Re: [PATCH v12 05/22] selftests/vm: generic function to handle shadow key register

[Dave Hansen]

On 02/21/2018 05:55 PM, Ram Pai wrote:
> +static inline u32 pkey_to_shift(int pkey)
> +{
> +	return pkey * PKEY_BITS_PER_PKEY;
> +}

pkey_bit_position(), perhaps?

> +static inline pkey_reg_t reset_bits(int pkey, pkey_reg_t bits)
> +{
> +	u32 shift = pkey_to_shift(pkey);
> +
> +	return ~(bits << shift);
> +}

I'd prefer clear_pkey_flags() or maybe clear_pkey_bits().  "reset" can
mean "reset to 0" or "reset to 1".

Also, why the u32 here?  Isn't an int more appropriate?

> +static inline pkey_reg_t left_shift_bits(int pkey, pkey_reg_t bits)
> +{
> +	u32 shift = pkey_to_shift(pkey);
> +
> +	return (bits << shift);
> +}
> +
> +static inline pkey_reg_t right_shift_bits(int pkey, pkey_reg_t bits)
> +{
> +	u32 shift = pkey_to_shift(pkey);
> +
> +	return (bits >> shift);
> +}

Some comments on these would be handy.  Basically that this takes a
per-key flags value and puts it at the right position so it can be
shoved in the register.