[RFC PATCH 6/6] ARM: mm: Transparent huge page support for non-LPAE systems.
Christoffer Dall
c.dall at virtualopensystems.com
Tue Jan 8 13:17:30 EST 2013
On Tue, Jan 8, 2013 at 12:59 PM, Steve Capper <steve.capper at arm.com> wrote:
> On Fri, Jan 04, 2013 at 05:04:57AM +0000, Christoffer Dall wrote:
>> On Thu, Oct 18, 2012 at 12:15 PM, Steve Capper <steve.capper at arm.com> wrote:
>> > Much of the required code for THP has been implemented in the earlier non-LPAE
>> > HugeTLB patch.
>> >
>> > One more domain bits is used (to store whether or not the THP is splitting).
>>
>> s/bits/bit/
>>
> Thanks.
>
>> >
>> > Some THP helper functions are defined; and we have to re-define pmd_page such
>> > that it distinguishes between page tables and sections.
>>
>> super nit: not sure the semi-colon is warranted here.
>>
> Cheers, it is a superfluous semicolon.
>
>> >
>> > Signed-off-by: Will Deacon <will.deacon at arm.com>
>> > Signed-off-by: Steve Capper <steve.capper at arm.com>
>> > ---
>> > arch/arm/Kconfig | 2 +-
>> > arch/arm/include/asm/pgtable-2level.h | 68 ++++++++++++++++++++++++++++++++-
>> > arch/arm/include/asm/pgtable-3level.h | 2 +
>> > arch/arm/include/asm/pgtable.h | 7 +++-
>> > 4 files changed, 75 insertions(+), 4 deletions(-)
>> >
>> > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
>> > index 9621d5f..d459673 100644
>> > --- a/arch/arm/Kconfig
>> > +++ b/arch/arm/Kconfig
>> > @@ -1773,7 +1773,7 @@ config SYS_SUPPORTS_HUGETLBFS
>> >
>> > config HAVE_ARCH_TRANSPARENT_HUGEPAGE
>> > def_bool y
>> > - depends on ARM_LPAE
>> > + depends on SYS_SUPPORTS_HUGETLBFS
>> >
>> > source "mm/Kconfig"
>> >
>> > diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
>> > index 34f4775..67eabb4 100644
>> > --- a/arch/arm/include/asm/pgtable-2level.h
>> > +++ b/arch/arm/include/asm/pgtable-2level.h
>> > @@ -179,6 +179,13 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
>> > clean_pmd_entry(pmdp); \
>> > } while (0)
>> >
>> > +
>>
>> stray whitespace?
>>
>
> Thanks.
>
>> > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>> > +#define _PMD_HUGE(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_SECT)
>> > +#else
>> > +#define _PMD_HUGE(pmd) (0)
>> > +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>> > +
>> > /* we don't need complex calculations here as the pmd is folded into the pgd */
>> > #define pmd_addr_end(addr,end) (end)
>> >
>> > @@ -197,7 +204,6 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
>> >
>> > #define HPAGE_SHIFT PMD_SHIFT
>> > #define HPAGE_SIZE (_AC(1, UL) << HPAGE_SHIFT)
>> > -#define HPAGE_MASK (~(HPAGE_SIZE - 1))
>> > #define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
>> >
>> > #define HUGE_LINUX_PTE_COUNT (PAGE_OFFSET >> HPAGE_SHIFT)
>> > @@ -209,6 +215,7 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
>> > */
>> > #define PMD_DSECT_DIRTY (_AT(pmdval_t, 1) << 5)
>> > #define PMD_DSECT_AF (_AT(pmdval_t, 1) << 6)
>> > +#define PMD_DSECT_SPLITTING (_AT(pmdval_t, 1) << 7)
>> >
>> > #define PMD_BIT_FUNC(fn,op) \
>> > static inline pmd_t pmd_##fn(pmd_t pmd) { pmd_val(pmd) op; return pmd; }
>> > @@ -261,8 +268,67 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
>> > return __pmd(pmdval);
>> > }
>> >
>> > +#else
>> > +#define HPAGE_SIZE 0
>>
>> why this and the conditional define of _PMD_HUGE, you could just do
>> like in pgtable.h and put the #ifdef around the condition in
>> pmd_page(pmt_t pmd).
>>
>
> Thanks, I'll take a look at this.
