Re: [PATCH RFC V3 1/9] x86/pkeys: Create pkeys_common.h

[Ira Weiny]

On Tue, Oct 13, 2020 at 10:46:16AM -0700, Dave Hansen wrote:
> On 10/9/20 12:42 PM, ira.weiny@xxxxxxxxx wrote:
> > Protection Keys User (PKU) and Protection Keys Supervisor (PKS) work
> > in similar fashions and can share common defines.
> 
> Could we be a bit less abstract?  PKS and PKU each have:
> 1. A single control register
> 2. The same number of keys
> 3. The same number of bits in the register per key
> 4. Access and Write disable in the same bit locations
> 
> That means that we can share all the macros that synthesize and
> manipulate register values between the two features.

Sure.  Done.

> 
> > +++ b/arch/x86/include/asm/pkeys_common.h
> > @@ -0,0 +1,11 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef _ASM_X86_PKEYS_INTERNAL_H
> > +#define _ASM_X86_PKEYS_INTERNAL_H
> > +
> > +#define PKR_AD_BIT 0x1
> > +#define PKR_WD_BIT 0x2
> > +#define PKR_BITS_PER_PKEY 2
> > +
> > +#define PKR_AD_KEY(pkey)	(PKR_AD_BIT << ((pkey) * PKR_BITS_PER_PKEY))
> 
> Now that this has moved away from its use-site, it's a bit less
> self-documenting.  Let's add a comment:
> 
> /*
>  * Generate an Access-Disable mask for the given pkey.  Several of these
>  * can be OR'd together to generate pkey register values.
>  */

Fair enough. done.

> 
> Once that's in place, along with the updated changelog:
> 
> Reviewed-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

Thanks,
Ira