x86: Add multi-processor init

Most modern x86 CPUs include more than one CPU core. The OS normally requires
that these 'Application Processors' (APs) be brought up by the boot loader.
Add the required support to U-Boot to init additional APs.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

1 files changed, 496 insertions, 0 deletions

diff --git a/arch/x86/cpu/mp_init.c b/arch/x86/cpu/mp_init.c
new file mode 100644
index 0000000000..ac5753a1fd
--- /dev/null
+++ b/arch/x86/cpu/mp_init.c
@@ -0,0 +1,496 @@
+/*
+ * Copyright (C) 2015 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ *
+ * Based on code from the coreboot file of the same name
+ */
+
+#include <common.h>
+#include <cpu.h>
+#include <dm.h>
+#include <errno.h>
+#include <malloc.h>
+#include <asm/atomic.h>
+#include <asm/cpu.h>
+#include <asm/interrupt.h>
+#include <asm/lapic.h>
+#include <asm/mp.h>
+#include <asm/mtrr.h>
+#include <asm/sipi.h>
+#include <dm/device-internal.h>
+#include <dm/uclass-internal.h>
+#include <linux/linkage.h>
+
+/* This also needs to match the sipi.S assembly code for saved MSR encoding */
+struct saved_msr {
+	uint32_t index;
+	uint32_t lo;
+	uint32_t hi;
+} __packed;
+
+
+struct mp_flight_plan {
+	int num_records;
+	struct mp_flight_record *records;
+};
+
+static struct mp_flight_plan mp_info;
+
+struct cpu_map {
+	struct udevice *dev;
+	int apic_id;
+	int err_code;
+};
+
+static inline void barrier_wait(atomic_t *b)
+{
+	while (atomic_read(b) == 0)
+		asm("pause");
+	mfence();
+}
+
+static inline void release_barrier(atomic_t *b)
+{
+	mfence();
+	atomic_set(b, 1);
+}
+
+/* Returns 1 if timeout waiting for APs. 0 if target APs found */
+static int wait_for_aps(atomic_t *val, int target, int total_delay,
+			int delay_step)
+{
+	int timeout = 0;
+	int delayed = 0;
+
+	while (atomic_read(val) != target) {
+		udelay(delay_step);
+		delayed += delay_step;
+		if (delayed >= total_delay) {
+			timeout = 1;
+			break;
+		}
+	}
+
+	return timeout;
+}
+
+static void ap_do_flight_plan(struct udevice *cpu)
+{
+	int i;
+
+	for (i = 0; i < mp_info.num_records; i++) {
+		struct mp_flight_record *rec = &mp_info.records[i];
+
+		atomic_inc(&rec->cpus_entered);
+		barrier_wait(&rec->barrier);
+
+		if (rec->ap_call != NULL)
+			rec->ap_call(cpu, rec->ap_arg);
+	}
+}
+
+static int find_cpu_by_apid_id(int apic_id, struct udevice **devp)
+{
+	struct udevice *dev;
+
+	*devp = NULL;
+	for (uclass_find_first_device(UCLASS_CPU, &dev);
+	     dev;
+	     uclass_find_next_device(&dev)) {
+		struct cpu_platdata *plat = dev_get_parent_platdata(dev);
+
+		if (plat->cpu_id == apic_id) {
+			*devp = dev;
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
+
+/*
+ * By the time APs call ap_init() caching has been setup, and microcode has
+ * been loaded
+ */
+static void ap_init(unsigned int cpu_index)
+{
+	struct udevice *dev;
+	int apic_id;
+	int ret;
+
+	/* Ensure the local apic is enabled */
+	enable_lapic();
+
+	apic_id = lapicid();
+	ret = find_cpu_by_apid_id(apic_id, &dev);
+	if (ret) {
