Re: [Xen-devel] [V2 PATCH 5/9] x86/hvm: pkeys, add functions to get pkeys value from PTE

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 27.11.15 at 10:51, <huaitong.han@xxxxxxxxx> wrote:
> --- a/xen/include/asm-x86/x86_64/page.h
> +++ b/xen/include/asm-x86/x86_64/page.h
> @@ -134,6 +134,25 @@ typedef l4_pgentry_t root_pgentry_t;
>  #define get_pte_flags(x) (((int)((x) >> 40) & ~0xFFF) | ((int)(x) & 0xFFF))
>  #define put_pte_flags(x) (((intpte_t)((x) & ~0xFFF) << 40) | ((x) & 0xFFF))
>  
> +/*
> + * Protection keys define a new 4-bit protection key field
> + * (PKEY) in bits 62:59 of leaf entries of the page tables.
> + * This corresponds to bit 22:19 of a 24-bit flags.
> + *
> + * Notice: Bit 22 is used by _PAGE_GNTTAB which is visible to PV guests,
> + * so Protection keys must be disabled on PV guests.
> + */
> +#define _PAGE_PKEY_BIT0 (1u<<19)       /* Protection Keys, bit 1/4 */
> +#define _PAGE_PKEY_BIT1 (1u<<20)       /* Protection Keys, bit 2/4 */
> +#define _PAGE_PKEY_BIT2 (1u<<21)       /* Protection Keys, bit 3/4 */
> +#define _PAGE_PKEY_BIT3 (1u<<22)       /* Protection Keys, bit 4/4 */
> +
> +/* The order of mask _PAGE_PKEY_BIT0 is 19 */
> +#define get_pte_pkeys(x) ((int)(get_pte_flags(x) >> 19) & 0xF)

Pointless cast.

Jan


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