Re: [patch 04/26] Xen-paravirt_ops: Add pagetable accessors to pack and unpack pagetable entries

Ingo Molnar
2007-03-16T09:39:41Z

* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> Add a set of accessors to pack, unpack and modify page table entries
> (at all levels). This allows a paravirt implementation to control the
> contents of pgd/pmd/pte entries. For example, Xen uses this to
> convert the (pseudo-)physical address into a machine address when
> populating a pagetable entry, and converting back to pphys address
> when an entry is read.

looks good.

Acked-by: Ingo Molnar <mingo@elte.hu>

only some minor style nits:

> +static inline unsigned long long native_pgd_val(pgd_t pgd)
> +{
> + return pgd.pgd;
> +}
> +static inline unsigned long long native_pmd_val(pmd_t pmd)
> +{
> + return pmd.pmd;
> +}
> +static inline unsigned long long native_pte_val(pte_t pte)
> +{
> + return pte.pte_low | ((unsigned long long)pte.pte_high << 32);
> +}
> +static inline pgd_t native_make_pgd(unsigned long long val)
> +{
> + return (pgd_t) { val };
> +}
> +static inline pmd_t native_make_pmd(unsigned long long val)
> +{
> + return (pmd_t) { val };
> +}
> +static inline pte_t native_make_pte(unsigned long long val)
> +{
> + return (pte_t) { .pte_low = val, .pte_high = (val >> 32) } ;
> +}

missing newlines between inline functions.

> +#ifndef CONFIG_PARAVIRT
> +#define pmd_val(x) native_pmd_val(x)
> +#define __pmd(x) native_make_pmd(x)
> +#endif /* !CONFIG_PARAVIRT */

no need for the closing !CONFIG_PARAVIRT comment: this define is 2 lines
long so it's not that hard to find the start of the block. We typically
do the /* !CONFIG_XX */ comment only for larger blocks, and when
multiple #endif's intermix.

> +static inline unsigned long native_pgd_val(pgd_t pgd)
> +{
> + return pgd.pgd;
> +}
> +static inline unsigned long native_pte_val(pte_t pte)
> +{
> + return pte.pte_low;
> +}
> +static inline pgd_t native_make_pgd(unsigned long val)
> +{
> + return (pgd_t) { val };
> +}
> +static inline pte_t native_make_pte(unsigned long val)
> +{
> + return (pte_t) { .pte_low = val };
> +}

newlines.

> #define HPAGE_SHIFT 22
> #include <asm-generic/pgtable-nopmd.h>
> -#endif
> +#endif /* CONFIG_X86_PAE */

(for example here the #endif comment is justified.)

Ingo