+		debug("Unknown CPU apic_id %x\n", apic_id);
+		goto done;
+	}
+
+	debug("AP: slot %d apic_id %x, dev %s\n", cpu_index, apic_id,
+	      dev ? dev->name : "(apic_id not found)");
+
+	/* Walk the flight plan */
+	ap_do_flight_plan(dev);
+
+	/* Park the AP */
+	debug("parking\n");
+done:
+	stop_this_cpu();
+}
+
+static const unsigned int fixed_mtrrs[NUM_FIXED_MTRRS] = {
+	MTRR_FIX_64K_00000_MSR, MTRR_FIX_16K_80000_MSR, MTRR_FIX_16K_A0000_MSR,
+	MTRR_FIX_4K_C0000_MSR, MTRR_FIX_4K_C8000_MSR, MTRR_FIX_4K_D0000_MSR,
+	MTRR_FIX_4K_D8000_MSR, MTRR_FIX_4K_E0000_MSR, MTRR_FIX_4K_E8000_MSR,
+	MTRR_FIX_4K_F0000_MSR, MTRR_FIX_4K_F8000_MSR,
+};
+
+static inline struct saved_msr *save_msr(int index, struct saved_msr *entry)
+{
+	msr_t msr;
+
+	msr = msr_read(index);
+	entry->index = index;
+	entry->lo = msr.lo;
+	entry->hi = msr.hi;
+
+	/* Return the next entry */
+	entry++;
+	return entry;
+}
+
+static int save_bsp_msrs(char *start, int size)
+{
+	int msr_count;
+	int num_var_mtrrs;
+	struct saved_msr *msr_entry;
+	int i;
+	msr_t msr;
+
+	/* Determine number of MTRRs need to be saved */
+	msr = msr_read(MTRR_CAP_MSR);
+	num_var_mtrrs = msr.lo & 0xff;
+
+	/* 2 * num_var_mtrrs for base and mask. +1 for IA32_MTRR_DEF_TYPE */
+	msr_count = 2 * num_var_mtrrs + NUM_FIXED_MTRRS + 1;
+
+	if ((msr_count * sizeof(struct saved_msr)) > size) {
+		printf("Cannot mirror all %d msrs.\n", msr_count);
+		return -ENOSPC;
+	}
+
+	msr_entry = (void *)start;
+	for (i = 0; i < NUM_FIXED_MTRRS; i++)
+		msr_entry = save_msr(fixed_mtrrs[i], msr_entry);
+
+	for (i = 0; i < num_var_mtrrs; i++) {
+		msr_entry = save_msr(MTRR_PHYS_BASE_MSR(i), msr_entry);
+		msr_entry = save_msr(MTRR_PHYS_MASK_MSR(i), msr_entry);
+	}
+
+	msr_entry = save_msr(MTRR_DEF_TYPE_MSR, msr_entry);
+
+	return msr_count;
+}
+
+static int load_sipi_vector(atomic_t **ap_countp)
+{
+	struct sipi_params_16bit *params16;
+	struct sipi_params *params;
+	static char msr_save[512];
+	char *stack;
+	ulong addr;
+	int code_len;
+	int size;
+	int ret;
+
+	/* Copy in the code */
+	code_len = ap_start16_code_end - ap_start16;
+	debug("Copying SIPI code to %x: %d bytes\n", AP_DEFAULT_BASE,
+	      code_len);
+	memcpy((void *)AP_DEFAULT_BASE, ap_start16, code_len);
+
+	addr = AP_DEFAULT_BASE + (ulong)sipi_params_16bit - (ulong)ap_start16;
+	params16 = (struct sipi_params_16bit *)addr;
+	params16->ap_start = (uint32_t)ap_start;
+	params16->gdt = (uint32_t)gd->arch.gdt;
+	params16->gdt_limit = X86_GDT_SIZE - 1;
+	debug("gdt = %x, gdt_limit = %x\n", params16->gdt, params16->gdt_limit);
+
+	params = (struct sipi_params *)sipi_params;
+	debug("SIPI 32-bit params at %p\n", params);
+	params->idt_ptr = (uint32_t)x86_get_idt();
+
+	params->stack_size = CONFIG_AP_STACK_SIZE;
+	size = params->stack_size * CONFIG_MAX_CPUS;
+	stack = memalign(size, 4096);
+	if (!stack)
+		return -ENOMEM;
+	params->stack_top = (u32)(stack + size);
+
+	params->microcode_ptr = 0;
+	params->msr_table_ptr = (u32)msr_save;
+	ret = save_bsp_msrs(msr_save, sizeof(msr_save));
+	if (ret < 0)
+		return ret;
