The documentation for system vector length configuration does not cover all
cases where unsupported values are written, tighten it up.

Reported-by: Edmund Grimley-Evans <edmund.grimley-evans@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 Documentation/arch/arm64/sme.rst | 5 ++---
 Documentation/arch/arm64/sve.rst | 5 ++---
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/Documentation/arch/arm64/sme.rst b/Documentation/arch/arm64/sme.rst
index 3133d0e91b48..f4376c06f447 100644
--- a/Documentation/arch/arm64/sme.rst
+++ b/Documentation/arch/arm64/sme.rst
@@ -379,9 +379,8 @@ The regset data starts with struct user_za_header, containing:
 /proc/sys/abi/sme_default_vector_length
 
     Writing the text representation of an integer to this file sets the system
-    default vector length to the specified value, unless the value is greater
-    than the maximum vector length supported by the system in which case the
-    default vector length is set to that maximum.
+    default vector length to the specified value rounded to a supported value
+    using the same rules as for setting vector length via PR_SME_SET_VL.
 
     The result can be determined by reopening the file and reading its
     contents.
diff --git a/Documentation/arch/arm64/sve.rst b/Documentation/arch/arm64/sve.rst
index b45a2da19bf1..8d8837fc39ec 100644
--- a/Documentation/arch/arm64/sve.rst
+++ b/Documentation/arch/arm64/sve.rst
@@ -423,9 +423,8 @@ The regset data starts with struct user_sve_header, containing:
 /proc/sys/abi/sve_default_vector_length
 
     Writing the text representation of an integer to this file sets the system
-    default vector length to the specified value, unless the value is greater
-    than the maximum vector length supported by the system in which case the
-    default vector length is set to that maximum.
+    default vector length to the specified value rounded to a supported value
+    using the same rules as for setting vector length via PR_SVE_SET_VL.
 
     The result can be determined by reopening the file and reading its
     contents.

-- 
2.30.2

On Wed, Jan 24, 2024 at 06:12:37PM +0000, Mark Brown wrote:
> The documentation for system vector length configuration does not cover all
> cases where unsupported values are written, tighten it up.
> 
> Reported-by: Edmund Grimley-Evans <edmund.grimley-evans@arm.com>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>  Documentation/arch/arm64/sme.rst | 5 ++---
>  Documentation/arch/arm64/sve.rst | 5 ++---
>  2 files changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/arch/arm64/sme.rst b/Documentation/arch/arm64/sme.rst
> index 3133d0e91b48..f4376c06f447 100644
> --- a/Documentation/arch/arm64/sme.rst
> +++ b/Documentation/arch/arm64/sme.rst
> @@ -379,9 +379,8 @@ The regset data starts with struct user_za_header, containing:
>  /proc/sys/abi/sme_default_vector_length
>  
>      Writing the text representation of an integer to this file sets the system
> -    default vector length to the specified value, unless the value is greater
> -    than the maximum vector length supported by the system in which case the
> -    default vector length is set to that maximum.
> +    default vector length to the specified value rounded to a supported value
> +    using the same rules as for setting vector length via PR_SME_SET_VL.
>  
>      The result can be determined by reopening the file and reading its
>      contents.
> diff --git a/Documentation/arch/arm64/sve.rst b/Documentation/arch/arm64/sve.rst
> index b45a2da19bf1..8d8837fc39ec 100644
> --- a/Documentation/arch/arm64/sve.rst
> +++ b/Documentation/arch/arm64/sve.rst
> @@ -423,9 +423,8 @@ The regset data starts with struct user_sve_header, containing:
>  /proc/sys/abi/sve_default_vector_length
>  
>      Writing the text representation of an integer to this file sets the system
> -    default vector length to the specified value, unless the value is greater
> -    than the maximum vector length supported by the system in which case the
> -    default vector length is set to that maximum.
> +    default vector length to the specified value rounded to a supported value
> +    using the same rules as for setting vector length via PR_SVE_SET_VL.
>  
>      The result can be determined by reopening the file and reading its
>      contents.

Since you picked up my suggestion, I guess I owe you a

Reviewed-by: Dave Martin <Dave.Martin@arm.com>

Cheers
---Dave