arch/x86/kernel/cpu/mce/inject.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Machine check injection support.
 * Copyright 2008 Intel Corporation.
 *
 * Authors:
 * Andi Kleen
 * Ying Huang
 *
 * The AMD part (from mce_amd_inj.c): a simple MCE injection facility
 * for testing different aspects of the RAS code. This driver should be
 * built as module so that it can be loaded on production kernels for
 * testing purposes.
 *
 * Copyright (c) 2010-17:  Borislav Petkov <bp@alien8.de>
 *			   Advanced Micro Devices Inc.
 */

#include <linux/cpu.h>
#include <linux/debugfs.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/pci.h>
#include <linux/uaccess.h>

#include <asm/amd_nb.h>
#include <asm/apic.h>
#include <asm/irq_vectors.h>
#include <asm/mce.h>
#include <asm/nmi.h>
#include <asm/smp.h>

#include "internal.h"

/*
 * Collect all the MCi_XXX settings
 */
static struct mce i_mce;
static struct dentry *dfs_inj;

#define MAX_FLAG_OPT_SIZE	4
#define NBCFG			0x44

enum injection_type {
	SW_INJ = 0,	/* SW injection, simply decode the error */
	HW_INJ,		/* Trigger a #MC */
	DFR_INT_INJ,    /* Trigger Deferred error interrupt */
	THR_INT_INJ,    /* Trigger threshold interrupt */
	N_INJ_TYPES,
};

static const char * const flags_options[] = {
	[SW_INJ] = "sw",
	[HW_INJ] = "hw",
	[DFR_INT_INJ] = "df",
	[THR_INT_INJ] = "th",
	NULL
};

/* Set default injection to SW_INJ */
static enum injection_type inj_type = SW_INJ;

#define MCE_INJECT_SET(reg)						\
static int inj_##reg##_set(void *data, u64 val)				\
{									\
	struct mce *m = (struct mce *)data;				\
									\
	m->reg = val;							\
	return 0;							\
}

MCE_INJECT_SET(status);
MCE_INJECT_SET(misc);
MCE_INJECT_SET(addr);
MCE_INJECT_SET(synd);

#define MCE_INJECT_GET(reg)						\
static int inj_##reg##_get(void *data, u64 *val)			\
{									\
	struct mce *m = (struct mce *)data;				\
									\
	*val = m->reg;							\
	return 0;							\
}

MCE_INJECT_GET(status);
MCE_INJECT_GET(misc);
MCE_INJECT_GET(addr);
MCE_INJECT_GET(synd);

DEFINE_SIMPLE_ATTRIBUTE(status_fops, inj_status_get, inj_status_set, "%llx\n");
DEFINE_SIMPLE_ATTRIBUTE(misc_fops, inj_misc_get, inj_misc_set, "%llx\n");
DEFINE_SIMPLE_ATTRIBUTE(addr_fops, inj_addr_get, inj_addr_set, "%llx\n");
DEFINE_SIMPLE_ATTRIBUTE(synd_fops, inj_synd_get, inj_synd_set, "%llx\n");

static void setup_inj_struct(struct mce *m)
{
	memset(m, 0, sizeof(struct mce));

	m->cpuvendor = boot_cpu_data.x86_vendor;
	m->time	     = ktime_get_real_seconds();
	m->cpuid     = cpuid_eax(1);
	m->microcode = boot_cpu_data.microcode;
}

/* Update fake mce registers on current CPU. */
static void inject_mce(struct mce *m)
{
	struct mce *i = &per_cpu(injectm, m->extcpu);