+	params->msr_count = ret;
+
+	params->c_handler = (uint32_t)&ap_init;
+
+	*ap_countp = &params->ap_count;
+	atomic_set(*ap_countp, 0);
+	debug("SIPI vector is ready\n");
+
+	return 0;
+}
+
+static int check_cpu_devices(int expected_cpus)
+{
+	int i;
+
+	for (i = 0; i < expected_cpus; i++) {
+		struct udevice *dev;
+		int ret;
+
+		ret = uclass_find_device(UCLASS_CPU, i, &dev);
+		if (ret) {
+			debug("Cannot find CPU %d in device tree\n", i);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+/* Returns 1 for timeout. 0 on success */
+static int apic_wait_timeout(int total_delay, int delay_step)
+{
+	int total = 0;
+	int timeout = 0;
+
+	while (lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY) {
+		udelay(delay_step);
+		total += delay_step;
+		if (total >= total_delay) {
+			timeout = 1;
+			break;
+		}
+	}
+
+	return timeout;
+}
+
+static int start_aps(int ap_count, atomic_t *num_aps)
+{
+	int sipi_vector;
+	/* Max location is 4KiB below 1MiB */
+	const int max_vector_loc = ((1 << 20) - (1 << 12)) >> 12;
+
+	if (ap_count == 0)
+		return 0;
+
+	/* The vector is sent as a 4k aligned address in one byte */
+	sipi_vector = AP_DEFAULT_BASE >> 12;
+
+	if (sipi_vector > max_vector_loc) {
+		printf("SIPI vector too large! 0x%08x\n",
+		       sipi_vector);
+		return -1;
+	}
+
+	debug("Attempting to start %d APs\n", ap_count);
+
+	if ((lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY)) {
+		debug("Waiting for ICR not to be busy...");
+		if (apic_wait_timeout(1000, 50)) {
+			debug("timed out. Aborting.\n");
+			return -1;
+		} else {
+			debug("done.\n");
+		}
+	}
+
+	/* Send INIT IPI to all but self */
+	lapic_write_around(LAPIC_ICR2, SET_LAPIC_DEST_FIELD(0));
+	lapic_write_around(LAPIC_ICR, LAPIC_DEST_ALLBUT | LAPIC_INT_ASSERT |
+			   LAPIC_DM_INIT);
+	debug("Waiting for 10ms after sending INIT.\n");
+	mdelay(10);
+
+	/* Send 1st SIPI */
+	if ((lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY)) {
+		debug("Waiting for ICR not to be busy...");
+		if (apic_wait_timeout(1000, 50)) {
+			debug("timed out. Aborting.\n");
+			return -1;
+		} else {
+			debug("done.\n");
+		}
+	}
+
+	lapic_write_around(LAPIC_ICR2, SET_LAPIC_DEST_FIELD(0));
+	lapic_write_around(LAPIC_ICR, LAPIC_DEST_ALLBUT | LAPIC_INT_ASSERT |
+			   LAPIC_DM_STARTUP | sipi_vector);
+	debug("Waiting for 1st SIPI to complete...");
+	if (apic_wait_timeout(10000, 50)) {
+		debug("timed out.\n");
+		return -1;
+	} else {
+		debug("done.\n");
+	}
+
+	/* Wait for CPUs to check in up to 200 us */
+	wait_for_aps(num_aps, ap_count, 200, 15);
+
+	/* Send 2nd SIPI */
+	if ((lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY)) {
+		debug("Waiting for ICR not to be busy...");
+		if (apic_wait_timeout(1000, 50)) {
+			debug("timed out. Aborting.\n");
+			return -1;
+		} else {
+			debug("done.\n");
+		}
+	}
+
+	lapic_write_around(LAPIC_ICR2, SET_LAPIC_DEST_FIELD(0));
+	lapic_write_around(LAPIC_ICR, LAPIC_DEST_ALLBUT | LAPIC_INT_ASSERT |
+			   LAPIC_DM_STARTUP | sipi_vector);
+	debug("Waiting for 2nd SIPI to complete...");
