Re: [PATCH] x86: Unbreak early processor microcode loading
From: Borislav Petkov
Date: Tue Mar 03 2015 - 11:39:52 EST
On Tue, Mar 03, 2015 at 11:10:44PM +0800, Daniel J Blueman wrote:
> The changes in 871b72dd "x86: microcode: use smp_call_function_single instead
> of set_cpus_allowed, cleanup of synchronization logic" introduced a check
> that prevents built-in microcode from being loaded before init starts.
>
> Conditionalise it on early microcode loading, so we get the expected behaviour
> when early microcode loading is enabled, and when it is not. This has potential
> importance as BIOSes often don't load the current microcode.
... probably because they don't have it. Which is also the main reason
for the existence of this microcode loader btw :)
>
> Signed-off-by: Daniel J Blueman <daniel@xxxxxxxxxxxxx>
> ---
> arch/x86/kernel/cpu/microcode/core.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
> index 36a8361..fa7f9fc 100644
> --- a/arch/x86/kernel/cpu/microcode/core.c
> +++ b/arch/x86/kernel/cpu/microcode/core.c
> @@ -391,9 +391,11 @@ static enum ucode_state microcode_init_cpu(int cpu, bool refresh_fw)
> if (collect_cpu_info(cpu))
> return UCODE_ERROR;
>
> +#if !defined(CONFIG_MICROCODE_AMD_EARLY) && !defined(CONFIG_MICROCODE_INTEL_EARLY)
> /* --dimm. Trigger a delayed update? */
> if (system_state != SYSTEM_RUNNING)
> return UCODE_NFOUND;
> +#endif
Ok, let me try to understand this correctly: where is this microcode
built in, into the kernel?
If yes, you should consider enabling the early loading
method and build in the microcode into the initrd, see
Documentation/x86/early-microcode.txt
This is the preferred method as we're applying the microcode much
earlier.
Back to you.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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