src/cpu/microcode: Add code to update microcode in assembly

Add code to update microcode from cbfsfiles using assembly.

Change-Id: I8bd192f3f345651db0010239f99293ae63b00652
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/27091
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

1 files changed, 162 insertions, 0 deletions

diff --git a/src/cpu/intel/microcode/microcode_asm.S b/src/cpu/intel/microcode/microcode_asm.S
new file mode 100644
index 0000000000..ef85760269
--- /dev/null
+++ b/src/cpu/intel/microcode/microcode_asm.S
@@ -0,0 +1,162 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2018 Arthur Heymans <arthur@aheymans.xyz>
+ *
+ * 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.
+ */
+
+/*
+ * input %esp: return address (not pointer to return address!)
+ * clobber the content of eax, ebx, ecx, edx, esi, edi, and ebp
+ */
+
+#include <cpu/x86/post_code.h>
+#include <cpu/x86/msr.h>
+#include <arch/x86/walkcbfs.S>
+
+#define HEADER_VER_OFFSET 0
+#define UPDATE_VER_OFFSET 4
+#define DATE_OFFSET 8
+#define PROCESSOR_SIG_OFFSET 12
+#define CHKSUM_OFFSET 16
+#define LOADER_REV_OFFSET 20
+#define PROCESSOR_FLAG 24
+#define DATA_SIZE_OFFSET 28
+#define TOTAL_OFFSET 32
+#define HEADER_SIZE 48
+
+/*
+ * The microcode header is 48 bytes wide and has the following
+ * structure:
+ *   Header Version      : 32bit
+ *   Update Revision     : 32bit
+ *   Date                : 32bit
+ *   Processor Signature : 32bit
+ *   Checksum            : 32bit
+ *   Loader Revision     : 32bit
+ *   Processor Flags     : 32bit
+ *   Data Size           : 32bit
+ *   Total Size          : 32bit
+ *   Reserved            : 96bit
+ *
+ * We only check if the Processor signature and flags match and check
+ * if the revision of the update is newer than what is installed
+ */
+
+.section .text
+.global update_bsp_microcode
+
+update_bsp_microcode:
+	/* Keep return address */
+	movl	%esp, %edx
+	/* find microcodes in cbfs */
+	leal	microcode_name, %esi
+	movl	$1f, %esp
+	jmp	walkcbfs_asm
+
+1:
+	/* restore return address */
+	movl	%edx, %esp
+
+	cmpl	$0, %eax
+	je	end_microcode_update
+	movl	CBFS_FILE_OFFSET(%eax), %ebx
+	bswap	%ebx
+	addl	%eax, %ebx
+	movl	%ebx, %esi
+
+	movl	CBFS_FILE_LEN(%eax), %edi
+	bswap	%edi
+	addl	%esi, %edi
+
+	/*
+	 * Microcode revision -> %ebx
+	 * Processor flags -> %ebp
+	 * Current installed microcode revision -> %edx
+	 */
+
+	/* Processor family+model signature=cpuid_eax(1) */
+	movl	$1, %eax
+	cpuid
+	movl	%eax, %ebx
+
+	/* Processor flags
+	 * rdmsr 0x17
+	 * pf = 1 << ((msr.hi >> 18) & 7) */
+	movl	$IA32_PLATFORM_ID, %ecx
+	rdmsr
+	shr	$18, %edx
+	andl	$7, %edx
+	movl	$1, %eax
+	/* needs to be %cl for shl */
+	movl	%edx, %ecx
+	shl	%cl, %eax
+	movl	%eax, %ebp
+
+	/* Fetch the current microcode revision*/
+	xorl	%eax, %eax
+	xorl	%edx, %edx
+	movl	$IA32_BIOS_SIGN_ID, %ecx
+	wrmsr
+	movl	$0x1, %eax
+	cpuid
+	movl	$IA32_BIOS_SIGN_ID, %ecx
+	rdmsr
+
+check_microcode_entry:
+	/* Test if header revision is non zero */
+	cmpl	$0, HEADER_VER_OFFSET(%esi)
+	je	end_microcode_update
+
+	/* Processor family+model signature=cpuid_eax(1) */
+	cmpl	PROCESSOR_SIG_OFFSET(%esi), %ebx
+	jne	next_entry
+
+	/* Processor flags */
+	cmpl	PROCESSOR_FLAG(%esi), %ebp
+	jne	next_entry
+
+	/* Check if revision is higher than current */
+	cmpl	UPDATE_VER_OFFSET(%esi), %edx
+	/* Don't upgrade if already greater or equal */
+	jge	end_microcode_update
+
+	/* Do actual update */
+	movl	%esi, %eax
+	addl	$HEADER_SIZE, %eax
+	xorl	%edx, %edx
+	movl	$IA32_BIOS_UPDT_TRIG, %ecx
+	wrmsr
+
+	jmp	end_microcode_update
+
+next_entry:
+	movl	TOTAL_OFFSET(%esi), %eax
+	cmpl	$0, %eax
+	jne	1f
+	/* Newer microcode updates include a size field, whereas older
+	 * containers set it at 0 and are exactly 2048 bytes long */
+	addl	$2048, %esi
+	jmp	check_end
+1:
+	addl	%eax, %esi
+
+check_end:
+	cmpl	%esi, %edi
+	ja	check_microcode_entry
+
+end_microcode_update:
+	jmp	*%esp
+
+microcode_name:
+	.string	"cpu_microcode_blob.bin"
+
+_update_bsp_microcode_end: