On Tue, May 23, 2017 at 2:05 PM, Oliver O'Halloran <oohall@xxxxxxxxx> wrote:
> Add support for the devmap bit on PTEs and PMDs for PPC64 Book3S. This
> is used to differentiate device backed memory from transparent huge
> pages since they are handled in more or less the same manner by the core
> mm code.
>
> Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Oliver O'Halloran <oohall@xxxxxxxxx>
> ---
> v1 -> v2: Properly differentiate THP and PMD Devmap entries. The
> mm core assumes that pmd_trans_huge() and pmd_devmap() are mutually
> exclusive and v1 had pmd_trans_huge() being true on a devmap pmd.
>
> Aneesh, this has been fleshed out substantially since v1. Can you
> re-review it? Also no explicit gup support is required in this patch
> since devmap support was added generic GUP as a part of making x86 use
> the generic version.
> ---
> arch/powerpc/include/asm/book3s/64/hash-64k.h | 2 +-
> arch/powerpc/include/asm/book3s/64/pgtable.h | 37 ++++++++++++++++++++++++++-
> arch/powerpc/include/asm/book3s/64/radix.h | 2 +-
> arch/powerpc/mm/hugetlbpage.c | 2 +-
> arch/powerpc/mm/pgtable-book3s64.c | 4 +--
> arch/powerpc/mm/pgtable-hash64.c | 4 ++-
> arch/powerpc/mm/pgtable-radix.c | 3 ++-
> arch/powerpc/mm/pgtable_64.c | 2 +-
> 8 files changed, 47 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/hash-64k.h b/arch/powerpc/include/asm/book3s/64/hash-64k.h
> index 9732837aaae8..eaaf613c5347 100644
> --- a/arch/powerpc/include/asm/book3s/64/hash-64k.h
> +++ b/arch/powerpc/include/asm/book3s/64/hash-64k.h
> @@ -180,7 +180,7 @@ static inline void mark_hpte_slot_valid(unsigned char *hpte_slot_array,
> */
> static inline int hash__pmd_trans_huge(pmd_t pmd)
> {
> - return !!((pmd_val(pmd) & (_PAGE_PTE | H_PAGE_THP_HUGE)) ==
> + return !!((pmd_val(pmd) & (_PAGE_PTE | H_PAGE_THP_HUGE | _PAGE_DEVMAP)) ==
> (_PAGE_PTE | H_PAGE_THP_HUGE));
> }
Like Aneesh suggested, I think we can probably skip this check here
>
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 85bc9875c3be..24634e92dd0b 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -79,6 +79,9 @@
>
> #define _PAGE_SOFT_DIRTY _RPAGE_SW3 /* software: software dirty tracking */
> #define _PAGE_SPECIAL _RPAGE_SW2 /* software: special page */
> +#define _PAGE_DEVMAP _RPAGE_SW1
> +#define __HAVE_ARCH_PTE_DEVMAP
> +
> /*
> * Drivers request for cache inhibited pte mapping using _PAGE_NO_CACHE
> * Instead of fixing all of them, add an alternate define which
> @@ -599,6 +602,16 @@ static inline pte_t pte_mkhuge(pte_t pte)
> return pte;
> }
>
> +static inline pte_t pte_mkdevmap(pte_t pte)
> +{
> + return __pte(pte_val(pte) | _PAGE_SPECIAL|_PAGE_DEVMAP);
> +}
> +
> +static inline int pte_devmap(pte_t pte)
> +{
> + return !!(pte_raw(pte) & cpu_to_be64(_PAGE_DEVMAP));
> +}
> +
> static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
> {
> /* FIXME!! check whether this need to be a conditional */
> @@ -963,6 +976,9 @@ static inline pte_t *pmdp_ptep(pmd_t *pmd)
> #define pmd_mk_savedwrite(pmd) pte_pmd(pte_mk_savedwrite(pmd_pte(pmd)))
> #define pmd_clear_savedwrite(pmd) pte_pmd(pte_clear_savedwrite(pmd_pte(pmd)))
>
> +#define pud_pfn(...) (0)
> +#define pgd_pfn(...) (0)
> +
Don't get these bits.. why are they zero?
> #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
> #define pmd_soft_dirty(pmd) pte_soft_dirty(pmd_pte(pmd))
> #define pmd_mksoft_dirty(pmd) pte_pmd(pte_mksoft_dirty(pmd_pte(pmd)))
> @@ -1137,7 +1153,6 @@ static inline int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
> return true;
> }
>
> -
> #define arch_needs_pgtable_deposit arch_needs_pgtable_deposit
> static inline bool arch_needs_pgtable_deposit(void)
> {
> @@ -1146,6 +1161,26 @@ static inline bool arch_needs_pgtable_deposit(void)
> return true;
> }
>
> +static inline pmd_t pmd_mkdevmap(pmd_t pmd)
> +{
> + return pte_pmd(pte_mkdevmap(pmd_pte(pmd)));
> +}
> +
> +static inline int pmd_devmap(pmd_t pmd)
> +{
> + return pte_devmap(pmd_pte(pmd));
> +}
This should be defined only if #ifdef __HAVE_ARCH_PTE_DEVMAP
The rest looks OK
Balbir Singh.
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