[U-Boot] [PATCH v2 4/4] x86: qemu: add the ability to load and link ACPI tables from QEMU

Miao Yan yanmiaobest at gmail.com
Wed Jan 20 05:24:25 CET 2016


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 at gmail.com>
---
Changes in v2:
  - add function comment
  - improve error handling

 arch/x86/cpu/qemu/fw_cfg.c    | 253 ++++++++++++++++++++++++++++++++++++++++++
 arch/x86/include/asm/fw_cfg.h |  61 ++++++++++
 arch/x86/lib/acpi_table.c     |   4 +
 3 files changed, 318 insertions(+)

diff --git a/arch/x86/cpu/qemu/fw_cfg.c b/arch/x86/cpu/qemu/fw_cfg.c
index bcd34af..5ea7a6e 100644
--- a/arch/x86/cpu/qemu/fw_cfg.c
+++ b/arch/x86/cpu/qemu/fw_cfg.c
@@ -10,7 +10,10 @@
 #include <malloc.h>
 #include <asm/io.h>
 #include <asm/fw_cfg.h>
+#include <asm/tables.h>
+#include <asm/e820.h>
 #include <linux/list.h>
+#include <memalign.h>
 
 static bool fwcfg_present;
 static bool fwcfg_dma_present;
@@ -204,6 +207,256 @@ err:
 	return -ENOMEM;
 }
 
