linux-kernel - Re: [PATCH] arch/x86: Fix boot_cpu

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Date:   Mon, 30 Jul 2018 13:53:50 -0400
From:   Prarit Bhargava <prarit@...hat.com>
To:     bp@...en8.de
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        sironi@...zon.de, tony.luck@...el.com, stable@...r.kernel.org
Subject: Re: [PATCH] arch/x86: Fix boot_cpu_data.microcode version output



On 07/30/2018 01:49 PM, Prarit Bhargava wrote:
> On systems where a runtime microcode update has occurred the microcode
> version output in a MCE log record is wrong because
> boot_cpu_data.microcode is not updated during runtime.
> 
> Update boot_cpu_data.microcode when the BSP's microcode is updated.
> 
> Fixes: fa94d0c6e0f3 ("x86/MCE: Save microcode revision in machine check records")
> Suggested-by: Borislav Petkov <bp@...en8.com>
> Signed-off-by: Prarit Bhargava <prarit@...hat.com>
> Cc: stable@...r.kernel.org
> Cc: sironi@...zon.de
> Cc: tony.luck@...el.com
> ---
>  arch/x86/kernel/cpu/microcode/amd.c   | 4 ++++
>  arch/x86/kernel/cpu/microcode/intel.c | 4 ++++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
> index 0624957aa068..7f5b32535ac7 100644
> --- a/arch/x86/kernel/cpu/microcode/amd.c
> +++ b/arch/x86/kernel/cpu/microcode/amd.c
> @@ -537,6 +537,10 @@ static enum ucode_state apply_microcode_amd(int cpu)
>  	uci->cpu_sig.rev = mc_amd->hdr.patch_id;
>  	c->microcode = mc_amd->hdr.patch_id;
>  
> +	/* Update boot_cpu_data's revision too, if we're on the BSP: */
> +	if (c->cpu_index == boot_cpu_data.cpu_index)
> +		boot_cpu_data.microcode = rev;
> +

Borislav, hold off on this.  I want to double check something with AMD.

I think this has to be

	boot_cpu_data.microcode = mc_amd->hdr.patch_id;

I'm going to grab some old/new microcode and test.  I do know that the Intel
update below works.

P.

>  	return UCODE_UPDATED;
>  }
>  
> diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
> index 97ccf4c3b45b..256d336cbc04 100644
> --- a/arch/x86/kernel/cpu/microcode/intel.c
> +++ b/arch/x86/kernel/cpu/microcode/intel.c
> @@ -851,6 +851,10 @@ static enum ucode_state apply_microcode_intel(int cpu)
>  	uci->cpu_sig.rev = rev;
>  	c->microcode = rev;
>  
> +	/* Update boot_cpu_data's revision too, if we're on the BSP: */
> +	if (c->cpu_index == boot_cpu_data.cpu_index)
> +		boot_cpu_data.microcode = rev;
> +
>  	return UCODE_UPDATED;
>  }
>  
>