linux-kernel - [PATCH 2] PNP: Work around BIOS defects in Intel MCH area reporting

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Message-ID: <20140421221721.26308.1891.stgit@bhelgaas-glaptop.roam.corp.google.com>
Date:	Mon, 21 Apr 2014 16:17:21 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Aaron Lu <aaron.lu@...el.com>, linux-pci@...r.kernel.org,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	Stephane Eranian <eranian@...gle.com>,
	linux-acpi@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Zheng Z Yan <zheng.z.yan@...el.com>,
	Dave Jones <davej@...hat.com>, Rui Zhang <rui.zhang@...el.com>,
	Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH 2] PNP: Work around BIOS defects in Intel MCH area reporting

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.

Link: http://lkml.kernel.org/r/20140224162400.GE16457@pd.tnic
Reported-by: Borislav Petkov <bp@...en8.de>
Tested-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Acked-by: Borislav Petkov <bp@...e.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},
 	{""}
 };
 

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