+	if (apic_wait_timeout(10000, 50)) {
+		debug("timed out.\n");
+		return -1;
+	} else {
+		debug("done.\n");
+	}
+
+	/* Wait for CPUs to check in */
+	if (wait_for_aps(num_aps, ap_count, 10000, 50)) {
+		debug("Not all APs checked in: %d/%d.\n",
+		      atomic_read(num_aps), ap_count);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int bsp_do_flight_plan(struct udevice *cpu, struct mp_params *mp_params)
+{
+	int i;
+	int ret = 0;
+	const int timeout_us = 100000;
+	const int step_us = 100;
+	int num_aps = mp_params->num_cpus - 1;
+
+	for (i = 0; i < mp_params->num_records; i++) {
+		struct mp_flight_record *rec = &mp_params->flight_plan[i];
+
+		/* Wait for APs if the record is not released */
+		if (atomic_read(&rec->barrier) == 0) {
+			/* Wait for the APs to check in */
+			if (wait_for_aps(&rec->cpus_entered, num_aps,
+					 timeout_us, step_us)) {
+				debug("MP record %d timeout.\n", i);
+				ret = -1;
+			}
+		}
+
+		if (rec->bsp_call != NULL)
+			rec->bsp_call(cpu, rec->bsp_arg);
+
+		release_barrier(&rec->barrier);
+	}
+	return ret;
+}
+
+static int init_bsp(struct udevice **devp)
+{
+	char processor_name[CPU_MAX_NAME_LEN];
+	int apic_id;
+	int ret;
+
+	cpu_get_name(processor_name);
+	debug("CPU: %s.\n", processor_name);
+
+	enable_lapic();
+
+	apic_id = lapicid();
+	ret = find_cpu_by_apid_id(apic_id, devp);
+	if (ret) {
+		printf("Cannot find boot CPU, APIC ID %d\n", apic_id);
+		return ret;
+	}
+
+	return 0;
+}
+
+int mp_init(struct mp_params *p)
+{
+	int num_aps;
+	atomic_t *ap_count;
+	struct udevice *cpu;
+	int ret;
+
+	/* This will cause the CPUs devices to be bound */
+	struct uclass *uc;
+	ret = uclass_get(UCLASS_CPU, &uc);
+	if (ret)
+		return ret;
+
+	ret = init_bsp(&cpu);
+	if (ret) {
+		debug("Cannot init boot CPU: err=%d\n", ret);
+		return ret;
+	}
+
+	if (p == NULL || p->flight_plan == NULL || p->num_records < 1) {
+		printf("Invalid MP parameters\n");
+		return -1;
+	}
+
+	ret = check_cpu_devices(p->num_cpus);
+	if (ret)
+		debug("Warning: Device tree does not describe all CPUs. Extra ones will not be started correctly\n");
+
+	/* Copy needed parameters so that APs have a reference to the plan */
+	mp_info.num_records = p->num_records;
+	mp_info.records = p->flight_plan;
+
+	/* Load the SIPI vector */
+	ret = load_sipi_vector(&ap_count);
+	if (ap_count == NULL)
+		return -1;
+
+	/*
+	 * Make sure SIPI data hits RAM so the APs that come up will see
+	 * the startup code even if the caches are disabled
+	 */
+	wbinvd();
+
+	/* Start the APs providing number of APs and the cpus_entered field */
+	num_aps = p->num_cpus - 1;
+	ret = start_aps(num_aps, ap_count);
+	if (ret) {
+		mdelay(1000);
+		debug("%d/%d eventually checked in?\n", atomic_read(ap_count),
+		      num_aps);
+		return ret;
+	}
+
+	/* Walk the flight plan for the BSP */
+	ret = bsp_do_flight_plan(cpu, p);
+	if (ret) {
+		debug("CPU init failed: err=%d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+int mp_init_cpu(struct udevice *cpu, void *unused)
+{
+	return device_probe(cpu);
+}