On 09.02.2018 10:34, Janosch Frank wrote:
> When changing guest pmds, we don't need to take care of the
> corresponding host pmd. This means, we don't need to flush the host
> TLB entries and we don't need to notify on all gmaps.
>
> Let's introduce a function, that exchanges a pmd and takes care of the
> necessary flushing and notification.
stale comment, notification is handled in a different patch.
>
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx>
> ---
> arch/s390/mm/gmap.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index 4471cb9..16c877a9 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -23,6 +23,9 @@
>
> #define GMAP_SHADOW_FAKE_TABLE 1ULL
>
> +static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *old, pmd_t new,
> + unsigned long gaddr);
> +
> /**
> * gmap_alloc - allocate and initialize a guest address space
> * @mm: pointer to the parent mm_struct
> @@ -2174,6 +2177,31 @@ void ptep_notify(struct mm_struct *mm, unsigned long vmaddr,
> }
> EXPORT_SYMBOL_GPL(ptep_notify);
>
> +/**
> + * gmap_pmdp_xchg - exchange a gmap pmd with another and notify
dito, no notification yet
> + * @gmap: pointer to the guest address space structure
> + * @pmdp: pointer to the pmd entry
> + * @new: replacement entry
> + * @gaddr: the affected guest address
> + *
> + * This function is assumed to be called with the guest_table_lock
> + * held.
> + */
> +static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *pmdp, pmd_t new,
> + unsigned long gaddr)
> +{
> + if (MACHINE_HAS_TLB_GUEST)
> + __pmdp_idte(gaddr, (pmd_t *)pmdp,
> + IDTE_GUEST_ASCE, gmap->asce,
> + IDTE_GLOBAL);
This fits into two lines
> + if (MACHINE_HAS_IDTE)
> + __pmdp_idte(gaddr, (pmd_t *)pmdp,
> + 0, 0, IDTE_GLOBAL);
This fits into one line
> + else
> + __pmdp_csp(pmdp);
> + *pmdp = new;
> +}
> +
> static inline void thp_split_mm(struct mm_struct *mm)
> {
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>
Apart from that, looks good to me. (although very similar to
gmap_pmdp_idte_global - can we reuse gmap_pmdp_xchg() in
gmap_pmdp_idte_global?)
--
Thanks,
David / dhildenb
