Messages in this thread | | | Date | Wed, 04 Mar 2015 16:27:12 +0800 | From | Daniel J Blueman <> | Subject | Re: [PATCH] x86: Unbreak early processor microcode loading |
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On 04/03/2015 00:38, Borislav Petkov wrote: > 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@numascale.com> >> --- >> 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.
Yes, it's built into the kernel with config:
CONFIG_FIRMWARE_IN_KERNEL=y CONFIG_EXTRA_FIRMWARE="amd-ucode/microcode_amd.bin amd-ucode/microcode_amd_fam15h.bin" CONFIG_EXTRA_FIRMWARE_DIR="../firmware"
That's as some customer and in-house environments we use are initramfs-less and some we don't have direct control over the initramfs.
I don't see why built-in microcode loading shouldn't work, so I guess the question is, why was that 'system_state .. RUNNING' check introduced?
If just a cleanup and loading built-in microcode early was overlooked, it may be reasonable to conditionalise the check like so.
Thanks, Daniel
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