Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 524 insertions, 0 deletions

diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
new file mode 100644
index 000000000..8ea24df3c
--- /dev/null
+++ b/arch/x86/kernel/amd_nb.c
@@ -0,0 +1,524 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Shared support code for AMD K8 northbridges and derivatives.
+ * Copyright 2006 Andi Kleen, SUSE Labs.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/pci_ids.h>
+#include <asm/amd_nb.h>
+
+#define PCI_DEVICE_ID_AMD_17H_ROOT	0x1450
+#define PCI_DEVICE_ID_AMD_17H_M10H_ROOT	0x15d0
+#define PCI_DEVICE_ID_AMD_17H_M30H_ROOT	0x1480
+#define PCI_DEVICE_ID_AMD_17H_M60H_ROOT	0x1630
+#define PCI_DEVICE_ID_AMD_17H_MA0H_ROOT	0x14b5
+#define PCI_DEVICE_ID_AMD_19H_M10H_ROOT	0x14a4
+#define PCI_DEVICE_ID_AMD_19H_M60H_ROOT	0x14d8
+#define PCI_DEVICE_ID_AMD_19H_M70H_ROOT	0x14e8
+#define PCI_DEVICE_ID_AMD_17H_DF_F4	0x1464
+#define PCI_DEVICE_ID_AMD_17H_M10H_DF_F4 0x15ec
+#define PCI_DEVICE_ID_AMD_17H_M30H_DF_F4 0x1494
+#define PCI_DEVICE_ID_AMD_17H_M60H_DF_F4 0x144c
+#define PCI_DEVICE_ID_AMD_17H_M70H_DF_F4 0x1444
+#define PCI_DEVICE_ID_AMD_17H_MA0H_DF_F4 0x1728
+#define PCI_DEVICE_ID_AMD_19H_DF_F4	0x1654
+#define PCI_DEVICE_ID_AMD_19H_M10H_DF_F4 0x14b1
+#define PCI_DEVICE_ID_AMD_19H_M40H_ROOT	0x14b5
+#define PCI_DEVICE_ID_AMD_19H_M40H_DF_F4 0x167d
+#define PCI_DEVICE_ID_AMD_19H_M50H_DF_F4 0x166e
+#define PCI_DEVICE_ID_AMD_19H_M60H_DF_F4 0x14e4
+#define PCI_DEVICE_ID_AMD_19H_M70H_DF_F4 0x14f4
+#define PCI_DEVICE_ID_AMD_19H_M78H_DF_F4 0x12fc
+
+/* Protect the PCI config register pairs used for SMN. */
+static DEFINE_MUTEX(smn_mutex);
+
+static u32 *flush_words;
+
+static const struct pci_device_id amd_root_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_ROOT) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M10H_ROOT) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M30H_ROOT) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M60H_ROOT) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_MA0H_ROOT) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M10H_ROOT) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_ROOT) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M60H_ROOT) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M70H_ROOT) },
+	{}
+};
+
+#define PCI_DEVICE_ID_AMD_CNB17H_F4     0x1704
+
+static const struct pci_device_id amd_nb_misc_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB_MISC) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_10H_NB_MISC) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_NB_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M10H_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M60H_NB_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_NB_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_M30H_NB_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M10H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M30H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M60H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_MA0H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CNB17H_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M70H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M10H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M50H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M60H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M70H_DF_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M78H_DF_F3) },
+	{}
+};
+
+static const struct pci_device_id amd_nb_link_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_NB_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M60H_NB_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_NB_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_M30H_NB_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M10H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M30H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M60H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_M70H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_17H_MA0H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M10H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M40H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M50H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M60H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M70H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_19H_M78H_DF_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CNB17H_F4) },
