linux-kernel - Re: [RFC PATCH] riscv: Fix PCI warning by enabling PCI_MSI_ARCH

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAHVXubiNMp9chdUdvYjiQC2LMhNMMaGEiLMWZ-4RSV54jakP3g@mail.gmail.com>
Date: Fri, 13 Dec 2024 14:51:55 +0100
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Anup Patel <anup@...infault.org>, Sunil V L <sunilvl@...tanamicro.com>, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] riscv: Fix PCI warning by enabling PCI_MSI_ARCH_FALLBACKS

Hi Thomas,

On Fri, Dec 13, 2024 at 2:12 PM Thomas Gleixner <tglx@...utronix.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@...osinc.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;