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

Stephane Eranian
2014-04-16T23:08:29Z

On Wed, Apr 16, 2014 at 1:31 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
> On Wed, Apr 16, 2014 at 09:04:04PM +0200, Borislav Petkov wrote:
>> On Thu, Mar 20, 2014 at 02:48:30PM -0600, Bjorn Helgaas wrote:
>> > Right. Even if we had this long-term solution, we'd still have
>> > Stephane's current problem, because the PNP0C02 _CRS is still wrong.
>> >
>> > We do have a drivers/pnp/quirks.c where we could conceivably adjust
>> > the PNP resource if we found the matching PCI device and MCHBAR. That
>> > should solve Stephane's problem even with the current
>> > drivers/pnp/system.c.
>>
>> Guys, this still triggers in -rc1. Do we have a fix or something
>> testable at least?
>
> Hi Boris,
>
> Can you try the patch below?
>
>
>
> PNP: Work around Haswell BIOS defect in MCH area reporting
>
> From: Bjorn Helgaas <bhelgaas@google.com>
>
> Work around a Haswell BIOS defect that causes part of the MCH area to be
> unreported.
>
> 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.
>
Why are you saying this is Haswell vs. others. I see the problem on my
IvyBridge laptop, like Boris.

> 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@alien8.de>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
> drivers/pnp/quirks.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 52 insertions(+)
>
> diff --git a/drivers/pnp/quirks.c b/drivers/pnp/quirks.c
> index 258fef272ea7..023edf592371 100644
> --- a/drivers/pnp/quirks.c
> +++ b/drivers/pnp/quirks.c
> @@ -334,6 +334,57 @@ 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);
> + if (!host)
> + return;
> +
> + /*
> + * 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.
> + */
> +
> + /*
> + * Read MCHBAR for Host Member Mapped Register Range Base
> + * https://www-ssl.intel.com/content/www/us/en/processors/core/4th-gen-core-family-desktop-vol-2-datasheet
> + * Sec 3.1.12.
> + */
> + pci_read_config_dword(host, 0x48, &addr_lo);
> + region.start = addr_lo & ~0x7fff;
> + pci_read_config_dword(host, 0x4c, &addr_hi);
> + region.start |= (dma_addr_t) addr_hi << 32;
> + region.end = region.start + 32*1024 - 1 ;
> + pcibios_bus_to_resource(host->bus, &mch, &region);
> +
> + list_for_each_entry(pnp_res, &dev->resources, list) {
> + res = &pnp_res->res;
> + if (res->end < mch.start || res->start > mch.end)
> + continue; /* no overlap */
> + if (res->start == mch.start && res->end == mch.end)
> + continue; /* exact match */
> +
> + dev_info(&dev->dev, FW_BUG
> + "%pR covers only part of Intel Haswell MCH; extending to %pR\n",
> + res, &mch);
> + res->start = mch.start;
> + res->end = mch.end;
> + break;
> + }
> +
> + pci_dev_put(host);
> +}
> +
> /*
> * PnP Quirks
> * Cards or devices that need some tweaking due to incomplete resource info
> @@ -364,6 +415,7 @@ static struct pnp_fixup pnp_fixups[] = {
> #ifdef CONFIG_AMD_NB
> {"PNP0c01", quirk_amd_mmconfig_area},
> #endif
> + {"PNP0c02", quirk_intel_haswell_mch},
> {""}
> };
>