drivers/mrc_cache: move mrc_cache support to drivers

There's nothing intel-specific about the current mrc_cache support.
It's logic manages saving non-volatile areas into the boot media.
Therefore, expose it to the rest of the system for any and all to
use.

BUG=b:69614064

Change-Id: I3b331c82a102f88912a3e10507a70207fb20aecc
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/22901
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

3 files changed, 628 insertions, 0 deletions

diff --git a/src/drivers/mrc_cache/Kconfig b/src/drivers/mrc_cache/Kconfig
new file mode 100644
index 0000000000..3e0bdda2be
--- /dev/null
+++ b/src/drivers/mrc_cache/Kconfig
@@ -0,0 +1,31 @@
+config CACHE_MRC_SETTINGS
+	bool "Save cached MRC settings"
+	default n
+
+if CACHE_MRC_SETTINGS
+
+config MRC_SETTINGS_CACHE_BASE
+	hex
+	default 0xfffe0000
+
+config MRC_SETTINGS_CACHE_SIZE
+	hex
+	default 0x10000
+
+config MRC_SETTINGS_PROTECT
+	bool "Enable protection on MRC settings"
+	default n
+
+config HAS_RECOVERY_MRC_CACHE
+	bool
+	default n
+
+config MRC_CLEAR_NORMAL_CACHE_ON_RECOVERY_RETRAIN
+	bool
+	default n
+
+config MRC_SETTINGS_VARIABLE_DATA
+	bool
+	default n
+
+endif # CACHE_MRC_SETTINGS
diff --git a/src/drivers/mrc_cache/Makefile.inc b/src/drivers/mrc_cache/Makefile.inc
new file mode 100644
index 0000000000..819d637e4f
--- /dev/null
+++ b/src/drivers/mrc_cache/Makefile.inc
@@ -0,0 +1,16 @@
+
+romstage-$(CONFIG_CACHE_MRC_SETTINGS) += mrc_cache.c
+ramstage-$(CONFIG_CACHE_MRC_SETTINGS) += mrc_cache.c
+
+# Create and add the MRC cache to the cbfs image
+ifneq ($(CONFIG_CHROMEOS),y)
+$(obj)/mrc.cache: $(obj)/config.h
+	dd if=/dev/zero count=1 \
+	bs=$(shell printf "%d" $(CONFIG_MRC_SETTINGS_CACHE_SIZE) ) | \
+	tr '\000' '\377' > $@
+
+cbfs-files-$(CONFIG_CACHE_MRC_SETTINGS) += mrc.cache
+mrc.cache-file := $(obj)/mrc.cache
+mrc.cache-position := $(CONFIG_MRC_SETTINGS_CACHE_BASE)
+mrc.cache-type := mrc_cache
+endif
diff --git a/src/drivers/mrc_cache/mrc_cache.c b/src/drivers/mrc_cache/mrc_cache.c
new file mode 100644
index 0000000000..3a9689645f
--- /dev/null
+++ b/src/drivers/mrc_cache/mrc_cache.c
@@ -0,0 +1,581 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2014 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <compiler.h>
+#include <string.h>
+#include <boot_device.h>
+#include <bootstate.h>
+#include <bootmode.h>
+#include <console/console.h>
+#include <cbmem.h>
+#include <elog.h>
+#include <fmap.h>
+#include <ip_checksum.h>
+#include <region_file.h>
+#include <security/vboot/vboot_common.h>
+#include <spi_flash.h>
+
+#include "mrc_cache.h"
+
+#define DEFAULT_MRC_CACHE	"RW_MRC_CACHE"
+#define VARIABLE_MRC_CACHE	"RW_VAR_MRC_CACHE"
+#define RECOVERY_MRC_CACHE	"RECOVERY_MRC_CACHE"
+#define UNIFIED_MRC_CACHE	"UNIFIED_MRC_CACHE"
+
+#define MRC_DATA_SIGNATURE       (('M'<<0)|('R'<<8)|('C'<<16)|('D'<<24))
+
+struct mrc_metadata {
+	uint32_t signature;
+	uint32_t data_size;
+	uint16_t data_checksum;
+	uint16_t header_checksum;
+	uint32_t version;
+} __packed;
+
+enum result {
+	UPDATE_FAILURE		= -1,
+	UPDATE_SUCCESS		= 0,
+	ALREADY_UPTODATE	= 1
+};
+
+#define NORMAL_FLAG (1 << 0)
+#define RECOVERY_FLAG (1 << 1)
+
+struct cache_region {
+	const char *name;
+	uint32_t cbmem_id;
+	int type;
+	int elog_slot;
+	int flags;
+};
+
+static const struct cache_region recovery_training = {
+	.name = RECOVERY_MRC_CACHE,
+	.cbmem_id = CBMEM_ID_MRCDATA,
