On 06/27/2018 03:55 PM, Janosch Frank wrote:
> From: Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx>
>
> 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.
>
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx>
> ---
> arch/s390/mm/gmap.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index bae0b4f674b5..f5b48426dde8 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
> @@ -2165,6 +2168,29 @@ void ptep_notify(struct mm_struct *mm, unsigned long vmaddr,
> }
> EXPORT_SYMBOL_GPL(ptep_notify);
>
> +/**
> + * gmap_pmdp_xchg - exchange a gmap pmd with another
> + * @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);
do we need an else here?
> + if (MACHINE_HAS_IDTE)
> + __pmdp_idte(gaddr, (pmd_t *)pmdp, 0, 0, IDTE_GLOBAL);
> + else
> + __pmdp_csp(pmdp);
> + *pmdp = new;
> +}
> +
> static inline void thp_split_mm(struct mm_struct *mm)
> {
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>