	/* Make sure no one reads partially written injectm */
	i->finished = 0;
	mb();
	m->finished = 0;
	/* First set the fields after finished */
	i->extcpu = m->extcpu;
	mb();
	/* Now write record in order, finished last (except above) */
	memcpy(i, m, sizeof(struct mce));
	/* Finally activate it */
	mb();
	i->finished = 1;
}

static void raise_poll(struct mce *m)
{
	unsigned long flags;
	mce_banks_t b;

	memset(&b, 0xff, sizeof(mce_banks_t));
	local_irq_save(flags);
	machine_check_poll(0, &b);
	local_irq_restore(flags);
	m->finished = 0;
}

static void raise_exception(struct mce *m, struct pt_regs *pregs)
{
	struct pt_regs regs;
	unsigned long flags;

	if (!pregs) {
		memset(&regs, 0, sizeof(struct pt_regs));
		regs.ip = m->ip;
		regs.cs = m->cs;
		pregs = &regs;
	}
	/* in mcheck exeception handler, irq will be disabled */
	local_irq_save(flags);
	do_machine_check(pregs, 0);
	local_irq_restore(flags);
	m->finished = 0;
}

static cpumask_var_t mce_inject_cpumask;
static DEFINE_MUTEX(mce_inject_mutex);

static int mce_raise_notify(unsigned int cmd, struct pt_regs *regs)
{
	int cpu = smp_processor_id();
	struct mce *m = this_cpu_ptr(&injectm);
	if (!cpumask_test_cpu(cpu, mce_inject_cpumask))
		return NMI_DONE;
	cpumask_clear_cpu(cpu, mce_inject_cpumask);
	if (m->inject_flags & MCJ_EXCEPTION)
		raise_exception(m, regs);
	else if (m->status)
		raise_poll(m);
	return NMI_HANDLED;
}

static void mce_irq_ipi(void *info)
{
	int cpu = smp_processor_id();
	struct mce *m = this_cpu_ptr(&injectm);

	if (cpumask_test_cpu(cpu, mce_inject_cpumask) &&
			m->inject_flags & MCJ_EXCEPTION) {
		cpumask_clear_cpu(cpu, mce_inject_cpumask);
		raise_exception(m, NULL);
	}
}

/* Inject mce on current CPU */
static int raise_local(void)
{
	struct mce *m = this_cpu_ptr(&injectm);
	int context = MCJ_CTX(m->inject_flags);
	int ret = 0;
	int cpu = m->extcpu;

	if (m->inject_flags & MCJ_EXCEPTION) {
		pr_info("Triggering MCE exception on CPU %d\n", cpu);
		switch (context) {
		case MCJ_CTX_IRQ:
			/*
			 * Could do more to fake interrupts like
			 * calling irq_enter, but the necessary
			 * machinery isn't exported currently.
			 */
			/*FALL THROUGH*/
		case MCJ_CTX_PROCESS:
			raise_exception(m, NULL);
			break;
		default:
			pr_info("Invalid MCE context\n");
			ret = -EINVAL;
		}
		pr_info("MCE exception done on CPU %d\n", cpu);
	} else if (m->status) {
		pr_info("Starting machine check poll CPU %d\n", cpu);
		raise_poll(m);
		mce_notify_irq();
		pr_info("Machine check poll done on CPU %d\n", cpu);
	} else
		m->finished = 0;

	return ret;
}

static void __maybe_unused raise_mce(struct mce *m)
{
	int context = MCJ_CTX(m->inject_flags);

	inject_mce(m);

	if (context == MCJ_CTX_RANDOM)
		return;

	if (m->inject_flags & (MCJ_IRQ_BROADCAST | MCJ_NMI_BROADCAST)) {
		unsigned long start;
		int cpu;

