soc/amd/common/psp_smi_flash: validate target SPI region ID

Add and use functions to validate the target non-volatile storage ID in
the different command buffer structs.

This patch is a slightly reworked version of parts of CB:65523.

Document #55758 Rev. 2.04 was used as a reference.

Test=When selecting SOC_AMD_COMMON_BLOCK_PSP_SMI, Mandolin still builds

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Signed-off-by: Ritul Guru <ritul.bits@gmail.com>
Change-Id: Idda0166c862d41d380b2ed21345eead5e0a1c135
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83758
Reviewed-by: Martin Roth <martin.roth@amd.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/common/block/psp/psp_smi_flash.c

@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
 #include <console/console.h>
+#include <device/mmio.h>
 #include <types.h>
 #include "psp_def.h"
 
@@ -45,30 +46,75 @@ struct mbox_pspv2_cmd_spi_erase {
 	struct pspv2_spi_erase_request req;
 } __packed;
 
+static bool is_valid_psp_spi_id(u64 target_nv_id)
+{
+	return target_nv_id == SMI_TARGET_NVRAM ||
+	       target_nv_id == SMI_TARGET_RPMC_NVRAM;
+}
+
+static bool is_valid_psp_spi_info(struct mbox_pspv2_cmd_spi_info *cmd_buf)
+{
+	return is_valid_psp_spi_id(read64(&cmd_buf->req.target_nv_id));
+}
+
+static bool is_valid_psp_spi_read_write(struct mbox_pspv2_cmd_spi_read_write *cmd_buf)
+{
+	return is_valid_psp_spi_id(read64(&cmd_buf->req.target_nv_id));
+}
+
+static bool is_valid_psp_spi_erase(struct mbox_pspv2_cmd_spi_erase *cmd_buf)
+{
+	return is_valid_psp_spi_id(read64(&cmd_buf->req.target_nv_id));
+}
+
 enum mbox_p2c_status psp_smi_spi_get_info(struct mbox_default_buffer *buffer)
 {
+	struct mbox_pspv2_cmd_spi_info *const cmd_buf =
+		(struct mbox_pspv2_cmd_spi_info *)buffer;
+
 	printk(BIOS_SPEW, "PSP: SPI info request\n");
 
+	if (!is_valid_psp_spi_info(cmd_buf))
+		return MBOX_PSP_COMMAND_PROCESS_ERROR;
+
 	return MBOX_PSP_UNSUPPORTED;
 }
 
 enum mbox_p2c_status psp_smi_spi_read(struct mbox_default_buffer *buffer)
 {
+	struct mbox_pspv2_cmd_spi_read_write *const cmd_buf =
+		(struct mbox_pspv2_cmd_spi_read_write *)buffer;
+
 	printk(BIOS_SPEW, "PSP: SPI read request\n");
 
+	if (!is_valid_psp_spi_read_write(cmd_buf))
+		return MBOX_PSP_COMMAND_PROCESS_ERROR;
+
 	return MBOX_PSP_UNSUPPORTED;
 }
 
 enum mbox_p2c_status psp_smi_spi_write(struct mbox_default_buffer *buffer)
 {
+	struct mbox_pspv2_cmd_spi_read_write *const cmd_buf =
+		(struct mbox_pspv2_cmd_spi_read_write *)buffer;
+
 	printk(BIOS_SPEW, "PSP: SPI write request\n");
 
+	if (!is_valid_psp_spi_read_write(cmd_buf))
+		return MBOX_PSP_COMMAND_PROCESS_ERROR;
+
 	return MBOX_PSP_UNSUPPORTED;
 }
 
 enum mbox_p2c_status psp_smi_spi_erase(struct mbox_default_buffer *buffer)
 {
+	struct mbox_pspv2_cmd_spi_erase *const cmd_buf =
+		(struct mbox_pspv2_cmd_spi_erase *)buffer;
+
 	printk(BIOS_SPEW, "PSP: SPI erase request\n");
 
+	if (!is_valid_psp_spi_erase(cmd_buf))
+		return MBOX_PSP_COMMAND_PROCESS_ERROR;
+
 	return MBOX_PSP_UNSUPPORTED;
 }