Date:	Tue, 16 Apr 2013 18:08:08 -0400
From:	Don Dutile <ddutile@...hat.com>
To:	Neil Horman <nhorman@...driver.com>
CC:	linux-kernel@...r.kernel.org, Prarit Bhargava <prarit@...hat.com>,
	Don Zickus <dzickus@...hat.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Asit Mallick <asit.k.mallick@...el.com>,
	David Woodhouse <dwmw2@...radead.org>,
	linux-pci@...r.kernel.org, Joerg Roedel <joro@...tes.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Arkadiusz Miśkiewicz 
	<arekm@...en.pl>
Subject: Re: [PATCH v10] irq: add quirk for broken interrupt remapping on
 55XX chipsets

On 04/16/2013 04:38 PM, Neil Horman 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@...driver.com>
> CC: Prarit Bhargava<prarit@...hat.com>
> CC: Don Zickus<dzickus@...hat.com>
> CC: Don Dutile<ddutile@...hat.com>
> CC: Bjorn Helgaas<bhelgaas@...gle.com>
> CC: Asit Mallick<asit.k.mallick@...el.com>
> CC: David Woodhouse<dwmw2@...radead.org>
> CC: linux-pci@...r.kernel.org
> CC: Joerg Roedel<joro@...tes.org>
> CC: Konrad Rzeszutek Wilk<konrad.wilk@...cle.com>
> CC: Arkadiusz Miśkiewicz<arekm@...en.pl>
> ---
>
> 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
>
> v8)
>
> * Removed extraneous code from irq_remapping_enabled
>
> v9)
>
> * Fix stupid build break from rushing to shuffle simmilar header files about
>    Thanks to Arkadiusz Miśkiewicz  for pointing it out
>
> v10)
>
> * Rewrite to hide the irq_remap_broken variable so we don't need to pull in a
>    private header file
/me waiting for v11...
/me runs! ;-)

Neil,
Looks good, and kudos on your tenacity through all the revs.
- Don(Dutile)

> ---
>   arch/x86/include/asm/irq_remapping.h |  1 +
>   arch/x86/kernel/early-quirks.c       | 26 ++++++++++++++++++++++++++
>   drivers/iommu/intel_irq_remapping.c  | 10 ++++++++++
>   drivers/iommu/irq_remapping.c        |  6 ++++++
>   drivers/iommu/irq_remapping.h        |  2 ++
>   5 files changed, 45 insertions(+)
>
> diff --git a/arch/x86/include/asm/irq_remapping.h b/arch/x86/include/asm/irq_remapping.h
> index 95fd352..d740cb4 100644
> --- a/arch/x86/include/asm/irq_remapping.h
> +++ b/arch/x86/include/asm/irq_remapping.h
> @@ -28,6 +28,7 @@
>
>   extern void setup_irq_remapping_ops(void);
>   extern int irq_remapping_supported(void);
> +extern void set_irq_remapping_broken(void);
>   extern int irq_remapping_prepare(void);
>   extern int irq_remapping_enable(void);
>   extern void irq_remapping_disable(void);
> diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
> index 3755ef4..589092d 100644
> --- a/arch/x86/kernel/early-quirks.c
> +++ b/arch/x86/kernel/early-quirks.c
> @@ -18,6 +18,7 @@
>   #include<asm/apic.h>
>   #include<asm/iommu.h>
>   #include<asm/gart.h>
> +#include<asm/irq_remapping.h>
>
>   static void __init fix_hypertransport_config(int num, int slot, int func)
>   {
> @@ -192,6 +193,27 @@ 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 = read_pci_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)
> +		set_irq_remapping_broken();
> +
> +}
> +#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 +243,10 @@ 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..3c11043 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;
>
> @@ -211,6 +212,11 @@ void __init setup_irq_remapping_ops(void)
>   #endif
>   }
>
> +void set_irq_remapping_broken(void)
> +{
> +	irq_remap_broken = 1;
> +}
> +
>   int irq_remapping_supported(void)
>   {
>   	if (disable_irq_remap)
> diff --git a/drivers/iommu/irq_remapping.h b/drivers/iommu/irq_remapping.h
> index ecb6376..90c4dae 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;
> @@ -89,6 +90,7 @@ extern struct irq_remap_ops amd_iommu_irq_ops;
>
>   #define irq_remapping_enabled 0
>   #define disable_irq_remap     1
> +#define irq_remap_broken      0
>
>   #endif /* CONFIG_IRQ_REMAP */
>

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