Re: [PATCH v7] irq: add quirk for broken interrupt remapping on 55XX chipsets

From: Bjorn Helgaas
Date: Mon Apr 15 2013 - 11:31:04 EST


On Mon, Apr 15, 2013 at 5:18 AM, Neil Horman <nhorman@xxxxxxxxxxxxx> wrote:
> A few years back intel published a spec update:
> http://www.intel.com/content/dam/doc/specification-update/5520-and-5500-chipset-ioh-specification-update.pdf
>
> For the 5520 and 5500 chipsets which contained an errata (specificially errata
> 53), which noted that these chipsets can't properly do interrupt remapping, and
> as a result the recommend that interrupt remapping be disabled in bios. While
> many vendors have a bios update to do exactly that, not all do, and of course
> not all users update their bios to a level that corrects the problem. As a
> result, occasionally interrupts can arrive at a cpu even after affinity for that
> interrupt has be moved, leading to lost or spurrious interrupts (usually
> characterized by the message:
> kernel: do_IRQ: 7.71 No irq handler for vector (irq -1)
>
> There have been several incidents recently of people seeing this error, and
> investigation has shown that they have system for which their BIOS level is such
> that this feature was not properly turned off. As such, it would be good to
> give them a reminder that their systems are vulnurable to this problem. For
> details of those that reported the problem, please see:
> https://bugzilla.redhat.com/show_bug.cgi?id=887006
>
> Signed-off-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
> CC: Prarit Bhargava <prarit@xxxxxxxxxx>
> CC: Don Zickus <dzickus@xxxxxxxxxx>
> CC: Don Dutile <ddutile@xxxxxxxxxx>
> CC: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> CC: Asit Mallick <asit.k.mallick@xxxxxxxxx>
> CC: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
> CC: linux-pci@xxxxxxxxxxxxxxx
> CC: Joerg Roedel <joro@xxxxxxxxxx>
> CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>
> Change notes:
>
> v2)
>
> * Moved the quirk to the x86 arch, since consensus seems to be that the 55XX
> chipset series is x86 only. I decided however to keep the quirk as a regular
> quirk, not an early_quirk. Early quirks have no way currently to determine if
> BIOS has properly disabled the feature in the iommu, at least not without
> significant hacking, and since its quite possible this will be a short lived
> quirk, should Don Z's workaround code prove successful (and it looks like it may
> well), I don't think that necessecary.
>
> * Removed the WARNING banner from the quirk, and added the HW_ERR token to the
> string, I opted to leave the newlines in place however, as I really couldnt
> find a way to keep the text on a single line is still legible from a code
> perspective. I think theres enough language in there that using cscope on just
> about any substring however will turn it up, and again, this may be a short
> lived quirk.
>
> v3)
>
> * Removed defines from pci_ids.h, and used direct id values as per request from
> Bjorn.
>
> v4)
>
> * Converted pr_warn to WARN_TAINT(TAINT_FIRMWARE_WORKAROUND) as per David
> Woodhouse
>
> v5)
>
> * Moved check to an early quirk, and flagged the broken chip, so we could
> reasonably disable irq remapping during bootup.
>
> v6)
>
> * Clean up of stupid extra thrash in quirks.c
>
> v7)
>
> * Move broken check to intel_irq_remapping.c
> * Fixed another typo
> * Finally made the reference bugzilla public
> ---
> arch/x86/kernel/early-quirks.c | 25 +++++++++++++++++++++++++
> drivers/iommu/intel_irq_remapping.c | 10 ++++++++++
> drivers/iommu/irq_remapping.c | 12 ++++++++++++
> drivers/iommu/irq_remapping.h | 1 +
> 4 files changed, 48 insertions(+)
