On Fri, 20 Jul 2018 11:09:27 +0200
Janosch Frank <frankja@xxxxxxxxxxxxx> wrote:
> On 20.07.2018 10:58, Martin Schwidefsky wrote:
> > On Fri, 20 Jul 2018 09:44:48 +0100
> > Janosch Frank <frankja@xxxxxxxxxxxxx> wrote:
> >
> >> Similarly to the pte skey handling, where we set the storage key to
> >> the default key for each newly mapped pte, we have to also do that for
> >> huge pmds.
> >>
> >> With the PG_arch_1 flag we keep track if the area has already been
> >> cleared of its skeys.
> >>
> >> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> >> ---
> >> arch/s390/mm/gmap.c | 2 ++
> >> arch/s390/mm/hugetlbpage.c | 24 ++++++++++++++++++++++++
> >> 2 files changed, 26 insertions(+)
> >>
> >> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> >> index 6194a8a62aa0..409bc8f9d5b6 100644
> >> --- a/arch/s390/mm/gmap.c
> >> +++ b/arch/s390/mm/gmap.c
> >> @@ -2554,6 +2554,7 @@ static int __s390_enable_skey_hugetlb(pte_t *pte, unsigned long addr,
> >> {
> >> pmd_t *pmd = (pmd_t *)pte;
> >> unsigned long start, end;
> >> + struct page *page = pmd_page(*pmd);
> >>
> >> /*
> >> * The write check makes sure we do not set a key on shared
> >> @@ -2568,6 +2569,7 @@ static int __s390_enable_skey_hugetlb(pte_t *pte, unsigned long addr,
> >> start = pmd_val(*pmd) & HPAGE_MASK;
> >> end = start + HPAGE_SIZE - 1;
> >> __storage_key_init_range(start, end);
> >> + set_bit(PG_arch_1, &page->flags);
> >> return 0;
> >> }
> >>
> >> diff --git a/arch/s390/mm/hugetlbpage.c b/arch/s390/mm/hugetlbpage.c
> >> index e804090f4470..b0246c705a19 100644
> >> --- a/arch/s390/mm/hugetlbpage.c
> >> +++ b/arch/s390/mm/hugetlbpage.c
> >> @@ -123,6 +123,29 @@ static inline pte_t __rste_to_pte(unsigned long rste)
> >> return pte;
> >> }
> >>
> >> +static void clear_huge_pte_skeys(struct mm_struct *mm, unsigned long rste)
> >> +{
> >> + struct page *page;
> >> + unsigned long size, paddr;
> >> +
> >> + if (!mm_uses_skeys(mm) ||
> >> + rste & _SEGMENT_ENTRY_INVALID)
> >> + return;
> >> +
> >> + if ((rste & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3) {
> >> + page = pud_page(__pud(rste));
> >> + size = PUD_SIZE;
> >> + paddr = rste & PUD_MASK;
> >> + } else {
> >> + page = pmd_page(__pmd(rste));
> >> + size = PMD_SIZE;
> >> + paddr = rste & PMD_MASK;
> >> + }
> >> +
> >> + if (!test_and_set_bit(PG_arch_1, &page->flags))
> >> + __storage_key_init_range(paddr, paddr + size - 1);
> >> +}
> >> +
> >> void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
> >> pte_t *ptep, pte_t pte)
> >> {
> >> @@ -137,6 +160,7 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
> >> rste |= _REGION_ENTRY_TYPE_R3 | _REGION3_ENTRY_LARGE;
> >> else
> >> rste |= _SEGMENT_ENTRY_LARGE;
> >> + clear_huge_pte_skeys(mm, rste);
> >> pte_val(*ptep) = rste;
> >> }
> >>
> >
> > That looks promising but I miss the hunk for arch_clear_hugepage_flags() to reset
> > the PG_arch_1 bit again when the huge page is freed.
> >
>
> Yes, missing this:
>
> diff --git i/arch/s390/include/asm/hugetlb.h
> w/arch/s390/include/asm/hugetlb.h
> index 9c5fc50204dd..2d1afa58a4b6 100644
> --- i/arch/s390/include/asm/hugetlb.h
> +++ w/arch/s390/include/asm/hugetlb.h
> @@ -37,7 +37,10 @@ static inline int prepare_hugepage_range(struct file
> *file,
> return 0;
> }
>
> -#define arch_clear_hugepage_flags(page) do { } while (0)
> +static inline void arch_clear_hugepage_flags(struct page *page)
> +{
> + clear_bit(PG_arch_1, &page->flags);
> +}
Jup, thats it.
Reviewed-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