		get_online_cpus();
		cpumask_copy(mce_inject_cpumask, cpu_online_mask);
		cpumask_clear_cpu(get_cpu(), mce_inject_cpumask);
		for_each_online_cpu(cpu) {
			struct mce *mcpu = &per_cpu(injectm, cpu);
			if (!mcpu->finished ||
			    MCJ_CTX(mcpu->inject_flags) != MCJ_CTX_RANDOM)
				cpumask_clear_cpu(cpu, mce_inject_cpumask);
		}
		if (!cpumask_empty(mce_inject_cpumask)) {
			if (m->inject_flags & MCJ_IRQ_BROADCAST) {
				/*
				 * don't wait because mce_irq_ipi is necessary
				 * to be sync with following raise_local
				 */
				preempt_disable();
				smp_call_function_many(mce_inject_cpumask,
					mce_irq_ipi, NULL, 0);
				preempt_enable();
			} else if (m->inject_flags & MCJ_NMI_BROADCAST)
				apic->send_IPI_mask(mce_inject_cpumask,
						NMI_VECTOR);
		}
		start = jiffies;
		while (!cpumask_empty(mce_inject_cpumask)) {
			if (!time_before(jiffies, start + 2*HZ)) {
				pr_err("Timeout waiting for mce inject %lx\n",
					*cpumask_bits(mce_inject_cpumask));
				break;
			}
			cpu_relax();
		}
		raise_local();
		put_cpu();
		put_online_cpus();
	} else {
		preempt_disable();
		raise_local();
		preempt_enable();
	}
}

static int mce_inject_raise(struct notifier_block *nb, unsigned long val,
			    void *data)
{
	struct mce *m = (struct mce *)data;

	if (!m)
		return NOTIFY_DONE;

	mutex_lock(&mce_inject_mutex);
	raise_mce(m);
	mutex_unlock(&mce_inject_mutex);

	return NOTIFY_DONE;
}

static struct notifier_block inject_nb = {
	.notifier_call  = mce_inject_raise,
};

/*
 * Caller needs to be make sure this cpu doesn't disappear
 * from under us, i.e.: get_cpu/put_cpu.
 */
static int toggle_hw_mce_inject(unsigned int cpu, bool enable)
{
	u32 l, h;
	int err;

	err = rdmsr_on_cpu(cpu, MSR_K7_HWCR, &l, &h);
	if (err) {
		pr_err("%s: error reading HWCR\n", __func__);
		return err;
	}

	enable ? (l |= BIT(18)) : (l &= ~BIT(18));

	err = wrmsr_on_cpu(cpu, MSR_K7_HWCR, l, h);
	if (err)
		pr_err("%s: error writing HWCR\n", __func__);

	return err;
}

static int __set_inj(const char *buf)
{
	int i;

	for (i = 0; i < N_INJ_TYPES; i++) {
		if (!strncmp(flags_options[i], buf, strlen(flags_options[i]))) {
			inj_type = i;
			return 0;
		}
	}
	return -EINVAL;
}

static ssize_t flags_read(struct file *filp, char __user *ubuf,
			  size_t cnt, loff_t *ppos)
{
	char buf[MAX_FLAG_OPT_SIZE];
	int n;

	n = sprintf(buf, "%s\n", flags_options[inj_type]);

	return simple_read_from_buffer(ubuf, cnt, ppos, buf, n);
}

static ssize_t flags_write(struct file *filp, const char __user *ubuf,
			   size_t cnt, loff_t *ppos)
{
	char buf[MAX_FLAG_OPT_SIZE], *__buf;
	int err;

	if (cnt > MAX_FLAG_OPT_SIZE)
		return -EINVAL;

	if (copy_from_user(&buf, ubuf, cnt))
		return -EFAULT;

	buf[cnt - 1] = 0;

	/* strip whitespace */
	__buf = strstrip(buf);

	err = __set_inj(__buf);
	if (err) {
		pr_err("%s: Invalid flags value: %s\n", __func__, __buf);
		return err;
	}

	*ppos += cnt;

	return cnt;
}

static const struct file_operations flags_fops = {
	.read           = flags_read,
	.write          = flags_write,
	.llseek         = generic_file_llseek,
};

/*
 * On which CPU to inject?
 */
MCE_INJECT_GET(extcpu);

static int inj_extcpu_set(void *data, u64 val)
{
	struct mce *m = (struct mce *)data;

	if (val >= nr_cpu_ids || !cpu_online(val)) {
		pr_err("%s: Invalid CPU: %llu\n", __func__, val);
		return -EINVAL;
	}
	m->extcpu = val;
	return 0;
}

