Re: [PATCH 2] PNP: Work around BIOS defects in Intel MCH area reporting

[Stephane Eranian]

On Tue, Apr 22, 2014 at 12:17 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> Work around BIOSes that don't report the entire Intel MCH area.
>
> MCHBAR is not an architected PCI BAR, so MCH space is usually reported as a
> PNP0C02 resource.  The MCH space was once 16KB, but is 32KB in newer parts.
> Some 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.
>
Works for me on my Levono IvyBridge laptop.
Thanks for fixing this, Bjorn.
Acked-by: Stephane Eranian <eranian@xxxxxxxxxx>

> Link: http://lkml.kernel.org/r/20140224162400.GE16457@xxxxxxx
> Reported-by: Borislav Petkov <bp@xxxxxxxxx>
> Tested-by: Borislav Petkov <bp@xxxxxxx>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Acked-by: Borislav Petkov <bp@xxxxxxx>
> ---
>  drivers/pnp/quirks.c |   75 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 75 insertions(+)
>
> diff --git a/drivers/pnp/quirks.c b/drivers/pnp/quirks.c
> index 258fef272ea7..0d679068ef1b 100644
> --- a/drivers/pnp/quirks.c
> +++ b/drivers/pnp/quirks.c
> @@ -15,6 +15,7 @@
>
>  #include <linux/types.h>
>  #include <linux/kernel.h>
> +#include <linux/pci.h>
>  #include <linux/string.h>
>  #include <linux/slab.h>
>  #include <linux/pnp.h>
> @@ -334,6 +335,79 @@ static void quirk_amd_mmconfig_area(struct pnp_dev *dev)
>  }
>  #endif
>
> +/* Device IDs of parts that have 32KB MCH space */
> +static const unsigned int mch_quirk_devices[] = {
> +       0x0154, /* Ivy Bridge */
> +       0x0c00, /* Haswell */
> +};
> +
> +static struct pci_dev *get_intel_host(void)
> +{
> +       int i;
> +       struct pci_dev *host;
> +
> +       for (i = 0; i < ARRAY_SIZE(mch_quirk_devices); i++) {
> +               host = pci_get_device(PCI_VENDOR_ID_INTEL, mch_quirk_devices[i],
> +                                     NULL);
> +               if (host)
> +                       return host;
> +       }
> +       return NULL;
> +}
> +
> +static void quirk_intel_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 = get_intel_host();
> +       if (!host)
> +               return;
> +
> +       /*
> +        * MCHBAR is not an architected PCI BAR, so MCH space is usually
> +        * reported as a PNP0C02 resource.  The MCH space was originally
> +        * 16KB, but is 32KB in newer parts.  Some 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 |= (u64) addr_hi << 32;
> +       region.end = region.start + 32*1024 - 1;
> +
> +       memset(&mch, 0, sizeof(mch));
> +       mch.flags = IORESOURCE_MEM;
> +       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 "PNP resource %pR covers only part of %s Intel MCH; extending to %pR\n",
> +                        res, pci_name(host), &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 +438,7 @@ static struct pnp_fixup pnp_fixups[] = {
>  #ifdef CONFIG_AMD_NB
>         {"PNP0c01", quirk_amd_mmconfig_area},
>  #endif
> +       {"PNP0c02", quirk_intel_mch},
>         {""}
>  };
>
>
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