linux-kernel - Re: [PATCH 1/9] x86, pkeys: do not special case protection key 0

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Message-ID: <e63d1ea6-4a1e-063c-6cc0-ad80fb554515@intel.com>
Date:   Mon, 26 Mar 2018 10:39:09 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Ram Pai <linuxram@...ibm.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        tglx@...utronix.de, mpe@...erman.id.au, mingo@...nel.org,
        akpm@...ux-foundation.org, shuah@...nel.org
Subject: Re: [PATCH 1/9] x86, pkeys: do not special case protection key 0

On 03/26/2018 10:35 AM, Ram Pai wrote:
>>  #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
>>  	if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
>> -		/* pkey 0 is the default and always allocated */
>> +		/* pkey 0 is the default and allocated implicitly */
>>  		mm->context.pkey_allocation_map = 0x1;
> In the second patch, you introduce DEFAULT_KEY. Maybe you 
> should introduce here and express the above code as
> 
> 		mm->context.pkey_allocation_map = (0x1 << DEFAULT_KEY);
> 
> Incase your default key changes to something else, you are still good.

That's a good cleanup, but I'd rather limit _this_ set to bug fixes.