Thread (120 messages) 120 messages, 6 authors, 2026-01-13

Re: [PATCH v2 12/45] arm64: mpam: Add helpers to change a task or cpu's MPAM PARTID/PMG values

From: Jonathan Cameron <jonathan.cameron@huawei.com>
Date: 2026-01-05 17:21:47
Also in: kvmarm, lkml

On Fri, 19 Dec 2025 18:11:14 +0000
Ben Horgan [off-list ref] wrote:
From: James Morse <james.morse@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.

CC: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
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