[PATCH 21/33] arm_mpam: Extend reset logic to allow devices to be reset any time
From: James Morse <james.morse@arm.com>
Date: 2025-08-22 15:33:05
Also in:
linux-acpi, linux-devicetree, lkml
Subsystem:
mpam driver, the rest · Maintainers:
James Morse, Ben Horgan, Linus Torvalds
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> --- drivers/resctrl/mpam_devices.c | 62 +++++++++++++++++++++++++++++++-- drivers/resctrl/mpam_internal.h | 1 + 2 files changed, 61 insertions(+), 2 deletions(-)
diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 759244966736..3516cbe8623e 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c@@ -915,8 +915,6 @@ static int mpam_reset_ris(void *arg) u16 partid, partid_max; struct mpam_msc_ris *ris = arg; - mpam_assert_srcu_read_lock_held(); - if (ris->in_reset_state) return 0;
@@ -1569,6 +1567,66 @@ static void mpam_enable_once(void) mpam_partid_max + 1, mpam_pmg_max + 1); } +static void mpam_reset_component_locked(struct mpam_component *comp) +{ + int idx; + struct mpam_msc *msc; + struct mpam_vmsc *vmsc; + struct mpam_msc_ris *ris; + + might_sleep(); + lockdep_assert_cpus_held(); + + idx = srcu_read_lock(&mpam_srcu); + list_for_each_entry_rcu(vmsc, &comp->vmsc, comp_list) { + msc = vmsc->msc; + + list_for_each_entry_rcu(ris, &vmsc->ris, vmsc_list) { + if (!ris->in_reset_state) + mpam_touch_msc(msc, mpam_reset_ris, ris); + ris->in_reset_state = true; + } + } + srcu_read_unlock(&mpam_srcu, idx); +} + +static void mpam_reset_class_locked(struct mpam_class *class) +{ + int idx; + struct mpam_component *comp; + + lockdep_assert_cpus_held(); + + idx = srcu_read_lock(&mpam_srcu); + list_for_each_entry_rcu(comp, &class->components, class_list) + mpam_reset_component_locked(comp); + srcu_read_unlock(&mpam_srcu, idx); +} + +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(void) +{ + int idx; + struct mpam_class *class; + + 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); +} + /* * Enable mpam once all devices have been probed. * Scheduled by mpam_discovery_cpu_online() once all devices have been created.
diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index 466d670a01eb..b30fee2b7674 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h@@ -281,6 +281,7 @@ extern u8 mpam_pmg_max; /* Scheduled work callback to enable mpam once all MSC have been probed */ void mpam_enable(struct work_struct *work); +void mpam_disable(void); int mpam_get_cpumask_from_cache_id(unsigned long cache_id, u32 cache_level, cpumask_t *affinity);
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2.20.1