+#ifdef CONFIG_QEMU_ACPI_TABLE
+static struct fw_file *qemu_fwcfg_find_file(const char *name)
+{
+	struct list_head *entry;
+	struct fw_file *file;
+
+	list_for_each(entry, &fw_list) {
+		file = list_entry(entry, struct fw_file, list);
+		if (!strcmp(file->cfg.name, name))
+			return file;
+	}
+
+	return NULL;
+}
+
+/*
+ * This function allocates memory for ACPI tables
+ *
+ * @entry : BIOS linker command entry which tells where to allocate memory
+ *          (either high memory or low memory)
+ * @addr  : The address that should be used for low memory allcation. If the
+ *          memory allocation request is 'ZONE_HIGH' then this parameter will
+ *          be ignored.
+ * @return: 0 on success, or negative value on failure
+ */
+static int bios_linker_allocate(struct bios_linker_entry *entry,
+			   unsigned long *addr)
+{
+	uint32_t size, align;
+	struct fw_file *file;
+	unsigned long aligned_addr;
+
+	align = le32_to_cpu(entry->alloc.align);
+	/* align must be power of 2 */
+	if (align & (align - 1)) {
+		printf("error: wrong alignment %u\n", align);
+		return -EINVAL;
+	}
+
+	file = qemu_fwcfg_find_file(entry->alloc.file);
+	if (!file) {
+		printf("error: can't find file %s\n", entry->alloc.file);
+		return -ENOENT;
+	}
+
+	size = be32_to_cpu(file->cfg.size);
+
+	/*
+	 * ZONE_HIGH means we need to allocate from high memory, since
+	 * malloc space is already at the end of RAM, so we directly use it.
+	 * If allocation zone is ZONE_FSEG, then we use the 'addr' passed
+	 * in which is low memory
+	 */
+	if (entry->alloc.zone == BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH) {
+		aligned_addr = (unsigned long)memalign(align, size);
+		if (!aligned_addr) {
+			printf("error: allocating resource\n");
+			return -ENOMEM;
+		}
+	} else if (entry->alloc.zone == BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG) {
+		aligned_addr = ALIGN(*addr, align);
+	} else {
+		printf("error: invalid allocation zone\n");
+		return -EINVAL;
+	}
+
+	debug("bios_linker_allocate: allocate file %s, size %u, zone %d, align %u, addr 0x%lx\n",
+	      file->cfg.name, size, entry->alloc.zone, align, aligned_addr);
+
+	qemu_fwcfg_read_entry(be16_to_cpu(file->cfg.select),
+			      size, (void *)aligned_addr);
+	file->addr = aligned_addr;
+
+	/* adjust address for low memory allocation */
+	if (entry->alloc.zone == BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG)
+		*addr = (aligned_addr + size);
+
+	return 0;
+}
+
+/*
+ * This function patches ACPI tables previously loaded
+ * by bios_linker_allocate()
+ *
+ * @entry : BIOS linker command entry which tells how to patch
+ *          ACPI tables
+ * @return: 0 on success, or negative value on failure
+ */
+static int bios_linker_add_pointer(struct bios_linker_entry *entry)
+{
+	struct fw_file *dest, *src;
+	uint32_t offset = le32_to_cpu(entry->pointer.offset);
+	uint64_t pointer = 0;
+
+	dest = qemu_fwcfg_find_file(entry->pointer.dest_file);
+	if (!dest || !dest->addr)
+		return -ENOENT;
+	src = qemu_fwcfg_find_file(entry->pointer.src_file);
+	if (!src || !src->addr)
+		return -ENOENT;
+
+	debug("bios_linker_add_pointer: dest->addr 0x%lx, src->addr 0x%lx, offset 0x%x size %u, 0x%llx\n",
+	      dest->addr, src->addr, offset, entry->pointer.size, pointer);
+
+	memcpy(&pointer, (char *)dest->addr + offset, entry->pointer.size);
+	pointer	= le64_to_cpu(pointer);
+	pointer += (unsigned long)src->addr;
+	pointer	= cpu_to_le64(pointer);
+	memcpy((char *)dest->addr + offset, &pointer, entry->pointer.size);
+
+	return 0;
+}
+
+/*
+ * This function updates checksum fields of ACPI tables previously loaded
+ * by bios_linker_allocate()
+ *
+ * @entry : BIOS linker command entry which tells where to update ACPI table
+ *          checksums
+ * @return: 0 on success, or negative value on failure
+ */
+static int bios_linker_add_checksum(struct bios_linker_entry *entry)
+{
+	struct fw_file *file;
+	uint8_t *data, cksum = 0;
+	uint8_t *cksum_start;
+
+	file = qemu_fwcfg_find_file(entry->cksum.file);
+	if (!file || !file->addr)
+		return -ENOENT;
+
+	data = (uint8_t *)(file->addr + le32_to_cpu(entry->cksum.offset));
+	cksum_start = (uint8_t *)(file->addr + le32_to_cpu(entry->cksum.start));
+	cksum = table_compute_checksum(cksum_start,
+				       le32_to_cpu(entry->cksum.length));
+	*data = cksum;
+
+	return 0;
+}
+
+unsigned install_e820_map(unsigned max_entries, struct e820entry *entries)
+{
+	entries[0].addr = 0;
+	entries[0].size = ISA_START_ADDRESS;
+	entries[0].type = E820_RAM;
+
+	entries[1].addr = ISA_START_ADDRESS;
+	entries[1].size = ISA_END_ADDRESS - ISA_START_ADDRESS;
+	entries[1].type = E820_RESERVED;
+
+	/*
+	 * since we use memalign(malloc) to allocate high memory for
+	 * storing ACPI tables, we need to reserve them in e820 tables,
+	 * otherwise kernel will reclaim them and data will be corrupted
+	 */
+	entries[2].addr = ISA_END_ADDRESS;
+	entries[2].size = gd->relocaddr - TOTAL_MALLOC_LEN - ISA_END_ADDRESS;
+	entries[2].type = E820_RAM;
+
+	/* for simplicity, reserve entire malloc space */
+	entries[3].addr = gd->relocaddr - TOTAL_MALLOC_LEN;
+	entries[3].size = TOTAL_MALLOC_LEN;
+	entries[3].type = E820_RESERVED;
+
+	entries[4].addr = gd->relocaddr;
+	entries[4].size = gd->ram_size - gd->relocaddr;
+	entries[4].type = E820_RESERVED;
+
+	entries[5].addr = CONFIG_PCIE_ECAM_BASE;
+	entries[5].size = CONFIG_PCIE_ECAM_SIZE;
+	entries[5].type = E820_RESERVED;
+
+	return 6;
+}
+
+/* This function loads and patches ACPI tables provided by QEMU */
+unsigned long write_acpi_tables(unsigned long addr)
+{
+	int i, ret = 0;
+	struct fw_file *file;
+	struct bios_linker_entry *table_loader;
+	struct bios_linker_entry *entry;
+	uint32_t size;
+	struct list_head *list;
+
+	/* make sure fw_list is loaded */
+	ret = qemu_fwcfg_read_firmware_list();
+	if (ret) {
+		printf("error: can't read firmware file list\n");
+		return addr;
+	}
+
+	file = qemu_fwcfg_find_file("etc/table-loader");
+	if (!file) {
+		printf("error: can't find etc/table-loader\n");
+		return addr;
+	}
+
+	size = be32_to_cpu(file->cfg.size);
+	if ((size % sizeof(*entry)) != 0) {
+		printf("error: table-loader maybe corrupted\n");
+		return addr;
+	}
+
+	table_loader = malloc(size);
+	if (!table_loader) {
+		printf("error: no memory for table-loader\n");
+		return addr;
+	}
+
+	qemu_fwcfg_read_entry(be16_to_cpu(file->cfg.select),
+			      size, table_loader);
+
+	for (i = 0; i < (size / sizeof(*entry)); i++) {
+		entry = table_loader + i;
+		switch (le32_to_cpu(entry->command)) {
+		case BIOS_LINKER_LOADER_COMMAND_ALLOCATE:
+			ret = bios_linker_allocate(entry, &addr);
+			if (ret)
+				goto out;
+			break;
+		case BIOS_LINKER_LOADER_COMMAND_ADD_POINTER:
+			ret = bios_linker_add_pointer(entry);
+			if (ret)
+				goto out;
+			break;
+		case BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM:
+			ret = bios_linker_add_checksum(entry);
+			if (ret)
+				goto out;
+			break;
+		default:
+			break;
+		}
+	}
+
+out:
+	if (ret) {
+		list_for_each(list, &fw_list) {
+			file = list_entry(list, struct fw_file, list);
+			if (file->addr)
+				free((void *)file->addr);
+		}
+	}
+
+	free(table_loader);
+	return addr;
+}
+#endif
+
 static int qemu_fwcfg_list_firmware(void)
 {
 	int ret;
diff --git a/arch/x86/include/asm/fw_cfg.h b/arch/x86/include/asm/fw_cfg.h
index 2acf43e..e9450c6 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
  */
diff --git a/arch/x86/lib/acpi_table.c b/arch/x86/lib/acpi_table.c
index ab1db7e..2ec5ad2 100644
--- a/arch/x86/lib/acpi_table.c
+++ b/arch/x86/lib/acpi_table.c
@@ -331,6 +331,10 @@ static void acpi_create_ssdt_generator(acpi_header_t *ssdt,
 	ssdt->checksum = table_compute_checksum((void *)ssdt, ssdt->length);
 }
 
+/*
+ * QEMU's version of write_acpi_tables is defined in
+ * arch/x86/cpu/qemu/fw_cfg.c
+ */
 unsigned long write_acpi_tables(unsigned long start)
 {
 	unsigned long current;
-- 
1.9.1



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