[PATCH v1 04/11] arm_mpam: Add missing mon_sel locking in MBWU restore

[Ben Horgan <ben.horgan@arm.com>]

The mon_sel_lock is used to protect the mbwu_state, as well as h/w accesses
that use MPAMCFG_MON_SEL. However, in mpam_restore_mbwu_state() mbwu_state
is accessed without holding the mon_sel_lock.

Add the missing locking.

Fixes: 41e8a14950e1 ("arm_mpam: Track bandwidth counter state for power management")
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
---
 drivers/resctrl/mpam_devices.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 11b10c3bc334..b34e2a368516 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -1648,16 +1648,24 @@ static int mpam_restore_mbwu_state(void *_ris)
 	u64 val;
 	struct mon_read mwbu_arg;
 	struct mpam_msc_ris *ris = _ris;
+	struct mpam_msc *msc = ris->vmsc->msc;
 	struct mpam_class *class = ris->vmsc->comp->class;
 
 	for (i = 0; i < ris->props.num_mbwu_mon; i++) {
+		if (WARN_ON_ONCE(!mpam_mon_sel_lock(msc)))
+			return -EIO;
+
 		if (ris->mbwu_state[i].enabled) {
 			mwbu_arg.ris = ris;
 			mwbu_arg.ctx = &ris->mbwu_state[i].cfg;
 			mwbu_arg.type = mpam_msmon_choose_counter(class);
 			mwbu_arg.val = &val;
 
+			mpam_mon_sel_unlock(msc);
+
 			__ris_msmon_read(&mwbu_arg);
+		} else {
+			mpam_mon_sel_unlock(msc);
 		}
 	}
 
-- 
2.43.0