DEFINE_SIMPLE_ATTRIBUTE(extcpu_fops, inj_extcpu_get, inj_extcpu_set, "%llu\n");

static void trigger_mce(void *info)
{
	asm volatile("int $18");
}

static void trigger_dfr_int(void *info)
{
	asm volatile("int %0" :: "i" (DEFERRED_ERROR_VECTOR));
}

static void trigger_thr_int(void *info)
{
	asm volatile("int %0" :: "i" (THRESHOLD_APIC_VECTOR));
}

static u32 get_nbc_for_node(int node_id)
{
	struct cpuinfo_x86 *c = &boot_cpu_data;
	u32 cores_per_node;

	cores_per_node = (c->x86_max_cores * smp_num_siblings) / amd_get_nodes_per_socket();

	return cores_per_node * node_id;
}

static void toggle_nb_mca_mst_cpu(u16 nid)
{
	struct amd_northbridge *nb;
	struct pci_dev *F3;
	u32 val;
	int err;

	nb = node_to_amd_nb(nid);
	if (!nb)
		return;

	F3 = nb->misc;
	if (!F3)
		return;

	err = pci_read_config_dword(F3, NBCFG, &val);
	if (err) {
		pr_err("%s: Error reading F%dx%03x.\n",
		       __func__, PCI_FUNC(F3->devfn), NBCFG);
		return;
	}

	if (val & BIT(27))
		return;

	pr_err("%s: Set D18F3x44[NbMcaToMstCpuEn] which BIOS hasn't done.\n",
	       __func__);

	val |= BIT(27);
	err = pci_write_config_dword(F3, NBCFG, val);
	if (err)
		pr_err("%s: Error writing F%dx%03x.\n",
		       __func__, PCI_FUNC(F3->devfn), NBCFG);
}

static void prepare_msrs(void *info)
{
	struct mce m = *(struct mce *)info;
	u8 b = m.bank;

	wrmsrl(MSR_IA32_MCG_STATUS, m.mcgstatus);

	if (boot_cpu_has(X86_FEATURE_SMCA)) {
		if (m.inject_flags == DFR_INT_INJ) {
			wrmsrl(MSR_AMD64_SMCA_MCx_DESTAT(b), m.status);
			wrmsrl(MSR_AMD64_SMCA_MCx_DEADDR(b), m.addr);
		} else {
			wrmsrl(MSR_AMD64_SMCA_MCx_STATUS(b), m.status);
			wrmsrl(MSR_AMD64_SMCA_MCx_ADDR(b), m.addr);
		}

		wrmsrl(MSR_AMD64_SMCA_MCx_MISC(b), m.misc);
		wrmsrl(MSR_AMD64_SMCA_MCx_SYND(b), m.synd);
	} else {
		wrmsrl(MSR_IA32_MCx_STATUS(b), m.status);
		wrmsrl(MSR_IA32_MCx_ADDR(b), m.addr);
		wrmsrl(MSR_IA32_MCx_MISC(b), m.misc);
	}
}

static void do_inject(void)
{
	u64 mcg_status = 0;
	unsigned int cpu = i_mce.extcpu;
	u8 b = i_mce.bank;

	i_mce.tsc = rdtsc_ordered();

	if (i_mce.misc)
		i_mce.status |= MCI_STATUS_MISCV;

	if (i_mce.synd)
		i_mce.status |= MCI_STATUS_SYNDV;

	if (inj_type == SW_INJ) {
		mce_inject_log(&i_mce);
		return;
	}

	/* prep MCE global settings for the injection */
	mcg_status = MCG_STATUS_MCIP | MCG_STATUS_EIPV;

	if (!(i_mce.status & MCI_STATUS_PCC))
		mcg_status |= MCG_STATUS_RIPV;

	/*
	 * Ensure necessary status bits for deferred errors:
	 * - MCx_STATUS[Deferred]: make sure it is a deferred error
	 * - MCx_STATUS[UC] cleared: deferred errors are _not_ UC
	 */
	if (inj_type == DFR_INT_INJ) {
		i_mce.status |= MCI_STATUS_DEFERRED;
		i_mce.status |= (i_mce.status & ~MCI_STATUS_UC);
	}

