microcode_intel.c
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/*
* Copyright (c) 2014 Google, Inc
* Copyright (C) 2000 Ronald G. Minnich
*
* Microcode update for Intel PIII and later CPUs
*
* SPDX-License-Identifier: GPL-2.0
*/
#include <common.h>
#include <errno.h>
#include <fdtdec.h>
#include <libfdt.h>
#include <asm/cpu.h>
#include <asm/msr.h>
#include <asm/msr-index.h>
#include <asm/processor.h>
#include <asm/arch/microcode.h>
/**
* struct microcode_update - standard microcode header from Intel
*
* We read this information out of the device tree and use it to determine
* whether the update is applicable or not. We also use the same structure
* to read information from the CPU.
*/
struct microcode_update {
uint header_version;
uint update_revision;
uint date_code;
uint processor_signature;
uint checksum;
uint loader_revision;
uint processor_flags;
const void *data;
int size;
};
static int microcode_decode_node(const void *blob, int node,
struct microcode_update *update)
{
update->data = fdt_getprop(blob, node, "data", &update->size);
if (!update->data)
return -EINVAL;
update->data += UCODE_HEADER_LEN;
update->size -= UCODE_HEADER_LEN;
update->header_version = fdtdec_get_int(blob, node,
"intel,header-version", 0);
update->update_revision = fdtdec_get_int(blob, node,
"intel,update-revision", 0);
update->date_code = fdtdec_get_int(blob, node,
"intel,date-code", 0);
update->processor_signature = fdtdec_get_int(blob, node,
"intel,processor-signature", 0);
update->checksum = fdtdec_get_int(blob, node, "intel,checksum", 0);
update->loader_revision = fdtdec_get_int(blob, node,
"intel,loader-revision", 0);
update->processor_flags = fdtdec_get_int(blob, node,
"intel,processor-flags", 0);
return 0;
}
static inline uint32_t microcode_read_rev(void)
{
/*
* Some Intel CPUs can be very finicky about the CPUID sequence used.
* So this is implemented in assembly so that it works reliably.
*/
uint32_t low, high;
asm volatile (
"xorl %%eax, %%eax\n"
"xorl %%edx, %%edx\n"
"movl %2, %%ecx\n"
"wrmsr\n"
"movl $0x01, %%eax\n"
"cpuid\n"
"movl %2, %%ecx\n"
"rdmsr\n"
: /* outputs */
"=a" (low), "=d" (high)
: /* inputs */
"i" (MSR_IA32_UCODE_REV)
: /* clobbers */
"ebx", "ecx"
);
return high;
}
static void microcode_read_cpu(struct microcode_update *cpu)
{
/* CPUID sets MSR 0x8B iff a microcode update has been loaded. */
unsigned int x86_model, x86_family;
struct cpuid_result result;
uint32_t low, high;
wrmsr(MSR_IA32_UCODE_REV, 0, 0);
result = cpuid(1);
rdmsr(MSR_IA32_UCODE_REV, low, cpu->update_revision);
x86_model = (result.eax >> 4) & 0x0f;
x86_family = (result.eax >> 8) & 0x0f;
cpu->processor_signature = result.eax;
cpu->processor_flags = 0;
if ((x86_model >= 5) || (x86_family > 6)) {
rdmsr(0x17, low, high);
cpu->processor_flags = 1 << ((high >> 18) & 7);
}
debug("microcode: sig=%#x pf=%#x revision=%#x\n",
cpu->processor_signature, cpu->processor_flags,
cpu->update_revision);
}
/* Get a microcode update from the device tree and apply it */
int microcode_update_intel(void)
{
struct microcode_update cpu, update;
const void *blob = gd->fdt_blob;
int skipped;
int count;
int node;
int ret;
int rev;
microcode_read_cpu(&cpu);
node = 0;
count = 0;
skipped = 0;
do {
node = fdtdec_next_compatible(blob, node,
COMPAT_INTEL_MICROCODE);
if (node < 0) {
debug("%s: Found %d updates\n", __func__, count);
return count ? 0 : skipped ? -EEXIST : -ENOENT;
}
ret = microcode_decode_node(blob, node, &update);
if (ret) {
debug("%s: Unable to decode update: %d\n", __func__,
ret);
return ret;
}
if (!(update.processor_signature == cpu.processor_signature &&
(update.processor_flags & cpu.processor_flags))) {
debug("%s: Skipping non-matching update, sig=%x, pf=%x\n",
__func__, update.processor_signature,
update.processor_flags);
skipped++;
continue;
}
wrmsr(MSR_IA32_UCODE_WRITE, (ulong)update.data, 0);
rev = microcode_read_rev();
debug("microcode: updated to revision 0x%x date=%04x-%02x-%02x\n",
rev, update.date_code & 0xffff,
(update.date_code >> 24) & 0xff,
(update.date_code >> 16) & 0xff);
if (update.update_revision != rev) {
printf("Microcode update failed\n");
return -EFAULT;
}
count++;
} while (1);
}