+	{}
+};
+
+static const struct pci_device_id hygon_root_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_17H_ROOT) },
+	{}
+};
+
+static const struct pci_device_id hygon_nb_misc_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_17H_DF_F3) },
+	{}
+};
+
+static const struct pci_device_id hygon_nb_link_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_HYGON, PCI_DEVICE_ID_AMD_17H_DF_F4) },
+	{}
+};
+
+const struct amd_nb_bus_dev_range amd_nb_bus_dev_ranges[] __initconst = {
+	{ 0x00, 0x18, 0x20 },
+	{ 0xff, 0x00, 0x20 },
+	{ 0xfe, 0x00, 0x20 },
+	{ }
+};
+
+static struct amd_northbridge_info amd_northbridges;
+
+u16 amd_nb_num(void)
+{
+	return amd_northbridges.num;
+}
+EXPORT_SYMBOL_GPL(amd_nb_num);
+
+bool amd_nb_has_feature(unsigned int feature)
+{
+	return ((amd_northbridges.flags & feature) == feature);
+}
+EXPORT_SYMBOL_GPL(amd_nb_has_feature);
+
+struct amd_northbridge *node_to_amd_nb(int node)
+{
+	return (node < amd_northbridges.num) ? &amd_northbridges.nb[node] : NULL;
+}
+EXPORT_SYMBOL_GPL(node_to_amd_nb);
+
+static struct pci_dev *next_northbridge(struct pci_dev *dev,
+					const struct pci_device_id *ids)
+{
+	do {
+		dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
+		if (!dev)
+			break;
+	} while (!pci_match_id(ids, dev));
+	return dev;
+}
+
+static int __amd_smn_rw(u16 node, u32 address, u32 *value, bool write)
+{
+	struct pci_dev *root;
+	int err = -ENODEV;
+
+	if (node >= amd_northbridges.num)
+		goto out;
+
+	root = node_to_amd_nb(node)->root;
+	if (!root)
+		goto out;
+
+	mutex_lock(&smn_mutex);
+
+	err = pci_write_config_dword(root, 0x60, address);
+	if (err) {
+		pr_warn("Error programming SMN address 0x%x.\n", address);
+		goto out_unlock;
+	}
+
+	err = (write ? pci_write_config_dword(root, 0x64, *value)
+		     : pci_read_config_dword(root, 0x64, value));
+	if (err)
+		pr_warn("Error %s SMN address 0x%x.\n",
+			(write ? "writing to" : "reading from"), address);
+
+out_unlock:
+	mutex_unlock(&smn_mutex);
+
+out:
+	return err;
+}
+
+int amd_smn_read(u16 node, u32 address, u32 *value)
+{
+	return __amd_smn_rw(node, address, value, false);
+}
+EXPORT_SYMBOL_GPL(amd_smn_read);
+
+int amd_smn_write(u16 node, u32 address, u32 value)
+{
+	return __amd_smn_rw(node, address, &value, true);
+}
+EXPORT_SYMBOL_GPL(amd_smn_write);
+
+
+static int amd_cache_northbridges(void)
+{
+	const struct pci_device_id *misc_ids = amd_nb_misc_ids;
+	const struct pci_device_id *link_ids = amd_nb_link_ids;
+	const struct pci_device_id *root_ids = amd_root_ids;
+	struct pci_dev *root, *misc, *link;
+	struct amd_northbridge *nb;
+	u16 roots_per_misc = 0;
+	u16 misc_count = 0;
+	u16 root_count = 0;
+	u16 i, j;
+
+	if (amd_northbridges.num)
+		return 0;
+
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
+		root_ids = hygon_root_ids;
+		misc_ids = hygon_nb_misc_ids;
+		link_ids = hygon_nb_link_ids;
+	}
+
+	misc = NULL;
+	while ((misc = next_northbridge(misc, misc_ids)))
+		misc_count++;
+
+	if (!misc_count)
+		return -ENODEV;
+
+	root = NULL;
+	while ((root = next_northbridge(root, root_ids)))
+		root_count++;
+
+	if (root_count) {
+		roots_per_misc = root_count / misc_count;
+
+		/*
+		 * There should be _exactly_ N roots for each DF/SMN
+		 * interface.
+		 */
+		if (!roots_per_misc || (root_count % roots_per_misc)) {
+			pr_info("Unsupported AMD DF/PCI configuration found\n");
+			return -ENODEV;
+		}
+	}
+
+	nb = kcalloc(misc_count, sizeof(struct amd_northbridge), GFP_KERNEL);
+	if (!nb)
+		return -ENOMEM;
+
+	amd_northbridges.nb = nb;
+	amd_northbridges.num = misc_count;
+
+	link = misc = root = NULL;
+	for (i = 0; i < amd_northbridges.num; i++) {
+		node_to_amd_nb(i)->root = root =
+			next_northbridge(root, root_ids);
+		node_to_amd_nb(i)->misc = misc =
+			next_northbridge(misc, misc_ids);
+		node_to_amd_nb(i)->link = link =
+			next_northbridge(link, link_ids);
+
+		/*
+		 * If there are more PCI root devices than data fabric/
+		 * system management network interfaces, then the (N)
+		 * PCI roots per DF/SMN interface are functionally the
+		 * same (for DF/SMN access) and N-1 are redundant.  N-1
+		 * PCI roots should be skipped per DF/SMN interface so
+		 * the following DF/SMN interfaces get mapped to
+		 * correct PCI roots.
