lkml.org 
[lkml]   [2023]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 39/46] hugetlb: x86: enable high-granularity mapping
On Thu, Jan 5, 2023 at 5:19 AM James Houghton <jthoughton@google.com> wrote:
>
> Now that HGM is fully supported for GENERAL_HUGETLB, x86 can enable it.
> The x86 KVM MMU already properly handles HugeTLB HGM pages (it does a
> page table walk to determine which size to use in the second-stage page
> table instead of, for example, checking vma_mmu_pagesize, like arm64
> does).
>
> We could also enable HugeTLB HGM for arm (32-bit) at this point, as it
> also uses GENERAL_HUGETLB and I don't see anything else that is needed
> for it. However, I haven't tested on arm at all, so I won't enable it.

Given that we are using a high bit for VM_HUGETLB_HGM, we can only
support 64-bit architectures. Userfaultfd minor faults is limited to
64-bit architectures for the same reason: VM_UFFD_MINOR uses a bit.

>
> Signed-off-by: James Houghton <jthoughton@google.com>
> ---
> arch/x86/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 3604074a878b..3d08cd45549c 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -126,6 +126,7 @@ config X86
> select ARCH_WANT_GENERAL_HUGETLB
> select ARCH_WANT_HUGE_PMD_SHARE
> select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if X86_64
> + select ARCH_WANT_HUGETLB_HIGH_GRANULARITY_MAPPING

This needs `if X86_64` at the end. Will be corrected for v2.

> select ARCH_WANT_LD_ORPHAN_WARN
> select ARCH_WANTS_THP_SWAP if X86_64
> select ARCH_HAS_PARANOID_L1D_FLUSH
> --
> 2.39.0.314.g84b9a713c41-goog
>

\
 
 \ /
  Last update: 2023-03-26 23:38    [W:0.625 / U:0.164 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site