Re: [PATCH v2 17/29] arm_mpam: Extend reset logic to allow devices to be reset any time

Ben Horgan
2025-09-12T11:42:24Z

Hi James,

On 9/10/25 21:42, James Morse wrote:
> cpuhp callbacks aren't the only time the MSC configuration may need to
> be reset. Resctrl has an API call to reset a class.
> If an MPAM error interrupt arrives it indicates the driver has
> misprogrammed an MSC. The safest thing to do is reset all the MSCs
> and disable MPAM.
>
> Add a helper to reset RIS via their class. Call this from mpam_disable(),
> which can be scheduled from the error interrupt handler.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
> Changes since v1:
> * more complete use of _srcu helpers.
> * Use guard macro for srcu.
> * Dropped a might_sleep() - something else will bark.
> ---
> drivers/resctrl/mpam_devices.c | 56 ++++++++++++++++++++++++++++++++--
> 1 file changed, 54 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index e7faf453b5d7..a9d3c4b09976 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
> @@ -842,8 +842,6 @@ static int mpam_reset_ris(void *arg)
> u16 partid, partid_max;
> struct mpam_msc_ris *ris = arg;
>
> - mpam_assert_srcu_read_lock_held();
> -

Remove where it is introduced. There is already one in
mpam_reset_ris_partid() at that time.

> if (ris->in_reset_state)
> return 0;

Reviewed-by: Ben Horgan <ben.horgan@arm.com>

Thanks,

Ben