. Of course the loongson folks ran into the
same problem two years ago and went for the sloppy fix without talking
to anyone...

Thanks for bringing it up instead of silently slapping it into the RISCV
tree !

The uncompiled patch below should fix this for real.

Thanks,

        tglx
---
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -185,7 +185,6 @@ config LOONGARCH
 	select PCI_DOMAINS_GENERIC
 	select PCI_ECAM if ACPI
 	select PCI_LOONGSON
-	select PCI_MSI_ARCH_FALLBACKS
 	select PCI_QUIRKS
 	select PERF_USE_VMALLOC
 	select RTC_LIB
--- 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
@@ -442,6 +442,10 @@ int __pci_enable_msi_range(struct pci_de
 	if (nvec > maxvec)
 		nvec = maxvec;
 
+	/* Test for the availability of MSI support */
+	if (!pci_msi_domain_supports(dev, 0, ALLOW_LEGACY))
+		return -ENOTSUPP;
+
 	rc = pci_setup_msi_context(dev);
 	if (rc)
 		return rc;

Re: [RFC PATCH] riscv: Fix PCI warning by enabling PCI_MSI_ARCH_FALLBACKS

[Alexandre Ghiti]

Hi Thomas,

On Fri, Dec 13, 2024 at 2:12 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> On Fri, Dec 13 2024 at 12:57, Alexandre Ghiti wrote:
> > When the interrupt controller is not using the IMSIC and ACPI is enabled,
> > the following warning appears:
> >
> > [    0.866401] WARNING: CPU: 1 PID: 1 at drivers/pci/msi/msi.h:121 pci_msi_setup_msi_irqs+0x2c/0x32
> > [    0.867071] Modules linked in:
> > [    0.867389] CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.13.0-rc2-00001-g795582ce7e24-dirty #44
> > [    0.867538] Hardware name: QEMU QEMU Virtual Machine, BIOS
> > [    0.867672] epc : pci_msi_setup_msi_irqs+0x2c/0x32
> > [    0.867738]  ra : __pci_enable_msix_range+0x30c/0x596
>
> Removing a ton of badly formatted stack trace:
>
> https://www.kernel.org/doc/html/latest/process/submitting-patches.html#backtraces-in-commit-messages

Thanks for the pointer.

>
> >
> > So enable PCI_MSI_ARCH_FALLBACKS to get rid of this.
>
> No. PCI_MSI_ARCH_FALLBACKS is really only meant for architectures which
> implement the legacy fallbacks and not to paper over the underlying
> logic bug in the pci/msi code. Of course the loongson folks ran into the
> same problem two years ago and went for the sloppy fix without talking
> to anyone...
>
> Thanks for bringing it up instead of silently slapping it into the RISCV
> tree !
>
> The uncompiled patch below should fix this for real.

It does, when applied the warning disappears (on riscv at least). You can add:

Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com> # riscv

Thanks for your quick answer!

Alex

>
> Thanks,
>
>         tglx
> ---
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -185,7 +185,6 @@ config LOONGARCH
>         select PCI_DOMAINS_GENERIC
>         select PCI_ECAM if ACPI
>         select PCI_LOONGSON
> -       select PCI_MSI_ARCH_FALLBACKS
>         select PCI_QUIRKS
>         select PERF_USE_VMALLOC
>         select RTC_LIB
> --- 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
> @@ -442,6 +442,10 @@ int __pci_enable_msi_range(struct pci_de
>         if (nvec > maxvec)
>                 nvec = maxvec;
>
> +       /* Test for the availability of MSI support */
> +       if (!pci_msi_domain_supports(dev, 0, ALLOW_LEGACY))
> +               return -ENOTSUPP;
> +
>         rc = pci_setup_msi_context(dev);
>         if (rc)
>                 return rc;

[Patch] PCI/MSI: Handle lack of irqdomain gracefully

[Thomas Gleixner]

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;

[tip: irq/urgent] PCI/MSI: Handle lack of irqdomain gracefully

[tip-bot2 for Thomas Gleixner]

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;

Re: [Patch] PCI/MSI: Handle lack of irqdomain gracefully

[patchwork-bot+linux-riscv]

Hello:

This patch was applied to riscv/linux.git (fixes)
by Thomas Gleixner <tglx@linutronix.de>:

On Sat, 14 Dec 2024 12:50:18 +0100 you 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
> 
> [...]

Here is the summary with links:
  - PCI/MSI: Handle lack of irqdomain gracefully
    https://git.kernel.org/riscv/c/a60b990798eb

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [Patch] PCI/MSI: Handle lack of irqdomain gracefully

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 12425 bytes --]

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

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