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

Stephane Eranian
2014-04-23T13:54:47Z

On Tue, Apr 22, 2014 at 12:17 AM, Bjorn Helgaas <bhelgaas@google.com> 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@google.com>

> Link: http://lkml.kernel.org/r/20140224162400.GE16457@pd.tnic
> Reported-by: Borislav Petkov <bp@alien8.de>
> Tested-by: Borislav Petkov <bp@suse.de>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> Acked-by: Borislav Petkov <bp@suse.de>
> ---
> 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},
> {""}
> };
>
>