	/*
	 * For multi node CPUs, logging and reporting of bank 4 errors happens
	 * only on the node base core. Refer to D18F3x44[NbMcaToMstCpuEn] for
	 * Fam10h and later BKDGs.
	 */
	if (boot_cpu_has(X86_FEATURE_AMD_DCM) &&
	    b == 4 &&
	    boot_cpu_data.x86 < 0x17) {
		toggle_nb_mca_mst_cpu(amd_get_nb_id(cpu));
		cpu = get_nbc_for_node(amd_get_nb_id(cpu));
	}

	get_online_cpus();
	if (!cpu_online(cpu))
		goto err;

	toggle_hw_mce_inject(cpu, true);

	i_mce.mcgstatus = mcg_status;
	i_mce.inject_flags = inj_type;
	smp_call_function_single(cpu, prepare_msrs, &i_mce, 0);

	toggle_hw_mce_inject(cpu, false);

	switch (inj_type) {
	case DFR_INT_INJ:
		smp_call_function_single(cpu, trigger_dfr_int, NULL, 0);
		break;
	case THR_INT_INJ:
		smp_call_function_single(cpu, trigger_thr_int, NULL, 0);
		break;
	default:
		smp_call_function_single(cpu, trigger_mce, NULL, 0);
	}

err:
	put_online_cpus();

}

/*
 * This denotes into which bank we're injecting and triggers
 * the injection, at the same time.
 */
static int inj_bank_set(void *data, u64 val)
{
	struct mce *m = (struct mce *)data;
	u8 n_banks;
	u64 cap;

	/* Get bank count on target CPU so we can handle non-uniform values. */
	rdmsrl_on_cpu(m->extcpu, MSR_IA32_MCG_CAP, &cap);
	n_banks = cap & MCG_BANKCNT_MASK;

	if (val >= n_banks) {
		pr_err("MCA bank %llu non-existent on CPU%d\n", val, m->extcpu);
		return -EINVAL;
	}

	m->bank = val;
	do_inject();

	/* Reset injection struct */
	setup_inj_struct(&i_mce);

	return 0;
}

MCE_INJECT_GET(bank);

DEFINE_SIMPLE_ATTRIBUTE(bank_fops, inj_bank_get, inj_bank_set, "%llu\n");

static const char readme_msg[] =
"Description of the files and their usages:\n"
"\n"
"Note1: i refers to the bank number below.\n"
"Note2: See respective BKDGs for the exact bit definitions of the files below\n"
"as they mirror the hardware registers.\n"
"\n"
"status:\t Set MCi_STATUS: the bits in that MSR control the error type and\n"
"\t attributes of the error which caused the MCE.\n"
"\n"
"misc:\t Set MCi_MISC: provide auxiliary info about the error. It is mostly\n"
"\t used for error thresholding purposes and its validity is indicated by\n"
"\t MCi_STATUS[MiscV].\n"
"\n"
"synd:\t Set MCi_SYND: provide syndrome info about the error. Only valid on\n"
"\t Scalable MCA systems, and its validity is indicated by MCi_STATUS[SyndV].\n"
"\n"
"addr:\t Error address value to be written to MCi_ADDR. Log address information\n"
"\t associated with the error.\n"
"\n"
"cpu:\t The CPU to inject the error on.\n"
"\n"
"bank:\t Specify the bank you want to inject the error into: the number of\n"
"\t banks in a processor varies and is family/model-specific, therefore, the\n"
"\t supplied value is sanity-checked. Setting the bank value also triggers the\n"
"\t injection.\n"
"\n"
"flags:\t Injection type to be performed. Writing to this file will trigger a\n"
"\t real machine check, an APIC interrupt or invoke the error decoder routines\n"
"\t for AMD processors.\n"
"\n"
"\t Allowed error injection types:\n"
"\t  - \"sw\": Software error injection. Decode error to a human-readable \n"
"\t    format only. Safe to use.\n"
"\t  - \"hw\": Hardware error injection. Causes the #MC exception handler to \n"
"\t    handle the error. Be warned: might cause system panic if MCi_STATUS[PCC] \n"
"\t    is set. Therefore, consider setting (debugfs_mountpoint)/mce/fake_panic \n"
"\t    before injecting.\n"
"\t  - \"df\": Trigger APIC interrupt for Deferred error. Causes deferred \n"
"\t    error APIC interrupt handler to handle the error if the feature is \n"
"\t    is present in hardware. \n"
"\t  - \"th\": Trigger APIC interrupt for Threshold errors. Causes threshold \n"
"\t    APIC interrupt handler to handle the error. \n"
"\n";