+	.type = MRC_TRAINING_DATA,
+	.elog_slot = ELOG_MEM_CACHE_UPDATE_SLOT_RECOVERY,
+#if IS_ENABLED(CONFIG_HAS_RECOVERY_MRC_CACHE)
+	.flags = RECOVERY_FLAG,
+#else
+	.flags = 0,
+#endif
+};
+
+static const struct cache_region normal_training = {
+	.name = DEFAULT_MRC_CACHE,
+	.cbmem_id = CBMEM_ID_MRCDATA,
+	.type = MRC_TRAINING_DATA,
+	.elog_slot = ELOG_MEM_CACHE_UPDATE_SLOT_NORMAL,
+	.flags = NORMAL_FLAG | RECOVERY_FLAG,
+};
+
+static const struct cache_region variable_data = {
+	.name = VARIABLE_MRC_CACHE,
+	.cbmem_id = CBMEM_ID_VAR_MRCDATA,
+	.type = MRC_VARIABLE_DATA,
+	.elog_slot = ELOG_MEM_CACHE_UPDATE_SLOT_VARIABLE,
+	.flags = NORMAL_FLAG | RECOVERY_FLAG,
+};
+
+/* Order matters here for priority in matching. */
+static const struct cache_region *cache_regions[] = {
+	&recovery_training,
+	&normal_training,
+	&variable_data,
+};
+
+static int lookup_region_by_name(const char *name, struct region *r)
+{
+	/* This assumes memory mapped boot media just under 4GiB. */
+	const uint32_t pointer_base_32bit = -CONFIG_ROM_SIZE;
+
+	if (fmap_locate_area(name, r) == 0)
+		return 0;
+
+	/* CHROMEOS builds must get their MRC cache from FMAP. */
+	if (IS_ENABLED(CONFIG_CHROMEOS)) {
+		printk(BIOS_ERR, "MRC: Chrome OS lookup failure.\n");
+		return -1;
+	}
+
+	if (!IS_ENABLED(CONFIG_BOOT_DEVICE_MEMORY_MAPPED))
+		return -1;
+
+	/* Base is in the form of a pointer. Make it an offset. */
+	r->offset = CONFIG_MRC_SETTINGS_CACHE_BASE - pointer_base_32bit;
+	r->size = CONFIG_MRC_SETTINGS_CACHE_SIZE;
+
+	return 0;
+}
+
+static const struct cache_region *lookup_region_type(int type)
+{
+	int i;
+	int flags;
+
+	if (vboot_recovery_mode_enabled())
+		flags = RECOVERY_FLAG;
+	else
+		flags = NORMAL_FLAG;
+
+	for (i = 0; i < ARRAY_SIZE(cache_regions); i++) {
+		if (cache_regions[i]->type != type)
+			continue;
+		if ((cache_regions[i]->flags & flags) == flags)
+			return cache_regions[i];
+	}
+
+	return NULL;
+}
+
+int mrc_cache_stash_data(int type, uint32_t version, const void *data,
+			size_t size)
+{
+	const struct cache_region *cr;
+	size_t cbmem_size;
+	struct mrc_metadata *md;
+
+	cr = lookup_region_type(type);
+	if (cr == NULL) {
+		printk(BIOS_ERR, "MRC: failed to add to cbmem for type %d.\n",
+			type);
+		return -1;
+	}
+
+	cbmem_size = sizeof(*md) + size;
+
+	md = cbmem_add(cr->cbmem_id, cbmem_size);
+
+	if (md == NULL) {
+		printk(BIOS_ERR, "MRC: failed to add '%s' to cbmem.\n",
+			cr->name);
+		return -1;
+	}
+
+	memset(md, 0, sizeof(*md));
+	md->signature = MRC_DATA_SIGNATURE;
+	md->data_size = size;
+	md->version = version;
+	md->data_checksum = compute_ip_checksum(data, size);
+	md->header_checksum = compute_ip_checksum(md, sizeof(*md));
+	memcpy(&md[1], data, size);
+
+	return 0;
+}
+
+static const struct cache_region *lookup_region(struct region *r, int type)
+{
+	const struct cache_region *cr;
+
+	cr = lookup_region_type(type);
+
+	if (cr == NULL) {
+		printk(BIOS_ERR, "MRC: failed to locate region type %d.\n",
+			type);
+		return NULL;
+	}
+
+	if (lookup_region_by_name(cr->name, r) < 0)
+		return NULL;
+
+	return cr;
+}
+
+static int mrc_header_valid(struct region_device *rdev, struct mrc_metadata *md)
+{
+	uint16_t checksum;
+	uint16_t checksum_result;
+	size_t size;
+
+	if (rdev_readat(rdev, md, 0, sizeof(*md)) < 0) {
+		printk(BIOS_ERR, "MRC: couldn't read metadata\n");
+		return -1;
+	}
+
+	if (md->signature != MRC_DATA_SIGNATURE) {
