[patch 3/5] x86/microcode/amd: Cache builtin/initrd microcode early

From: Thomas Gleixner
Date: Tue Oct 10 2023 - 11:09:05 EST


There is no reason to scan builtin/initrd microcode on each AP.

Cache the builtin/initrd microcode in an early initcall so that the early
AP loader can utilize the cache.

The existing fs initcall which invoked save_microcode_in_initrd_amd() is
still required to maintain the initrd_gone flag. Rename it accordingly.
This will be removed once the AP loader code is converted to use the cache.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/microcode/amd.c | 8 +++++++-
arch/x86/kernel/cpu/microcode/core.c | 20 ++++----------------
2 files changed, 11 insertions(+), 17 deletions(-)

--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -527,12 +527,17 @@ void load_ucode_amd_early(unsigned int c

static enum ucode_state load_microcode_amd(u8 family, const u8 *data, size_t size);

-int __init save_microcode_in_initrd_amd(unsigned int cpuid_1_eax)
+static int __init save_microcode_in_initrd(void)
{
+ unsigned int cpuid_1_eax = native_cpuid_eax(1);
+ struct cpuinfo_x86 *c = &boot_cpu_data;
struct cont_desc desc = { 0 };
enum ucode_state ret;
struct cpio_data cp;

+ if (c->x86_vendor != X86_VENDOR_AMD || c->x86 < 0x10)
+ return 0;
+
find_blobs_in_containers(cpuid_1_eax, &cp);
if (!(cp.data && cp.size))
return -EINVAL;
@@ -549,6 +554,7 @@ int __init save_microcode_in_initrd_amd(

return 0;
}
+early_initcall(save_microcode_in_initrd);

/*
* a small, trivial cache of per-family ucode patches
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -185,24 +185,13 @@ void load_ucode_ap(void)
}
}

-static int __init save_microcode_in_initrd(void)
+/* Temporary workaround until find_microcode_in_initrd() is __init */
+static int __init mark_initrd_gone(void)
{
- struct cpuinfo_x86 *c = &boot_cpu_data;
- int ret = -EINVAL;
-
- switch (c->x86_vendor) {
- case X86_VENDOR_AMD:
- if (c->x86 >= 0x10)
- ret = save_microcode_in_initrd_amd(cpuid_eax(1));
- break;
- default:
- break;
- }
-
initrd_gone = true;
-
- return ret;
+ return 0;
}
+fs_initcall(mark_initrd_gone);

struct cpio_data find_microcode_in_initrd(const char *path)
{
@@ -895,5 +884,4 @@ static int __init microcode_init(void)
return error;

}
-fs_initcall(save_microcode_in_initrd);
late_initcall(microcode_init);