[PATCH next] arm_mpam: Fix MBA alloc_capable handling

[Zeng Heng]

The resctrl_arch_set_cdp_enabled() is never invoked with RDT_RESOURCE_MBA
as the rid parameter. Consequently,
mpam_resctrl_controls[RDT_RESOURCE_MBA].cdp_enabled always remains false,
making it unreliable for conditional checks.

The original logic uses this field to determine MBA state, causing a bug
where MBA allocation is permanently disabled after the mount with CDP
option. Remounting without CDP cannot restore the MBA partition capability.

Fix by using the cdp_enabled global parameter directly. Enable MBA
partition only when CDP is disabled and the MBA resource class is
present. Disable MBA partition otherwise.

Fixes: 6789fb99282c ("arm_mpam: resctrl: Add CDP emulation")
Signed-off-by: Zeng Heng <zengheng4@xxxxxxxxxx>
---
 drivers/resctrl/mpam_resctrl.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index a9938006d0e6..161fb8905e28 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -217,12 +217,10 @@ int resctrl_arch_set_cdp_enabled(enum resctrl_res_level rid, bool enable)
 		l3->mon.num_rmid = resctrl_arch_system_num_rmid_idx();
 
 	/* The mbw_max feature can't hide cdp as it's a per-partid maximum. */
-	if (cdp_enabled && !mpam_resctrl_controls[RDT_RESOURCE_MBA].cdp_enabled)
-		mpam_resctrl_controls[RDT_RESOURCE_MBA].resctrl_res.alloc_capable = false;
-
-	if (mpam_resctrl_controls[RDT_RESOURCE_MBA].cdp_enabled &&
-	    mpam_resctrl_controls[RDT_RESOURCE_MBA].class)
+	if (!cdp_enabled && mpam_resctrl_controls[RDT_RESOURCE_MBA].class)
 		mpam_resctrl_controls[RDT_RESOURCE_MBA].resctrl_res.alloc_capable = true;
+	else
+		mpam_resctrl_controls[RDT_RESOURCE_MBA].resctrl_res.alloc_capable = false;
 
 	if (enable) {
 		if (mpam_partid_max < 1)
-- 
2.25.1