+		 */
+		for (j = 1; j < roots_per_misc; j++)
+			root = next_northbridge(root, root_ids);
+	}
+
+	if (amd_gart_present())
+		amd_northbridges.flags |= AMD_NB_GART;
+
+	/*
+	 * Check for L3 cache presence.
+	 */
+	if (!cpuid_edx(0x80000006))
+		return 0;
+
+	/*
+	 * Some CPU families support L3 Cache Index Disable. There are some
+	 * limitations because of E382 and E388 on family 0x10.
+	 */
+	if (boot_cpu_data.x86 == 0x10 &&
+	    boot_cpu_data.x86_model >= 0x8 &&
+	    (boot_cpu_data.x86_model > 0x9 ||
+	     boot_cpu_data.x86_stepping >= 0x1))
+		amd_northbridges.flags |= AMD_NB_L3_INDEX_DISABLE;
+
+	if (boot_cpu_data.x86 == 0x15)
+		amd_northbridges.flags |= AMD_NB_L3_INDEX_DISABLE;
+
+	/* L3 cache partitioning is supported on family 0x15 */
+	if (boot_cpu_data.x86 == 0x15)
+		amd_northbridges.flags |= AMD_NB_L3_PARTITIONING;
+
+	return 0;
+}
+
+/*
+ * Ignores subdevice/subvendor but as far as I can figure out
+ * they're useless anyways
+ */
+bool __init early_is_amd_nb(u32 device)
+{
+	const struct pci_device_id *misc_ids = amd_nb_misc_ids;
+	const struct pci_device_id *id;
+	u32 vendor = device & 0xffff;
+
+	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
+	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
+		return false;
+
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
+		misc_ids = hygon_nb_misc_ids;
+
+	device >>= 16;
+	for (id = misc_ids; id->vendor; id++)
+		if (vendor == id->vendor && device == id->device)
+			return true;
+	return false;
+}
+
+struct resource *amd_get_mmconfig_range(struct resource *res)
+{
+	u32 address;
+	u64 base, msr;
+	unsigned int segn_busn_bits;
+
+	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
+	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
+		return NULL;
+
+	/* assume all cpus from fam10h have mmconfig */
+	if (boot_cpu_data.x86 < 0x10)
+		return NULL;
+
+	address = MSR_FAM10H_MMIO_CONF_BASE;
+	rdmsrl(address, msr);
+
+	/* mmconfig is not enabled */
+	if (!(msr & FAM10H_MMIO_CONF_ENABLE))
+		return NULL;
+
+	base = msr & (FAM10H_MMIO_CONF_BASE_MASK<<FAM10H_MMIO_CONF_BASE_SHIFT);
+
+	segn_busn_bits = (msr >> FAM10H_MMIO_CONF_BUSRANGE_SHIFT) &
+			 FAM10H_MMIO_CONF_BUSRANGE_MASK;
+
+	res->flags = IORESOURCE_MEM;
+	res->start = base;
+	res->end = base + (1ULL<<(segn_busn_bits + 20)) - 1;
+	return res;
+}
+
+int amd_get_subcaches(int cpu)
+{
+	struct pci_dev *link = node_to_amd_nb(topology_die_id(cpu))->link;
+	unsigned int mask;
+
+	if (!amd_nb_has_feature(AMD_NB_L3_PARTITIONING))
+		return 0;
+
+	pci_read_config_dword(link, 0x1d4, &mask);
+
+	return (mask >> (4 * cpu_data(cpu).cpu_core_id)) & 0xf;
+}
+
+int amd_set_subcaches(int cpu, unsigned long mask)
+{
+	static unsigned int reset, ban;
+	struct amd_northbridge *nb = node_to_amd_nb(topology_die_id(cpu));
+	unsigned int reg;
+	int cuid;
+
+	if (!amd_nb_has_feature(AMD_NB_L3_PARTITIONING) || mask > 0xf)
+		return -EINVAL;
+
+	/* if necessary, collect reset state of L3 partitioning and BAN mode */
+	if (reset == 0) {
+		pci_read_config_dword(nb->link, 0x1d4, &reset);
