"Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> writes:
> POWER9 supports hugepages of size 2M and 1G in radix MMU mode. This patch
> enables the usage of 1G page size for hugetlbfs. This also update the helper
> such we can do 1G page allocation at runtime.
>
> We still don't enable 1G page size on DD1 version. This is to avoid doing
> workaround mentioned in commit: 6d3a0379ebdc8 (powerpc/mm: Add
> radix__tlb_flush_pte_p9_dd1()
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> ---
> arch/powerpc/include/asm/book3s/64/hugetlb.h | 10 ++++++++++
> arch/powerpc/mm/hugetlbpage.c | 7 +++++--
> arch/powerpc/platforms/Kconfig.cputype | 1 +
> 3 files changed, 16 insertions(+), 2 deletions(-)
I think this patch is OK, but it's very confusing because it doesn't
mention that it's only talking about *generic* gigantic page support.
We have existing support for gigantic pages on powerpc, on several
platforms. This patch appears to break that, but I think doesn't in
practice?
So can you make it a bit clearer in the commit message, and the code,
that this is only about enabling the generic gigantic page support, and
is unrelated to the arch-specific gigantic page support.
cheers
> diff --git a/arch/powerpc/include/asm/book3s/64/hugetlb.h b/arch/powerpc/include/asm/book3s/64/hugetlb.h
> index 6666cd366596..5c28bd6f2ae1 100644
> --- a/arch/powerpc/include/asm/book3s/64/hugetlb.h
> +++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h
> @@ -50,4 +50,14 @@ static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
> else
> return entry;
> }
> +
> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
> +static inline bool gigantic_page_supported(void)
> +{
> + if (radix_enabled())
> + return true;
> + return false;
> +}
> +#endif
> +
> #endif
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index a4f33de4008e..80f6d2ed551a 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -763,8 +763,11 @@ static int __init add_huge_page_size(unsigned long long size)
> * Hash: 16M and 16G
> */
> if (radix_enabled()) {
> - if (mmu_psize != MMU_PAGE_2M)
> - return -EINVAL;
> + if (mmu_psize != MMU_PAGE_2M) {
> + if (cpu_has_feature(CPU_FTR_POWER9_DD1) ||
> + (mmu_psize != MMU_PAGE_1G))
> + return -EINVAL;
> + }
> } else {
> if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G)
> return -EINVAL;
> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
> index 684e886eaae4..b76ef6637016 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -344,6 +344,7 @@ config PPC_STD_MMU_64
> config PPC_RADIX_MMU
> bool "Radix MMU Support"
> depends on PPC_BOOK3S_64
> + select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
> default y
> help
> Enable support for the Power ISA 3.0 Radix style MMU. Currently this
> --
> 2.7.4
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