[PATCH 19/27] arm_mpam: propagate MSC access errors for __ris_msmon_read()

[James Morse]

From: Andre Przywara <andre.przywara at arm.com>

Allow the function for RIS accesses to return an error, and propagate
read and write errors from the lower level up.
This function is a bit special, since it can be called via an SMP
helper, so the prototype must stay as void. So propagate any errors
using the "err" field in the struct passed in as the sole argument to
that function.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron at oss.qualcomm.com>
Reviewed-by: Ben Horgan <ben.horgan at arm.com>
Reviewed-by: Gavin Shan <gshan at redhat.com>
Tested-by: Gavin Shan <gshan at redhat.com> # on NVIDIA Grace Hopper
[morse: Fixed merge conflicts in mpam_save_mbwu_state() and __ris_msmon_read()]
Signed-off-by: James Morse <james.morse at arm.com>
---
 drivers/resctrl/mpam_devices.c | 37 +++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 72a5d1ab9684..853e5c5d7158 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -1339,6 +1339,10 @@ static u64 mpam_msmon_overflow_val(enum mpam_device_features type,
 	return overflow_val;
 }
 
+/*
+ * This function might be called via smp_call_function_any(), so propagate
+ * errors inside the arg struct.
+ */
 static void __ris_msmon_read_locked(struct mon_read *m)
 {
 	u64 now;
@@ -1357,7 +1361,9 @@ static void __ris_msmon_read_locked(struct mon_read *m)
 
 	mon_sel = FIELD_PREP(MSMON_CFG_MON_SEL_MON_SEL, ctx->mon) |
 		  FIELD_PREP(MSMON_CFG_MON_SEL_RIS, ris->ris_idx);
-	mpam_write_monsel_reg(msc, CFG_MON_SEL, mon_sel);
+	m->err = mpam_write_monsel_reg(msc, CFG_MON_SEL, mon_sel);
+	if (m->err)
+		return;
 
 	switch (m->type) {
 	case mpam_feat_msmon_mbwu_31counter:
@@ -1377,7 +1383,9 @@ static void __ris_msmon_read_locked(struct mon_read *m)
 	 * Read the existing configuration to avoid re-writing the same values.
 	 * This saves waiting for 'nrdy' on subsequent reads.
 	 */
-	read_msmon_ctl_flt_vals(m, &cur_ctl, &cur_flt);
+	m->err = read_msmon_ctl_flt_vals(m, &cur_ctl, &cur_flt);
+	if (m->err)
+		return;
 
 	if (mpam_feat_msmon_mbwu_31counter == m->type)
 		overflow = cur_ctl & MSMON_CFG_x_CTL_OFLOW_STATUS;
@@ -1391,18 +1399,24 @@ static void __ris_msmon_read_locked(struct mon_read *m)
 			  cur_ctl != (ctl_val | MSMON_CFG_x_CTL_EN);
 
 	if (config_mismatch || reset_on_next_read) {
-		write_msmon_ctl_flt_vals(m, ctl_val, flt_val);
+		m->err = write_msmon_ctl_flt_vals(m, ctl_val, flt_val);
+		if (m->err)
+			return;
 		overflow = false;
 	} else if (overflow) {
-		mpam_write_monsel_reg(msc, CFG_MBWU_CTL,
-				      cur_ctl &
-				      ~(MSMON_CFG_x_CTL_OFLOW_STATUS |
-					MSMON_CFG_MBWU_CTL_OFLOW_STATUS_L));
+		m->err = mpam_write_monsel_reg(msc, CFG_MBWU_CTL,
+					       cur_ctl &
+					       ~(MSMON_CFG_x_CTL_OFLOW_STATUS |
+					       MSMON_CFG_MBWU_CTL_OFLOW_STATUS_L));
+		if (m->err)
+			return;
 	}
 
 	switch (m->type) {
 	case mpam_feat_msmon_csu:
-		mpam_read_monsel_reg(msc, CSU, &now32);
+		m->err = mpam_read_monsel_reg(msc, CSU, &now32);
+		if (m->err)
+			return;
 		nrdy = now32 & MSMON___NRDY;
 		now = FIELD_GET(MSMON___VALUE, now32);
 
@@ -1424,7 +1438,9 @@ static void __ris_msmon_read_locked(struct mon_read *m)
 			else
 				now = FIELD_GET(MSMON___L_VALUE, now);
 		} else {
-			mpam_read_monsel_reg(msc, MBWU, &now32);
+			m->err = mpam_read_monsel_reg(msc, MBWU, &now32);
+			if (m->err)
+				return;
 			nrdy = now32 & MSMON___NRDY;
 			now = FIELD_GET(MSMON___VALUE, now32);
 		}
@@ -1831,6 +1847,9 @@ static int mpam_restore_mbwu_state(void *_ris)
 		__ris_msmon_read_locked(&mbwu_arg);
 
 		mpam_mon_sel_unlock(msc);
+
+		if (mbwu_arg.err && mbwu_arg.err != -EBUSY)
+			return mbwu_arg.err;
 	}
 
 	return 0;
-- 
2.53.0