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x86/microcode: Consolidate the loader enablement checking

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commit 5214a9f6c0 upstream.

Consolidate the whole logic which determines whether the microcode loader
should be enabled or not into a single function and call it everywhere.

Well, almost everywhere - not in mk_early_pgtbl_32() because there the kernel
is running without paging enabled and checking dis_ucode_ldr et al would
require physical addresses and uglification of the code.

But since this is 32-bit, the easier thing to do is to simply map the initrd
unconditionally especially since that mapping is getting removed later anyway
by zap_early_initrd_mapping() and avoid the uglification.

In doing so, address the issue of old 486er machines without CPUID
support, not booting current kernels.

  [ mingo: Fix no previous prototype for ‘microcode_loader_disabled’ [-Wmissing-prototypes] ]

Fixes: 4c585af718 ("x86/boot/32: Temporarily map initrd for microcode loading")
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/CANpbe9Wm3z8fy9HbgS8cuhoj0TREYEEkBipDuhgkWFvqX0UoVQ@mail.gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Borislav Petkov (AMD)
2025-04-14 11:59:33 +02:00
committed by Greg Kroah-Hartman
parent d63851049f
commit b76eaef983
6 changed files with 42 additions and 33 deletions
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2
arch/x86/kernel/cpu/microcode/intel.c
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@@ -395,7 +395,7 @@ static int __init save_builtin_microcode(void)
if (xchg(&ucode_patch_va, NULL) != UCODE_BSP_LOADED)
return 0;
if (dis_ucode_ldr || boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
if (microcode_loader_disabled() || boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
return 0;
uci.mc = get_microcode_blob(&uci, true);