static ssize_t
inj_readme_read(struct file *filp, char __user *ubuf,
		       size_t cnt, loff_t *ppos)
{
	return simple_read_from_buffer(ubuf, cnt, ppos,
					readme_msg, strlen(readme_msg));
}

static const struct file_operations readme_fops = {
	.read		= inj_readme_read,
};

static struct dfs_node {
	char *name;
	struct dentry *d;
	const struct file_operations *fops;
	umode_t perm;
} dfs_fls[] = {
	{ .name = "status",	.fops = &status_fops, .perm = S_IRUSR | S_IWUSR },
	{ .name = "misc",	.fops = &misc_fops,   .perm = S_IRUSR | S_IWUSR },
	{ .name = "addr",	.fops = &addr_fops,   .perm = S_IRUSR | S_IWUSR },
	{ .name = "synd",	.fops = &synd_fops,   .perm = S_IRUSR | S_IWUSR },
	{ .name = "bank",	.fops = &bank_fops,   .perm = S_IRUSR | S_IWUSR },
	{ .name = "flags",	.fops = &flags_fops,  .perm = S_IRUSR | S_IWUSR },
	{ .name = "cpu",	.fops = &extcpu_fops, .perm = S_IRUSR | S_IWUSR },
	{ .name = "README",	.fops = &readme_fops, .perm = S_IRUSR | S_IRGRP | S_IROTH },
};

static int __init debugfs_init(void)
{
	unsigned int i;

	dfs_inj = debugfs_create_dir("mce-inject", NULL);
	if (!dfs_inj)
		return -EINVAL;

	for (i = 0; i < ARRAY_SIZE(dfs_fls); i++) {
		dfs_fls[i].d = debugfs_create_file(dfs_fls[i].name,
						    dfs_fls[i].perm,
						    dfs_inj,
						    &i_mce,
						    dfs_fls[i].fops);

		if (!dfs_fls[i].d)
			goto err_dfs_add;
	}

	return 0;

err_dfs_add:
	while (i-- > 0)
		debugfs_remove(dfs_fls[i].d);

	debugfs_remove(dfs_inj);
	dfs_inj = NULL;

	return -ENODEV;
}

static int __init inject_init(void)
{
	int err;

	if (!alloc_cpumask_var(&mce_inject_cpumask, GFP_KERNEL))
		return -ENOMEM;

	err = debugfs_init();
	if (err) {
		free_cpumask_var(mce_inject_cpumask);
		return err;
	}

	register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0, "mce_notify");
	mce_register_injector_chain(&inject_nb);

	setup_inj_struct(&i_mce);

	pr_info("Machine check injector initialized\n");

	return 0;
}

static void __exit inject_exit(void)
{

	mce_unregister_injector_chain(&inject_nb);
	unregister_nmi_handler(NMI_LOCAL, "mce_notify");

	debugfs_remove_recursive(dfs_inj);
	dfs_inj = NULL;

	memset(&dfs_fls, 0, sizeof(dfs_fls));

	free_cpumask_var(mce_inject_cpumask);
}

module_init(inject_init);
module_exit(inject_exit);
MODULE_LICENSE("GPL");