linux-kernel - Re: [PATCH v4 08/13] x86/power/keylocker: Restore internal wrapping key from the ACPI S3/4 sleep states

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Date:   Wed, 22 Dec 2021 04:58:40 +0000
From:   "Bae, Chang Seok" <chang.seok.bae@...el.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
CC:     Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...e.de>,
        "Dave Hansen" <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...nel.org>,
        "Lutomirski, Andy" <luto@...nel.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        Eric Biggers <ebiggers@...nel.org>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        "Gairuboyina, Charishma1" <charishma1.gairuboyina@...el.com>,
        "Dwarakanath, Kumar N" <kumar.n.dwarakanath@...el.com>,
        "Krishnakumar, Lalithambika" <lalithambika.krishnakumar@...el.com>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v4 08/13] x86/power/keylocker: Restore internal wrapping
 key from the ACPI S3/4 sleep states

On Dec 17, 2021, at 07:42, Rafael J. Wysocki <rafael@...nel.org> wrote:
> 
> First, I would change the subject to "x86/PM/keylocker: Restore
> internal wrapping key on resume from ACPI S3/S4".
> 
> On Tue, Dec 14, 2021 at 2:00 AM Chang S. Bae <chang.seok.bae@...el.com> wrote:
>> 
>> When the system state switches to these sleep states, the internal
>> wrapping key gets reset in the CPU state.
> 
> And here I would say
> 
> "When the system enters the ACPI S3 or S4 sleep state, the internal
> wrapping key is discarded.”
> 

<snip>

>> /**
>>  * setup_keylocker - Enable the feature.
>>  * @c:         A pointer to struct cpuinfo_x86
>> @@ -49,6 +87,7 @@ void __ref setup_keylocker(struct cpuinfo_x86 *c)
>> 
>>        if (c == &boot_cpu_data) {
>>                u32 eax, ebx, ecx, edx;
>> +               bool backup_available;
>> 
>>                cpuid_count(KEYLOCKER_CPUID, 0, &eax, &ebx, &ecx, &edx);
>>                /*
>> @@ -62,10 +101,49 @@ void __ref setup_keylocker(struct cpuinfo_x86 *c)
>>                        goto disable;
>>                }
>> 
>> +               backup_available = (ebx & KEYLOCKER_CPUID_EBX_BACKUP) ? true : false;
> 
> Why not
> 
> backup_available = !!(ebx & KEYLOCKER_CPUID_EBX_BACKUP);
> 
> Apart from this it looks OK, so with the above addressed, please feel
> free to add
> 
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> to this patch.

Thanks Rafael! Will do.

Chang