>
>> > #endif /* CONFIG_SYS_SUPPORTS_HUGETLBFS */
>> >
>> > +#define HPAGE_MASK (~(HPAGE_SIZE - 1))
>> > +
>> > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>> > +#define pmd_mkhuge(pmd) (__pmd((pmd_val(pmd) & ~PMD_TYPE_MASK) | PMD_TYPE_SECT))
>> > +
>> > +PMD_BIT_FUNC(mkold, &= ~PMD_DSECT_AF);
>> > +PMD_BIT_FUNC(mksplitting, |= PMD_DSECT_SPLITTING);
>> > +PMD_BIT_FUNC(mkdirty, |= PMD_DSECT_DIRTY);
>> > +PMD_BIT_FUNC(mkyoung, |= PMD_DSECT_AF);
>> > +PMD_BIT_FUNC(mkwrite, |= PMD_SECT_AP_WRITE);
>> > +PMD_BIT_FUNC(mknotpresent, &= ~PMD_TYPE_MASK);
>> > +
>> > +#define pmd_trans_splitting(pmd) (pmd_val(pmd) & PMD_DSECT_SPLITTING)
>> > +#define pmd_young(pmd) (pmd_val(pmd) & PMD_DSECT_AF)
>> > +#define pmd_write(pmd) (pmd_val(pmd) & PMD_SECT_AP_WRITE)
>> > +#define pmd_trans_huge(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_SECT)
>> > +
>> > +static inline unsigned long pmd_pfn(pmd_t pmd)
>> > +{
>> > + /*
>> > + * for a section, we need to mask off more of the pmd
>> > + * before looking up the pfn
>> > + */
>> > + if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_SECT)
>> > + return __phys_to_pfn(pmd_val(pmd) & HPAGE_MASK);
>> > + else
>> > + return __phys_to_pfn(pmd_val(pmd) & PHYS_MASK);
>> > +}
>> > +
>> > +static inline pmd_t pfn_pmd(unsigned long pfn, pgprot_t prot)
>> > +{
>> > + pmd_t pmd = __pmd(__pfn_to_phys(pfn) | PMD_SECT_AP_READ | PMD_SECT_nG);
>> > +
>> > + return pmd_modify(pmd, prot);
>> > +}
>> > +
>> > +#define mk_pmd(page,prot) pfn_pmd(page_to_pfn(page),prot);
>> > +
>> > +static inline int has_transparent_hugepage(void)
>> > +{
>> > + return 1;
>> > +}
>> > +
>> > +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>> > +
>> > +static inline struct page *pmd_page(pmd_t pmd)
>> > +{
>> > + /*
>> > + * for a section, we need to mask off more of the pmd
>> > + * before looking up the page as it is a section descriptor.
>> > + */
>> > + if (_PMD_HUGE(pmd))
>> > + return phys_to_page(pmd_val(pmd) & HPAGE_MASK);
>> > +
>> > + return phys_to_page(pmd_val(pmd) & PHYS_MASK);
>> > +}
>> > +
>> > #endif /* __ASSEMBLY__ */
>> >
>> > #endif /* _ASM_PGTABLE_2LEVEL_H */
>> > diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h
>> > index 31c071f..8360814 100644
>> > --- a/arch/arm/include/asm/pgtable-3level.h
>> > +++ b/arch/arm/include/asm/pgtable-3level.h
>> > @@ -197,6 +197,8 @@ PMD_BIT_FUNC(mknotpresent, &= ~PMD_TYPE_MASK);
>> > #define pfn_pmd(pfn,prot) (__pmd(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
>> > #define mk_pmd(page,prot) pfn_pmd(page_to_pfn(page),prot)
>> >
>> > +#define pmd_page(pmd) pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
>> > +
>> > static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
>> > {
>> > const pmdval_t mask = PMD_SECT_USER | PMD_SECT_XN | PMD_SECT_RDONLY;
>> > diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
>> > index 767aa7c..2d96381 100644
>> > --- a/arch/arm/include/asm/pgtable.h
>> > +++ b/arch/arm/include/asm/pgtable.h
>> > @@ -169,11 +169,14 @@ extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
>> >
>> > static inline pte_t *pmd_page_vaddr(pmd_t pmd)
>> > {
>> > +#ifdef SYS_SUPPORTS_HUGETLBFS
>> > + if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_SECT)
>> > + return __va(pmd_val(pmd) & HPAGE_MASK);
>> > +#endif
>> > +
>> > return __va(pmd_val(pmd) & PHYS_MASK & (s32)PAGE_MASK);
>> > }
>> >
>> > -#define pmd_page(pmd) pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
>> > -
>> > #ifndef CONFIG_HIGHPTE
>> > #define __pte_map(pmd) pmd_page_vaddr(*(pmd))
>> > #define __pte_unmap(pte) do { } while (0)
>> > --
>> > 1.7.9.5
>> >
>> The whole series looks functionally correct to me:
>>
>> Reviewed-by: Christoffer Dall <c.dall at virtualopensystems.com>
>>
>
> A big thank you for going through this Christoffer.
>
> I'm correcting/simplifying/testing the huge pages code and will send out another
> version soon.
>
Great. This really makes a performance difference for running VMs, so
I'm happy to have the code for KVM/ARM. Please remember to cc me
and/or the kvmarm mailing list for a new version of this series.
-Christoffer
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