linux-kernel - Re: [PATCH v2 2/7] selftests/mm: Add support to test 4PB VA on PPC64

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <5FA05361-1FA8-4CAA-AF23-7BB0974DA78B@nvidia.com>
Date: Thu, 03 Jul 2025 10:41:39 -0400
From: Zi Yan <ziy@...dia.com>
To: Aboorva Devarajan <aboorvad@...ux.ibm.com>
Cc: akpm@...ux-foundation.org, Liam.Howlett@...cle.com,
 lorenzo.stoakes@...cle.com, shuah@...nel.org, pfalcato@...e.de,
 david@...hat.com, baolin.wang@...ux.alibaba.com, npache@...hat.com,
 ryan.roberts@....com, dev.jain@....com, baohua@...nel.org,
 linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org, donettom@...ux.ibm.com, ritesh.list@...il.com
Subject: Re: [PATCH v2 2/7] selftests/mm: Add support to test 4PB VA on PPC64

On 3 Jul 2025, at 2:06, Aboorva Devarajan wrote:

> From: Donet Tom <donettom@...ux.ibm.com>
>
> PowerPC64 supports a 4PB virtual address space, but this test was
> previously limited to 512TB. This patch extends the coverage up to
> the full 4PB VA range on PowerPC64.
>
> Memory from 0 to 128TB is allocated without an address hint, while
> allocations from 128TB to 4PB use a hint address.
>
> Signed-off-by: Donet Tom <donettom@...ux.ibm.com>
> Signed-off-by: Aboorva Devarajan <aboorvad@...ux.ibm.com>
> ---
>  tools/testing/selftests/mm/virtual_address_range.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/tools/testing/selftests/mm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c
> index e24c36a39f22..619acf0b9239 100644
> --- a/tools/testing/selftests/mm/virtual_address_range.c
> +++ b/tools/testing/selftests/mm/virtual_address_range.c
> @@ -50,6 +50,7 @@
>  #define NR_CHUNKS_256TB   (NR_CHUNKS_128TB * 2UL)
>  #define NR_CHUNKS_384TB   (NR_CHUNKS_128TB * 3UL)
>  #define NR_CHUNKS_3840TB  (NR_CHUNKS_128TB * 30UL)
> +#define NR_CHUNKS_3968TB  (NR_CHUNKS_128TB * 31UL)
>
>  #define ADDR_MARK_128TB  (1UL << 47) /* First address beyond 128TB */
>  #define ADDR_MARK_256TB  (1UL << 48) /* First address beyond 256TB */
> @@ -59,6 +60,11 @@
>  #define HIGH_ADDR_SHIFT 49
>  #define NR_CHUNKS_LOW   NR_CHUNKS_256TB
>  #define NR_CHUNKS_HIGH  NR_CHUNKS_3840TB
> +#elif defined(__PPC64__)
> +#define HIGH_ADDR_MARK  ADDR_MARK_128TB
> +#define HIGH_ADDR_SHIFT 48
> +#define NR_CHUNKS_LOW   NR_CHUNKS_128TB
> +#define NR_CHUNKS_HIGH  NR_CHUNKS_3968TB
>  #else
>  #define HIGH_ADDR_MARK  ADDR_MARK_128TB
>  #define HIGH_ADDR_SHIFT 48

Could you also update the comment above this code to say PowerPC64 also
supports 4PB virtual address space?

>From the comment, arm64 supports 4PB but its NR_CHUNKS_HIGH is only 3840TB,
whereas PowerPC64 here can get to 3968TB. I do not know why arm64’s
4PB is smaller. ;)

Otherwise, the patch looks good to me.

Reviewed-by: Zi Yan <ziy@...dia.com>

Best Regards,
Yan, Zi