linux-kernel - Re: [patch V3 23/30] x86/microcode: Provide new control functions

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Message-ID: <87pm25feyr.ffs@tglx>
Date:   Tue, 26 Sep 2023 11:42:20 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Borislav Petkov <bp@...en8.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Nikolay Borisov <nik.borisov@...e.com>
Subject: Re: [patch V3 23/30] x86/microcode: Provide new control functions

On Sun, Sep 24 2023 at 08:58, Borislav Petkov wrote:
> On Tue, Sep 12, 2023 at 09:58:20AM +0200, Thomas Gleixner wrote:
>> +
>> +	ret = microcode_ops->apply_microcode(cpu);
>> +	this_cpu_write(ucode_ctrl.result, ret);
>> +	this_cpu_write(ucode_ctrl.ctrl, SCTRL_DONE);
>
> Do that update...
>
>> +
>> +	/*
>> +	 * If the update was successful, let the siblings run the apply()
>> +	 * callback. If not, tell them it's done. This also covers the
>> +	 * case where the CPU has uniform loading at package or system
>> +	 * scope implemented but does not advertise it.
>> +	 */
>> +	if (ret == UCODE_UPDATED || ret == UCODE_OK)
>> +		ctrl = SCTRL_APPLY;
>> +	else
>> +		ctrl = SCTRL_DONE;
>
> ... here, after having checked ret.

No. That's two different things. The write above stores the information
fir the current CPU, while this conditional constructs the command for
the siblings.