smmstore: Add a key/val store facility in flash, mediated through SMM

It exposes an interface that is as generic as possible, so payloads
and/or kernels can use it for their data.

Change-Id: I9553922f9dfa60b9d4b3576973ad4b84d3fe2fb5
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/25182
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 83 insertions, 0 deletions

diff --git a/src/drivers/smmstore/smi.c b/src/drivers/smmstore/smi.c
new file mode 100644
index 0000000000..3bcf564e1a
--- /dev/null
+++ b/src/drivers/smmstore/smi.c
@@ -0,0 +1,83 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2018 The Chromium OS Authors.  All rights reserved.
+ *
+ * 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 <console/console.h>
+#include <smmstore.h>
+#include <stddef.h>
+#include <stdint.h>
+
+/*
+ * Check that the given range is legal.
+ *
+ * Legal means:
+ *  - not pointing into SMRAM
+ *  - ...?
+ *
+ * returns 0 on success, -1 on failure
+ */
+static int range_check(void *start, size_t size)
+{
+	// TODO: fill in
+	return 0;
+}
+
+/* Param is usually EBX, ret in EAX */
+uint32_t smmstore_exec(uint8_t command, void *param)
+{
+	uint32_t ret = SMMSTORE_RET_FAILURE;
+
+	switch (command) {
+	case SMMSTORE_CMD_READ: {
+		printk(BIOS_DEBUG, "Reading from SMM store\n");
+		struct smmstore_params_read *params = param;
+
+		if (range_check(params->buf, params->bufsize) != 0)
+			break;
+
+		if (smmstore_read_region(params->buf, &params->bufsize) == 0)
+			ret = SMMSTORE_RET_SUCCESS;
+		break;
+	}
+
+	case SMMSTORE_CMD_APPEND: {
+		printk(BIOS_DEBUG, "Appending into SMM store\n");
+		struct smmstore_params_append *params = param;
+
+		if (range_check(params->key, params->keysize) != 0)
+			break;
+		if (range_check(params->val, params->valsize) != 0)
+			break;
+
+		if (smmstore_append_data(params->key, params->keysize,
+					 params->val, params->valsize) == 0)
+			ret = SMMSTORE_RET_SUCCESS;
+		break;
+	}
+
+	case SMMSTORE_CMD_CLEAR: {
+		if (smmstore_clear_region() == 0)
+			ret = SMMSTORE_RET_SUCCESS;
+		break;
+	}
+
+	default:
+		printk(BIOS_DEBUG,
+			"Unknown SMM store command: 0x%02x\n", command);
+		ret = SMMSTORE_RET_UNSUPPORTED;
+		break;
+	}
+
+	return ret;
+}