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From:   Ben Gardon <bgardon@google.com>
Date:   Thu, 25 Feb 2021 15:42:46 -0800
Message-ID: <CANgfPd_UQ8p020=Rnkh4b_Atup9GAyUmYacpYP0-zBpWcsXm3Q@mail.gmail.com>
Subject: Re: [RFC PATCH v2 5/7] KVM: selftests: List all hugetlb src types
 specified with page sizes
To:     Yanan Wang <wangyanan55@huawei.com>
Cc:     kvm <kvm@vger.kernel.org>, linux-kselftest@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Jones <drjones@redhat.com>,
        Peter Xu <peterx@redhat.com>, Marc Zyngier <maz@kernel.org>,
        wanghaibin.wang@huawei.com, yuzenghui@huawei.com
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On Wed, Feb 24, 2021 at 10:03 PM Yanan Wang <wangyanan55@huawei.com> wrote:
>
> With VM_MEM_SRC_ANONYMOUS_HUGETLB, we currently can only use system
> default hugetlb pages to back the testing guest memory. In order to
> add flexibility, now list all the known hugetlb backing src types with
> different page sizes, so that we can specify use of hugetlb pages of the
> exact granularity that we want. And as all the known hugetlb page sizes
> are listed, it's appropriate for all architectures.
>
> Besides, the helper get_backing_src_pagesz() is added to get the
> granularity of different backing src types(anonumous, thp, hugetlb).
>
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> ---
>  .../testing/selftests/kvm/include/test_util.h | 19 ++++++-
>  tools/testing/selftests/kvm/lib/kvm_util.c    |  2 +-
>  tools/testing/selftests/kvm/lib/test_util.c   | 56 +++++++++++++++----
>  3 files changed, 63 insertions(+), 14 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
> index ef24c76ba89a..be5d08bcdca7 100644
> --- a/tools/testing/selftests/kvm/include/test_util.h
> +++ b/tools/testing/selftests/kvm/include/test_util.h
> @@ -70,16 +70,31 @@ struct timespec timespec_div(struct timespec ts, int divisor);
>  enum vm_mem_backing_src_type {
>         VM_MEM_SRC_ANONYMOUS,
>         VM_MEM_SRC_ANONYMOUS_THP,
> -       VM_MEM_SRC_ANONYMOUS_HUGETLB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_16KB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_64KB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_512KB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_1MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_2MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_8MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_16MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_32MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_256MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_512MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_1GB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_2GB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_16GB,
> +       NUM_SRC_TYPES,
>  };
>
>  struct vm_mem_backing_src_alias {
>         const char *name;
> -       enum vm_mem_backing_src_type type;
> +       uint32_t flag;
>  };
>
>  bool thp_configured(void);
>  size_t get_trans_hugepagesz(void);
> +const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i);
> +size_t get_backing_src_pagesz(uint32_t i);
>  void backing_src_help(void);
>  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
>
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index cc22c4ab7d67..b91c8e3a7ee1 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -757,7 +757,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
>         region->mmap_start = mmap(NULL, region->mmap_size,
>                                   PROT_READ | PROT_WRITE,
>                                   MAP_PRIVATE | MAP_ANONYMOUS
> -                                 | (src_type == VM_MEM_SRC_ANONYMOUS_HUGETLB ? MAP_HUGETLB : 0),
> +                                 | vm_mem_backing_src_alias(src_type)->flag,
>                                   -1, 0);
>         TEST_ASSERT(region->mmap_start != MAP_FAILED,
>                     "test_malloc failed, mmap_start: %p errno: %i",
> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> index f2d133f76c67..6780aa058f35 100644
> --- a/tools/testing/selftests/kvm/lib/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/test_util.c
> @@ -11,6 +11,7 @@
>  #include <stdlib.h>
>  #include <time.h>
>  #include <sys/stat.h>
> +#include <linux/mman.h>
>  #include "linux/kernel.h"
>
>  #include "test_util.h"
> @@ -112,12 +113,6 @@ void print_skip(const char *fmt, ...)
>         puts(", skipping test");
>  }
>
> -const struct vm_mem_backing_src_alias backing_src_aliases[] = {
> -       {"anonymous", VM_MEM_SRC_ANONYMOUS,},
> -       {"anonymous_thp", VM_MEM_SRC_ANONYMOUS_THP,},
> -       {"anonymous_hugetlb", VM_MEM_SRC_ANONYMOUS_HUGETLB,},
> -};
> -
>  bool thp_configured(void)
>  {
>         int ret;
> @@ -153,22 +148,61 @@ size_t get_trans_hugepagesz(void)
>         return size;
>  }
>
> +const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i)
> +{
> +       static const struct vm_mem_backing_src_alias aliases[] = {
> +               { "anonymous",               0                            },
> +               { "anonymous_thp",           0                            },
> +               { "anonymous_hugetlb_16kb",  MAP_HUGETLB | MAP_HUGE_16KB  },
> +               { "anonymous_hugetlb_64kb",  MAP_HUGETLB | MAP_HUGE_64KB  },
> +               { "anonymous_hugetlb_512kb", MAP_HUGETLB | MAP_HUGE_512KB },
> +               { "anonymous_hugetlb_1mb",   MAP_HUGETLB | MAP_HUGE_1MB   },
> +               { "anonymous_hugetlb_2mb",   MAP_HUGETLB | MAP_HUGE_2MB   },
> +               { "anonymous_hugetlb_8mb",   MAP_HUGETLB | MAP_HUGE_8MB   },
> +               { "anonymous_hugetlb_16mb",  MAP_HUGETLB | MAP_HUGE_16MB  },
> +               { "anonymous_hugetlb_32mb",  MAP_HUGETLB | MAP_HUGE_32MB  },
> +               { "anonymous_hugetlb_256mb", MAP_HUGETLB | MAP_HUGE_256MB },
> +               { "anonymous_hugetlb_512mb", MAP_HUGETLB | MAP_HUGE_512MB },
> +               { "anonymous_hugetlb_1gb",   MAP_HUGETLB | MAP_HUGE_1GB   },
> +               { "anonymous_hugetlb_2gb",   MAP_HUGETLB | MAP_HUGE_2GB   },
> +               { "anonymous_hugetlb_16gb",  MAP_HUGETLB | MAP_HUGE_16GB  },
> +       };
> +       _Static_assert(ARRAY_SIZE(aliases) == NUM_SRC_TYPES,
> +                      "Missing new backing src types?");
> +
> +       TEST_ASSERT(i < NUM_SRC_TYPES, "Backing src type ID %d too big", i);
> +
> +       return aliases + i;

