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

Re: [PATCH v2 09/45] arm64: mpam: Advertise the CPUs MPAM limits to the driver

From: Jonathan Cameron <jonathan.cameron@huawei.com>
Date: 2026-01-05 17:08:56
Also in: kvmarm, lkml

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

Requestors need to populate the MPAM fields for any traffic they send on
the interconnect. For the CPUs these values are taken from the
corresponding MPAMy_ELx register. Each requestor may have a limit on the
largest PARTID or PMG value that can be used. The MPAM driver has to
determine the system-wide minimum supported PARTID and PMG values.

To do this, the driver needs to be told what each requestor's limit is.

CPUs are special, but this infrastructure is also needed for the SMMU and
GIC ITS. Call the helper to tell the MPAM driver what the CPUs can do.

The return value can be ignored by the arch code as it runs well before the
MPAM driver starts probing.

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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