+		printk(BIOS_ERR, "MRC: invalid header signature\n");
+		return -1;
+	}
+
+	/* Compute checksum over header with 0 as the value. */
+	checksum = md->header_checksum;
+	md->header_checksum = 0;
+	checksum_result = compute_ip_checksum(md, sizeof(*md));
+
+	if (checksum != checksum_result) {
+		printk(BIOS_ERR, "MRC: header checksum mismatch: %x vs %x\n",
+			checksum, checksum_result);
+		return -1;
+	}
+
+	/* Put back original. */
+	md->header_checksum = checksum;
+
+	/* Re-size the region device according to the metadata as a region_file
+	 * does block allocation. */
+	size = sizeof(*md) + md->data_size;
+	if (rdev_chain(rdev, rdev, 0, size) < 0) {
+		printk(BIOS_ERR, "MRC: size exceeds rdev size: %zx vs %zx\n",
+			size, region_device_sz(rdev));
+		return -1;
+	}
+
+	return 0;
+}
+
+static int mrc_data_valid(const struct region_device *rdev,
+				const struct mrc_metadata *md)
+{
+	void *data;
+	uint16_t checksum;
+	const size_t md_size = sizeof(*md);
+	const size_t data_size = md->data_size;
+
+	data = rdev_mmap(rdev, md_size, data_size);
+	if (data == NULL) {
+		printk(BIOS_ERR, "MRC: mmap failure on data verification.\n");
+		return -1;
+	}
+
+	checksum = compute_ip_checksum(data, data_size);
+
+	rdev_munmap(rdev, data);
+	if (md->data_checksum != checksum) {
+		printk(BIOS_ERR, "MRC: data checksum mismatch: %x vs %x\n",
+			md->data_checksum, checksum);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int mrc_cache_latest(const char *name,
+				const struct region_device *backing_rdev,
+				struct mrc_metadata *md,
+				struct region_file *cache_file,
+				struct region_device *rdev,
+				bool fail_bad_data)
+{
+	/* Init and obtain a handle to the file data. */
+	if (region_file_init(cache_file, backing_rdev) < 0) {
+		printk(BIOS_ERR, "MRC: region file invalid in '%s'\n", name);
+		return -1;
+	}
+
+	/* Provide a 0 sized region_device from here on out so the caller
+	 * has a valid yet unusable region_device. */
+	rdev_chain(rdev, backing_rdev, 0, 0);
+
+	/* No data to return. */
+	if (region_file_data(cache_file, rdev) < 0) {
+		printk(BIOS_ERR, "MRC: no data in '%s'\n", name);
+		return fail_bad_data ? -1 : 0;
+	}
+
+	/* Validate header and resize region to reflect actual usage on the
+	 * saved medium (including metadata and data). */
+	if (mrc_header_valid(rdev, md) < 0) {
+		printk(BIOS_ERR, "MRC: invalid header in '%s'\n", name);
+		return fail_bad_data ? -1 : 0;
+	}
+
+	/* Validate Data */
+	if (mrc_data_valid(rdev, md) < 0) {
+		printk(BIOS_ERR, "MRC: invalid data in '%s'\n", name);
+		return fail_bad_data ? -1 : 0;
+	}
+
+	return 0;
+}
+
+int mrc_cache_get_current(int type, uint32_t version,
+				struct region_device *rdev)
+{
+	const struct cache_region *cr;
+	struct region region;
+	struct region_device read_rdev;
+	struct region_file cache_file;
+	struct mrc_metadata md;
+	size_t data_size;
+	const size_t md_size = sizeof(md);
+	const bool fail_bad_data = true;
+
+	cr = lookup_region(&region, type);
+
+	if (cr == NULL)
+		return -1;
+
+	if (boot_device_ro_subregion(&region, &read_rdev) < 0)
+		return -1;
+
+	if (mrc_cache_latest(cr->name, &read_rdev, &md, &cache_file, rdev,
+		fail_bad_data) < 0)
+		return -1;
+
+	if (version != md.version) {
+		printk(BIOS_INFO, "MRC: version mismatch: %x vs %x\n",
+			md.version, version);
+		return -1;
+	}
+
+	/* Re-size rdev to only contain the data. i.e. remove metadata. */