NIT: This would be easier for me to read as return &aliases[i];


> +}
> +
> +size_t get_backing_src_pagesz(uint32_t i)
> +{
> +       uint32_t flag = vm_mem_backing_src_alias(i)->flag;
> +
> +       if (i == VM_MEM_SRC_ANONYMOUS)
> +               return getpagesize();
> +       if (i == VM_MEM_SRC_ANONYMOUS_THP)
> +               return get_trans_hugepagesz();
> +
> +       return 1ULL << (flag >> HUGETLB_FLAG_ENCODE_SHIFT);

It might also be nice to add a macro where MAP_HUGE_1GB and company
are defined to get the size for a given hugeTLB type. I think you're
mixing macros here too (which works because they're defined off one
another) but it's a little confusing.
MAP_HUGE_1GB and company are defined in
tools/include/uapi/linux/mman.h as equal to the values
HUGETLB_FLAG_ENCODE_1GB and friends in
tools/include/asm-generic/hugetlb_encode.h, but it seems like it would
be good to use MAP_HUGE_SHIFT to match in that case. I think this all
also relies on MAP_HUGETLB being in the bits less than MAP_HUGE_SHIFT
which isn't stated here. All up, I would add a macro to
tools/include/uapi/linux/mman.h:

#define MAP_HUGE_PAGE_SIZE(x) (1ULL << ((x >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK))

Or something similar, and use that here.

> +}
> +
>  void backing_src_help(void)
>  {
>         int i;
>
>         printf("Available backing src types:\n");
> -       for (i = 0; i < ARRAY_SIZE(backing_src_aliases); i++)
> -               printf("\t%s\n", backing_src_aliases[i].name);
> +       for (i = 0; i < NUM_SRC_TYPES; i++)
> +               printf("\t%s\n", vm_mem_backing_src_alias(i)->name);
>  }
>
>  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
>  {
>         int i;
>
> -       for (i = 0; i < ARRAY_SIZE(backing_src_aliases); i++)
> -               if (!strcmp(type_name, backing_src_aliases[i].name))
> -                       return backing_src_aliases[i].type;
> +       for (i = 0; i < NUM_SRC_TYPES; i++)
> +               if (!strcmp(type_name, vm_mem_backing_src_alias(i)->name))
> +                       return i;
>
>         backing_src_help();
>         TEST_FAIL("Unknown backing src type: %s", type_name);
> --
> 2.19.1
>