>
> diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
> index 3755ef4..bfa3139 100644
> --- a/arch/x86/kernel/early-quirks.c
> +++ b/arch/x86/kernel/early-quirks.c
> @@ -192,6 +192,27 @@ static void __init ati_bugs_contd(int num, int slot, int func)
> }
> #endif
>
> +#ifdef CONFIG_IRQ_REMAP
> +static void __init intel_remapping_check(int num, int slot, int func)
> +{
> + u8 revision;
> +
> + revision = pci_read_config_byte(num, slot, func , PCI_REVISION_ID);
> +
> + /*
> + * Revision 0x13 of this chipset supports irq remapping
> + * but has an erratum that breaks its behavior, flag it as such
> + */
> + if (revision == 0x13)
> + irq_remap_broken = 1;
> +
> +}
> +#else
> +static void __init intel_remapping_check(int num, int slot, int func)
> +{
> +}
> +#endif
> +
> #define QFLAG_APPLY_ONCE 0x1
> #define QFLAG_APPLIED 0x2
> #define QFLAG_DONE (QFLAG_APPLY_ONCE|QFLAG_APPLIED)
> @@ -221,6 +242,10 @@ static struct chipset early_qrk[] __initdata = {
> PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_bugs },
> { PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS,
> PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_bugs_contd },
> + { PCI_VENDOR_ID_INTEL, 0x3403, PCI_CLASS_BRIDGE_HOST,
> + PCI_BASE_CLASS_BRIDGE, 0, intel_remapping_check },
> + { PCI_VENDOR_ID_INTEL, 0x3406, PCI_CLASS_BRIDGE_HOST,
> + PCI_BASE_CLASS_BRIDGE, 0, intel_remapping_check },
> {}
> };
>
> diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
> index f3b8f23..5b19b2d 100644
> --- a/drivers/iommu/intel_irq_remapping.c
> +++ b/drivers/iommu/intel_irq_remapping.c
> @@ -524,6 +524,16 @@ static int __init intel_irq_remapping_supported(void)
>
> if (disable_irq_remap)
> return 0;
> + if (irq_remap_broken) {
> + WARN_TAINT(1, TAINT_FIRMWARE_WORKAROUND,
> + "This system BIOS has enabled interrupt remapping\n"
> + "on a chipset that contains an erratum making that\n"
> + "feature unstable. To maintain system stability\n"
> + "interrupt remapping is being disabled. Please\n"
> + "contact your BIOS vendor for an update\n");
> + disable_irq_remap = 1;
> + return 0;
> + }
>
> if (!dmar_ir_support())
> return 0;
> diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
> index d56f8c1..2b56e92 100644
> --- a/drivers/iommu/irq_remapping.c
> +++ b/drivers/iommu/irq_remapping.c
> @@ -19,6 +19,7 @@
> int irq_remapping_enabled;
>
> int disable_irq_remap;
> +int irq_remap_broken;
> int disable_sourceid_checking;
> int no_x2apic_optout;
>
> @@ -216,6 +217,17 @@ int irq_remapping_supported(void)
> if (disable_irq_remap)
> return 0;
>
> + if (irq_remap_broken) {
> + WARN_TAINT(1, TAIN_FIRMWARE_WORKAROUND,
> + "This system BIOS has enabled interrupt remapping\n"
> + "on a chipset that contains an erratum making that\n"
> + "feature unstable. Please reboot with nointremap\n"
> + "added to the kernel command line and contact\n"
> + "your BIOS vendor for an update");
> + disable_irq_remap = 1;
> + return 0;
> + }
> +

I think you probably intended to drop the change to this file, since
you moved it to intel_irq_remapping.c. If you did intend to keep it,
s/TAIN_/TAINT_/.

> if (!remap_ops || !remap_ops->supported)
> return 0;
>
> diff --git a/drivers/iommu/irq_remapping.h b/drivers/iommu/irq_remapping.h
> index ecb6376..d7537e4 100644
> --- a/drivers/iommu/irq_remapping.h
> +++ b/drivers/iommu/irq_remapping.h
> @@ -32,6 +32,7 @@ struct pci_dev;
> struct msi_msg;
>
> extern int disable_irq_remap;
> +extern int irq_remap_broken;
> extern int disable_sourceid_checking;
> extern int no_x2apic_optout;
> extern int irq_remapping_enabled;
> --
> 1.8.1.4
>
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