+	data_size = md.data_size;
+	return rdev_chain(rdev, rdev, md_size, data_size);
+}
+
+static bool mrc_cache_needs_update(const struct region_device *rdev,
+				const struct cbmem_entry *to_be_updated)
+{
+	void *mapping;
+	size_t size = region_device_sz(rdev);
+	bool need_update = false;
+
+	if (cbmem_entry_size(to_be_updated) != size)
+		return true;
+
+	mapping = rdev_mmap_full(rdev);
+
+	if (memcmp(cbmem_entry_start(to_be_updated), mapping, size))
+		need_update = true;
+
+	rdev_munmap(rdev, mapping);
+
+	return need_update;
+}
+
+static void log_event_cache_update(uint8_t slot, enum result res)
+{
+	const int type = ELOG_TYPE_MEM_CACHE_UPDATE;
+	struct elog_event_mem_cache_update event = {
+		.slot = slot
+	};
+
+	/* Filter through interesting events only */
+	switch (res) {
+	case UPDATE_FAILURE:
+		event.status = ELOG_MEM_CACHE_UPDATE_STATUS_FAIL;
+		break;
+	case UPDATE_SUCCESS:
+		event.status = ELOG_MEM_CACHE_UPDATE_STATUS_SUCCESS;
+		break;
+	default:
+		return;
+	}
+
+	if (elog_add_event_raw(type, &event, sizeof(event)) < 0)
+		printk(BIOS_ERR, "Failed to log mem cache update event.\n");
+}
+
+/* During ramstage this code purposefully uses incoherent transactions between
+ * read and write. The read assumes a memory-mapped boot device that can be used
+ * to quickly locate and compare the up-to-date data. However, when an update
+ * is required it uses the writeable region access to perform the update. */
+static void update_mrc_cache_by_type(int type)
+{
+	const struct cache_region *cr;
+	struct region region;
+	struct region_device read_rdev;
+	struct region_device write_rdev;
+	struct region_file cache_file;
+	struct mrc_metadata md;
+	const struct cbmem_entry *to_be_updated;
+	struct incoherent_rdev backing_irdev;
+	const struct region_device *backing_rdev;
+	struct region_device latest_rdev;
+	const bool fail_bad_data = false;
+
+	cr = lookup_region(&region, type);
+
+	if (cr == NULL)
+		return;
+
+	to_be_updated = cbmem_entry_find(cr->cbmem_id);
+	if (to_be_updated == NULL) {
+		printk(BIOS_ERR, "MRC: No data in cbmem for '%s'.\n",
+			cr->name);
+		return;
+	}
+
+	printk(BIOS_DEBUG, "MRC: Checking cached data update for '%s'.\n",
+		cr->name);
+
+	if (boot_device_ro_subregion(&region, &read_rdev) < 0)
+		return;
+
+	if (boot_device_rw_subregion(&region, &write_rdev) < 0)
+		return;
+
+	backing_rdev = incoherent_rdev_init(&backing_irdev, &region, &read_rdev,
+						&write_rdev);
+
+	if (backing_rdev == NULL)
+		return;
+
+	if (mrc_cache_latest(cr->name, backing_rdev, &md, &cache_file,
+		&latest_rdev, fail_bad_data) < 0)
+		return;
+
+	if (!mrc_cache_needs_update(&latest_rdev, to_be_updated)) {
+		log_event_cache_update(cr->elog_slot, ALREADY_UPTODATE);
+		return;
+	}
+
+	printk(BIOS_DEBUG, "MRC: cache data '%s' needs update.\n", cr->name);
+
+	if (region_file_update_data(&cache_file,
+		cbmem_entry_start(to_be_updated),
+		cbmem_entry_size(to_be_updated)) < 0)
+		log_event_cache_update(cr->elog_slot, UPDATE_FAILURE);
+	else
+		log_event_cache_update(cr->elog_slot, UPDATE_SUCCESS);
+}
+
+/* Read flash status register to determine if write protect is active */
+static int nvm_is_write_protected(void)
+{
+	u8 sr1;
+	u8 wp_gpio;
+	u8 wp_spi;
+
+	if (!IS_ENABLED(CONFIG_CHROMEOS))
+		return 0;
+
+	if (!IS_ENABLED(CONFIG_BOOT_DEVICE_SPI_FLASH))
+		return 0;
+
+	/* Read Write Protect GPIO if available */
+	wp_gpio = get_write_protect_state();
