linux-kernel - Re: [PATCH 7/7] x86/microcode: Recheck IBRS features on microcode reload

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Date:   Thu, 4 Jan 2018 11:10:44 -0800
From:   Tim Chen <tim.c.chen@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.de>,
        Andrea Arcangeli <aarcange@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/7] x86/microcode: Recheck IBRS features on microcode
 reload

On 01/04/2018 10:50 AM, Borislav Petkov wrote:
> On Thu, Jan 04, 2018 at 07:34:30PM +0100, Andrea Arcangeli wrote:
>> void spec_ctrl_rescan_cpuid(void)
>> {
>> 	int cpu;
>>
>> 	if (use_ibp_disable)
>> 		return;
>> 	mutex_lock(&spec_ctrl_mutex);
>> 	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL ||
>> 	    boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
>> 		/* detect spec ctrl related cpuid additions */
>> 		init_scattered_cpuid_features(&boot_cpu_data);
> 
> You don't need to noodle through all the scattered features - just the
> two bits.
> 

Sure.  Will update in rev 2.

Tim