arm_mpam: Add helper to reset saved mbwu state

resctrl expects to reset the bandwidth counters when the filesystem
is mounted.

To allow this, add a helper that clears the saved mbwu state. Instead
of cross calling to each CPU that can access the component MSC to
write to the counter, set a flag that causes it to be zero'd on the
the next read. This is easily done by forcing a configuration update.

Signed-off-by: James Morse <james.morse@arm.com>
Cc: Peter Newman <peternewman@google.com>
Reviewed-by: Fenghua Yu <fenghuay@nvdia.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com>
Tested-by: Gavin Shan <gshan@redhat.com>
Tested-by: Zeng Heng <zengheng4@huawei.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index 693a315c4710..18d53c07b3d7 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -211,6 +211,7 @@ struct mon_cfg {
 /* Changes to msmon_mbwu_state are protected by the msc's mon_sel_lock. */
 struct msmon_mbwu_state {
 	bool		enabled;
+	bool		reset_on_next_read;
 	struct mon_cfg	cfg;
 
 	/*
@@ -370,6 +371,7 @@ int mpam_apply_config(struct mpam_component *comp, u16 partid,
 
 int mpam_msmon_read(struct mpam_component *comp, struct mon_cfg *ctx,
 		    enum mpam_device_features, u64 *val);
+void mpam_msmon_reset_mbwu(struct mpam_component *comp, struct mon_cfg *ctx);
 
 int mpam_get_cpumask_from_cache_id(unsigned long cache_id, u32 cache_level,
 				   cpumask_t *affinity);