x86: qemu: add the ability to load and link ACPI tables from QEMU

This patch adds the ability to load and link ACPI tables provided by QEMU.
QEMU tells guests how to load and patch ACPI tables through its fw_cfg
interface, by adding a firmware file 'etc/table-loader'. Guests are
supposed to parse this file and execute corresponding QEMU commands.

Signed-off-by: Miao Yan <yanmiaobest@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/arch/x86/include/asm/fw_cfg.h b/arch/x86/include/asm/fw_cfg.h
index 2acf43eb81..e9450c6196 100644
--- a/arch/x86/include/asm/fw_cfg.h
+++ b/arch/x86/include/asm/fw_cfg.h
@@ -47,11 +47,23 @@ enum qemu_fwcfg_items {
 	FW_CFG_INVALID		= 0xffff,
 };
 
+enum {
+	BIOS_LINKER_LOADER_COMMAND_ALLOCATE	= 0x1,
+	BIOS_LINKER_LOADER_COMMAND_ADD_POINTER  = 0x2,
+	BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM = 0x3,
+};
+
+enum {
+	BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH = 0x1,
+	BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG = 0x2,
+};
+
 #define FW_CFG_FILE_SLOTS	0x10
 #define FW_CFG_MAX_ENTRY	(FW_CFG_FILE_FIRST + FW_CFG_FILE_SLOTS)
 #define FW_CFG_ENTRY_MASK	 ~(FW_CFG_WRITE_CHANNEL | FW_CFG_ARCH_LOCAL)
 
 #define FW_CFG_MAX_FILE_PATH	56
+#define BIOS_LINKER_LOADER_FILESZ FW_CFG_MAX_FILE_PATH
 
 #define QEMU_FW_CFG_SIGNATURE	(('Q' << 24) | ('E' << 16) | ('M' << 8) | 'U')
 
@@ -81,6 +93,55 @@ struct fw_cfg_dma_access {
 	__be64 address;
 };
 
+struct bios_linker_entry {
+	__le32 command;
+	union {
+		/*
+		 * COMMAND_ALLOCATE - allocate a table from @alloc.file
+		 * subject to @alloc.align alignment (must be power of 2)
+		 * and @alloc.zone (can be HIGH or FSEG) requirements.
+		 *
+		 * Must appear exactly once for each file, and before
+		 * this file is referenced by any other command.
+		 */
+		struct {
+			char file[BIOS_LINKER_LOADER_FILESZ];
+			__le32 align;
+			uint8_t zone;
+		} alloc;
+
+		/*
+		 * COMMAND_ADD_POINTER - patch the table (originating from
+		 * @dest_file) at @pointer.offset, by adding a pointer to the
+		 * table originating from @src_file. 1,2,4 or 8 byte unsigned
+		 * addition is used depending on @pointer.size.
+		 */
+		struct {
+			char dest_file[BIOS_LINKER_LOADER_FILESZ];
+			char src_file[BIOS_LINKER_LOADER_FILESZ];
+			__le32 offset;
+			uint8_t size;
+		} pointer;
+
+		/*
+		 * COMMAND_ADD_CHECKSUM - calculate checksum of the range
+		 * specified by @cksum_start and @cksum_length fields,
+		 * and then add the value at @cksum.offset.
+		 * Checksum simply sums -X for each byte X in the range
+		 * using 8-bit math.
+		 */
+		struct {
+			char file[BIOS_LINKER_LOADER_FILESZ];
+			__le32 offset;
+			__le32 start;
+			__le32 length;
+		} cksum;
+
+		/* padding */
+		char pad[124];
+	};
+} __packed;
+
 /**
  * Initialize QEMU fw_cfg interface
  */