[PATCH 20/33] arm_mpam: Extend reset logic to allow devices to be reset any time
From: Ben Horgan <ben.horgan@arm.com>
Date: 2025-11-07 12:37:13
Also in:
linux-acpi, lkml
Subsystem:
mpam driver, the rest · Maintainers:
James Morse, Ben Horgan, Linus Torvalds
From: James Morse <james.morse@arm.com> 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> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Reviewed-by: Ben Horgan <ben.horgan@arm.com> Tested-by: Fenghua Yu <fenghuay@nvidia.com> Tested-by: Shaopeng Tan <redacted> Tested-by: Peter Newman <redacted> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- drivers/resctrl/mpam_devices.c | 57 ++++++++++++++++++++++++++++++++-- 1 file changed, 54 insertions(+), 3 deletions(-)
diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index bcdf4fbc3941..a8efd3e02c62 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c@@ -809,15 +809,13 @@ static void mpam_reset_ris_partid(struct mpam_msc_ris *ris, u16 partid) /* * Called via smp_call_on_cpu() to prevent migration, while still being - * pre-emptible. + * pre-emptible. Caller must hold mpam_srcu. */ static int mpam_reset_ris(void *arg) { u16 partid, partid_max; struct mpam_msc_ris *ris = arg; - WARN_ON_ONCE(!srcu_read_lock_held((&mpam_srcu))); - if (ris->in_reset_state) return 0;
@@ -1341,8 +1339,55 @@ static void mpam_enable_once(void) mpam_partid_max + 1, mpam_pmg_max + 1); } +static void mpam_reset_component_locked(struct mpam_component *comp) +{ + struct mpam_vmsc *vmsc; + + lockdep_assert_cpus_held(); + + guard(srcu)(&mpam_srcu); + list_for_each_entry_srcu(vmsc, &comp->vmsc, comp_list, + srcu_read_lock_held(&mpam_srcu)) { + struct mpam_msc *msc = vmsc->msc; + struct mpam_msc_ris *ris; + + list_for_each_entry_srcu(ris, &vmsc->ris, vmsc_list, + srcu_read_lock_held(&mpam_srcu)) { + if (!ris->in_reset_state) + mpam_touch_msc(msc, mpam_reset_ris, ris); + ris->in_reset_state = true; + } + } +} + +static void mpam_reset_class_locked(struct mpam_class *class) +{ + struct mpam_component *comp; + + lockdep_assert_cpus_held(); + + guard(srcu)(&mpam_srcu); + list_for_each_entry_srcu(comp, &class->components, class_list, + srcu_read_lock_held(&mpam_srcu)) + mpam_reset_component_locked(comp); +} + +static void mpam_reset_class(struct mpam_class *class) +{ + cpus_read_lock(); + mpam_reset_class_locked(class); + cpus_read_unlock(); +} + +/* + * Called in response to an error IRQ. + * All of MPAMs errors indicate a software bug, restore any modified + * controls to their reset values. + */ void mpam_disable(struct work_struct *ignored) { + int idx; + struct mpam_class *class; struct mpam_msc *msc, *tmp; mutex_lock(&mpam_cpuhp_state_lock);
@@ -1352,6 +1397,12 @@ void mpam_disable(struct work_struct *ignored) } mutex_unlock(&mpam_cpuhp_state_lock); + idx = srcu_read_lock(&mpam_srcu); + list_for_each_entry_srcu(class, &mpam_classes, classes_list, + srcu_read_lock_held(&mpam_srcu)) + mpam_reset_class(class); + srcu_read_unlock(&mpam_srcu, idx); + mutex_lock(&mpam_list_lock); list_for_each_entry_safe(msc, tmp, &mpam_all_msc, all_msc_list) mpam_msc_destroy(msc);
--
2.43.0