[PATCH v5 10/41] arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values

[Gavin Shan]

On 2/25/26 3:56 AM, Ben Horgan wrote:
> From: James Morse <james.morse at arm.com>
> 
> Care must be taken when modifying the PARTID and PMG of a task in any
> per-task structure as writing these values may race with the task being
> scheduled in, and reading the modified values.
> 
> Add helpers to set the task properties, and the CPU default value.  These
> use WRITE_ONCE() that pairs with the READ_ONCE() in mpam_get_regval() to
> avoid causing torn values.
> 
> Tested-by: Gavin Shan <gshan at redhat.com>
> Tested-by: Shaopeng Tan <tan.shaopeng at jp.fujitsu.com>
> Tested-by: Peter Newman <peternewman at google.com>
> Tested-by: Zeng Heng <zengheng4 at huawei.com>
> CC: Dave Martin <Dave.Martin at arm.com>
> Reviewed-by: Shaopeng Tan <tan.shaopeng at jp.fujitsu.com>
> Reviewed-by: Jonathan Cameron <jonathan.cameron at huawei.com>
> Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>
> Signed-off-by: James Morse <james.morse at arm.com>
> Signed-off-by: Ben Horgan <ben.horgan at arm.com>
> ---
> Changes since rfc:
> Keep comment attached to mpam_get_regval()
> Add internal helper, __mpam_regval() (Jonathan)
> 
> Changes since v3:
> Remove extra CONFIG_ARM64_MPAM guarding
> Extend CONFIG_ARM64_MPAM guarding
> ---
>   arch/arm64/include/asm/mpam.h | 28 +++++++++++++++++++++++++++-
>   1 file changed, 27 insertions(+), 1 deletion(-)
> 

Reviewed-by: Gavin Shan <gshan at redhat.com>