linux-kernel - Re: Info: mapping multiple BARs. Your kernel is fine.

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Message-ID: <20140417104533.GB8215@pd.tnic>
Date:	Thu, 17 Apr 2014 12:45:33 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Dave Jones <davej@...hat.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"Zhang, Rui" <rui.zhang@...el.com>,
	"Lu, Aaron" <aaron.lu@...el.com>,
	lkml <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Yinghai Lu <yinghai@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Stephane Eranian <eranian@...gle.com>,
	"Yan, Zheng Z" <zheng.z.yan@...el.com>
Subject: Re: Info: mapping multiple BARs. Your kernel is fine.

Hi Bjorn,

thanks for the patch, a couple of notes below:

On Wed, Apr 16, 2014 at 04:56:00PM -0600, Bjorn Helgaas wrote:
> PNP: Work around Haswell BIOS defect in MCH area reporting
> 
> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> Work around a Haswell BIOS defect that causes part of the MCH area to be
> unreported.

Yep, what Stephane said, this is not HSW only.

> MCHBAR is not an architected PCI BAR, so MCH space is usually reported as a
> PNP0C02 resource.  The MCH space was 16KB prior to Haswell, but it is 32KB
> in Haswell.  Some Haswell BIOSes still report a PNP0C02 resource that is
> only 16KB, which means the rest of the MCH space is consumed but
> unreported.
> 
> This can cause resource map sanity check warnings or (theoretically) a
> device conflict if we assigned the unreported space to another device.
> 
> The Intel perf event uncore driver tripped over this when it claimed the
> MCH region:
> 
>   resource map sanity check conflict: 0xfed10000 0xfed15fff 0xfed10000 0xfed13fff pnp 00:01
>   Info: mapping multiple BARs. Your kernel is fine.
> 
> To prevent this, if we find a PNP0C02 resource that covers part of the MCH
> space, extend it to cover the entire space.
> 
> Link: http://lkml.kernel.org/r/20140224162400.GE16457@pd.tnic
> Reported-by: Borislav Petkov <bp@...en8.de>
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> ---
>  drivers/pnp/quirks.c |   55 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 55 insertions(+)
> 
> diff --git a/drivers/pnp/quirks.c b/drivers/pnp/quirks.c
> index 258fef272ea7..8402088d4145 100644
> --- a/drivers/pnp/quirks.c
> +++ b/drivers/pnp/quirks.c
> @@ -334,6 +334,60 @@ static void quirk_amd_mmconfig_area(struct pnp_dev *dev)
>  }
>  #endif
>  
> +static void quirk_intel_haswell_mch(struct pnp_dev *dev)
> +{
> +	struct pci_dev *host;
> +	u32 addr_lo, addr_hi;
> +	struct pci_bus_region region;
> +	struct resource mch;
> +	struct pnp_resource *pnp_res;
> +	struct resource *res;
> +
> +	host = pci_get_device(PCI_VENDOR_ID_INTEL, 0x0c00, NULL);

And because it is not HSW only, this PCI device ID doesn't match on my
IVB system. On mine the hostbridge is

00:00.0 Host bridge: Intel Corporation 3rd Gen Core processor DRAM Controller (rev 09)
        Subsystem: Lenovo Device 21fa
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ >SERR- <PERR- INTx-
        Latency: 0
        Capabilities: <access denied>
        Kernel driver in use: ivb_uncore
00: 86 80 54 01 06 00 90 20 09 00 00 06 00 00 00 00
10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 aa 17 fa 21
30: 00 00 00 00 e0 00 00 00 00 00 00 00 00 00 00 00

and from looking at Dave's, it is the same one, so PCI device ID is
0x154.

With that changed to

	host = pci_get_device(PCI_VENDOR_ID_INTEL, 0x0154, NULL);

and a bit of debugging code, it says now:

[    0.235739] quirk_intel_haswell_mch: entry
[    0.235800] quirk_intel_haswell_mch: got host: 0x0
[    0.235860] quirk_intel_haswell_mch: mch: [mem 0xfed10000-0xfed17fff]
[    0.235930] quirk_intel_haswell_mch: res: [mem 0xfed10000-0xfed13fff]
[    0.235990] pnp 00:01: [Firmware Bug]: [mem 0xfed10000-0xfed13fff] covers only part of Intel Haswell MCH; extending to [mem 0xfed10000-0xfed17fff]

So you probably want to have a list of hostbridge pci ids in the quirk
or so.

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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