arm_mpam: Track bandwidth counter state for power management

Bandwidth counters need to run continuously to correctly reflect the
bandwidth.

Save the counter state when the hardware is reset due to CPU hotplug.
Add struct mbwu_state to track the bandwidth counter. Support for
tracking overflow with the same structure will be added in a
subsequent commit.

Cc: Zeng Heng <zengheng4@huawei.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Zeng Heng <zengheng4@huawei.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-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: James Morse <james.morse@arm.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index 12f0a5b7f39e..12ce80bc7ff7 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -91,7 +91,10 @@ struct mpam_msc {
 	 */
 	struct mutex		part_sel_lock;
 
-	/* cfg_lock protects the msc configuration. */
+	/*
+	 * cfg_lock protects the msc configuration and guards against mbwu_state
+	 * save and restore racing.
+	 */
 	struct mutex		cfg_lock;
 
 	/*
@@ -202,6 +205,19 @@ struct mon_cfg {
 	enum mon_filter_options opts;
 };
 
+/* Changes to msmon_mbwu_state are protected by the msc's mon_sel_lock. */
+struct msmon_mbwu_state {
+	bool		enabled;
+	struct mon_cfg	cfg;
+
+	/*
+	 * The value to add to the new reading to account for power management.
+	 */
+	u64		correction;
+
+	struct mpam_garbage	garbage;
+};
+
 struct mpam_class {
 	/* mpam_components in this class */
 	struct list_head	components;
@@ -295,6 +311,9 @@ struct mpam_msc_ris {
 	/* parent: */
 	struct mpam_vmsc	*vmsc;
 
+	/* msmon mbwu configuration is preserved over reset */
+	struct msmon_mbwu_state	*mbwu_state;
+
 	struct mpam_garbage	garbage;
 };