+
+	/* Read Status Register 1 */
+	if (spi_flash_status(boot_device_spi_flash(), &sr1) < 0) {
+		printk(BIOS_ERR, "Failed to read SPI status register 1\n");
+		return -1;
+	}
+	wp_spi = !!(sr1 & 0x80);
+
+	printk(BIOS_DEBUG, "SPI flash protection: WPSW=%d SRP0=%d\n",
+		wp_gpio, wp_spi);
+
+	return wp_gpio && wp_spi;
+}
+
+/* Apply protection to a range of flash */
+static int nvm_protect(const struct region *r)
+{
+	if (!IS_ENABLED(CONFIG_MRC_SETTINGS_PROTECT))
+		return 0;
+
+	if (!IS_ENABLED(CONFIG_BOOT_DEVICE_SPI_FLASH))
+		return 0;
+
+	return spi_flash_ctrlr_protect_region(boot_device_spi_flash(), r);
+}
+
+/* Protect mrc region with a Protected Range Register */
+static int protect_mrc_cache(const char *name)
+{
+	struct region region;
+
+	if (!IS_ENABLED(CONFIG_MRC_SETTINGS_PROTECT))
+		return 0;
+
+	if (lookup_region_by_name(name, &region) < 0) {
+		printk(BIOS_ERR, "MRC: Could not find region '%s'\n", name);
+		return -1;
+	}
+
+	if (nvm_is_write_protected() <= 0) {
+		printk(BIOS_INFO, "MRC: NOT enabling PRR for '%s'.\n", name);
+		return 0;
+	}
+
+	if (nvm_protect(&region) < 0) {
+		printk(BIOS_ERR, "MRC: ERROR setting PRR for '%s'.\n", name);
+		return -1;
+	}
+
+	printk(BIOS_INFO, "MRC: Enabled Protected Range on '%s'.\n", name);
+	return 0;
+}
+
+static void protect_mrc_region(void)
+{
+	/*
+	 * Check if there is a single unified region that encompasses both
+	 * RECOVERY_MRC_CACHE and DEFAULT_MRC_CACHE. In that case protect the
+	 * entire region using a single PRR.
+	 *
+	 * If we are not able to protect the entire region, try protecting
+	 * individual regions next.
+	 */
+	if (protect_mrc_cache(UNIFIED_MRC_CACHE) == 0)
+		return;
+
+	if (IS_ENABLED(CONFIG_HAS_RECOVERY_MRC_CACHE))
+		protect_mrc_cache(RECOVERY_MRC_CACHE);
+
+	protect_mrc_cache(DEFAULT_MRC_CACHE);
+}
+
+static void invalidate_normal_cache(void)
+{
+	struct region_file cache_file;
+	struct region_device rdev;
+	const char *name = DEFAULT_MRC_CACHE;
+	const uint32_t invalid = ~MRC_DATA_SIGNATURE;
+
+	/* Invalidate only on recovery mode with retraining enabled. */
+	if (!vboot_recovery_mode_enabled())
+		return;
+	if (!vboot_recovery_mode_memory_retrain())
+		return;
+
+	if (fmap_locate_area_as_rdev_rw(name, &rdev) < 0) {
+		printk(BIOS_ERR, "MRC: Couldn't find '%s' region. Invalidation failed\n",
+			name);
+		return;
+	}
+
+	if (region_file_init(&cache_file, &rdev) < 0) {
+		printk(BIOS_ERR, "MRC: region file invalid for '%s'. Invalidation failed\n",
+			name);
+		return;
+	}
+
+	/* Push an update that consists of 4 bytes that is smaller than the
+	 * MRC metadata as well as an invalid signature. */
+	if (region_file_update_data(&cache_file, &invalid, sizeof(invalid)) < 0)
+		printk(BIOS_ERR, "MRC: invalidation failed for '%s'.\n", name);
+}
+
+static void update_mrc_cache(void *unused)
+{
+	update_mrc_cache_by_type(MRC_TRAINING_DATA);
+
+	if (IS_ENABLED(CONFIG_MRC_SETTINGS_VARIABLE_DATA))
+		update_mrc_cache_by_type(MRC_VARIABLE_DATA);
+
+	if (IS_ENABLED(CONFIG_MRC_CLEAR_NORMAL_CACHE_ON_RECOVERY_RETRAIN))
+		invalidate_normal_cache();
+
+	protect_mrc_region();
+}
+
+/*
+ * Ensures MRC training data is stored into SPI after PCI enumeration is done
+ * during BS_DEV_ENUMERATE-BS_ON_EXIT and lock down SPI protected ranges
+ * during BS_DEV_RESOURCES-BS_ON_EXIT.
+ */
+BOOT_STATE_INIT_ENTRY(BS_DEV_ENUMERATE, BS_ON_EXIT, update_mrc_cache, NULL);