+		pci_read_config_dword(nb->misc, 0x1b8, &ban);
+		ban &= 0x180000;
+	}
+
+	/* deactivate BAN mode if any subcaches are to be disabled */
+	if (mask != 0xf) {
+		pci_read_config_dword(nb->misc, 0x1b8, &reg);
+		pci_write_config_dword(nb->misc, 0x1b8, reg & ~0x180000);
+	}
+
+	cuid = cpu_data(cpu).cpu_core_id;
+	mask <<= 4 * cuid;
+	mask |= (0xf ^ (1 << cuid)) << 26;
+
+	pci_write_config_dword(nb->link, 0x1d4, mask);
+
+	/* reset BAN mode if L3 partitioning returned to reset state */
+	pci_read_config_dword(nb->link, 0x1d4, &reg);
+	if (reg == reset) {
+		pci_read_config_dword(nb->misc, 0x1b8, &reg);
+		reg &= ~0x180000;
+		pci_write_config_dword(nb->misc, 0x1b8, reg | ban);
+	}
+
+	return 0;
+}
+
+static void amd_cache_gart(void)
+{
+	u16 i;
+
+	if (!amd_nb_has_feature(AMD_NB_GART))
+		return;
+
+	flush_words = kmalloc_array(amd_northbridges.num, sizeof(u32), GFP_KERNEL);
+	if (!flush_words) {
+		amd_northbridges.flags &= ~AMD_NB_GART;
+		pr_notice("Cannot initialize GART flush words, GART support disabled\n");
+		return;
+	}
+
+	for (i = 0; i != amd_northbridges.num; i++)
+		pci_read_config_dword(node_to_amd_nb(i)->misc, 0x9c, &flush_words[i]);
+}
+
+void amd_flush_garts(void)
+{
+	int flushed, i;
+	unsigned long flags;
+	static DEFINE_SPINLOCK(gart_lock);
+
+	if (!amd_nb_has_feature(AMD_NB_GART))
+		return;
+
+	/*
+	 * Avoid races between AGP and IOMMU. In theory it's not needed
+	 * but I'm not sure if the hardware won't lose flush requests
+	 * when another is pending. This whole thing is so expensive anyways
+	 * that it doesn't matter to serialize more. -AK
+	 */
+	spin_lock_irqsave(&gart_lock, flags);
+	flushed = 0;
+	for (i = 0; i < amd_northbridges.num; i++) {
+		pci_write_config_dword(node_to_amd_nb(i)->misc, 0x9c,
+				       flush_words[i] | 1);
+		flushed++;
+	}
+	for (i = 0; i < amd_northbridges.num; i++) {
+		u32 w;
+		/* Make sure the hardware actually executed the flush*/
+		for (;;) {
+			pci_read_config_dword(node_to_amd_nb(i)->misc,
+					      0x9c, &w);
+			if (!(w & 1))
+				break;
+			cpu_relax();
+		}
+	}
+	spin_unlock_irqrestore(&gart_lock, flags);
+	if (!flushed)
+		pr_notice("nothing to flush?\n");
+}
+EXPORT_SYMBOL_GPL(amd_flush_garts);
+
+static void __fix_erratum_688(void *info)
+{
+#define MSR_AMD64_IC_CFG 0xC0011021
+
+	msr_set_bit(MSR_AMD64_IC_CFG, 3);
+	msr_set_bit(MSR_AMD64_IC_CFG, 14);
+}
+
+/* Apply erratum 688 fix so machines without a BIOS fix work. */
+static __init void fix_erratum_688(void)
+{
+	struct pci_dev *F4;
+	u32 val;
+
+	if (boot_cpu_data.x86 != 0x14)
+		return;
+
+	if (!amd_northbridges.num)
+		return;
+
+	F4 = node_to_amd_nb(0)->link;
+	if (!F4)
+		return;
+
+	if (pci_read_config_dword(F4, 0x164, &val))
+		return;
+
+	if (val & BIT(2))
+		return;
+
+	on_each_cpu(__fix_erratum_688, NULL, 0);
+
+	pr_info("x86/cpu/AMD: CPU erratum 688 worked around\n");
+}
+
+static __init int init_amd_nbs(void)
+{
+	amd_cache_northbridges();
+	amd_cache_gart();
+
+	fix_erratum_688();
+
+	return 0;
+}
+
+/* This has to go after the PCI subsystem */
+fs_initcall(init_amd_nbs);