linux-kernel - Re: [PATCH 2/3] x86/microcode: Fix the ancient deprecated microcode loading method

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Date:   Fri, 5 Apr 2019 23:55:26 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Borislav Petkov <bp@...en8.de>
cc:     LKML <linux-kernel@...r.kernel.org>, Jann Horn <jannh@...gle.com>,
        X86 ML <x86@...nel.org>
Subject: Re: [PATCH 2/3] x86/microcode: Fix the ancient deprecated microcode
 loading method

On Fri, 5 Apr 2019, Borislav Petkov wrote:

> From: Borislav Petkov <bp@...e.de>
> 
> The commit in Fixes: added the new define UCODE_NEW to denote that an

That reads odd. What's wrong with:

Commit 2613f36ed965 added ....

or

A recent commit added

mm?

> update should happen only when newer microcode (than installed on the
> system) has been found.
> 
> But it missed adjusting that for the old /dev/cpu/microcode loading
> interface. Fix it.
> 
> Fixes: 2613f36ed965 ("x86/microcode: Attempt late loading only when new microcode is present")
> Signed-off-by: Borislav Petkov <bp@...e.de>
> Cc: Jann Horn <jannh@...gle.com>

Other than that:

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>

> ---
>  arch/x86/kernel/cpu/microcode/core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
> index 5260185cbf7b..8a4a7823451a 100644
> --- a/arch/x86/kernel/cpu/microcode/core.c
> +++ b/arch/x86/kernel/cpu/microcode/core.c
> @@ -418,8 +418,9 @@ static int do_microcode_update(const void __user *buf, size_t size)
>  		if (ustate == UCODE_ERROR) {
>  			error = -1;
>  			break;
> -		} else if (ustate == UCODE_OK)
> +		} else if (ustate == UCODE_NEW) {
>  			apply_microcode_on_target(cpu);
> +		}
>  	}
>  
>  	return error;
> -- 
> 2.21.0
> 
>