[PATCH v5 3/7] fs/resctrl: Clear the CDP state after the cleanup

[Jinjie Ruan]

From: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>

On MPAM a CLOSID is translated into the PARTIDs that the hardware
configuration uses. Without CDP, CLOSID c is PARTID c; with CDP it is
PARTIDs 2c and 2c+1. resctrl_unmount() clears the CDP state with
rdt_disable_ctx() before resctrl_fs_teardown() removes the groups, so
the teardown translates the CLOSIDs differently from when the groups
were set up.

For example, rdtgroup_unassign_cntrs() unassigns and resets the MBM
counters of each group through resctrl_arch_config_cntr(). On MPAM that
helper maps a counter to a monitor with the index
resctrl_get_config_index() returns for the CDP state. A counter assigned
while CDP was enabled is mapped to the monitor for PARTIDs 2c and 2c+1.
With CDP cleared, MPAM removes the mapping of PARTID c and resets the
monitor for PARTID c instead, so the mappings of PARTIDs 2c and 2c+1 are
left behind. The helper had an empty body on MPAM until the ABMC support
implemented it, which is when the teardown started to program the
mapping with the cleared state.

Clear the CDP state after resctrl_fs_teardown(), so the teardown runs
with the CDP state the configuration was created under.

x86 is not affected as its RMIDs and counters do not depend on the
CLOSID.

Fixes: 6e0e538a75ce ("arm_mpam: resctrl: Add resctrl_arch_config_cntr() for ABMC use")
Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 7.3+
---
 fs/resctrl/rdtgroup.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 5d0351453c2f..3312637fb514 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -3150,13 +3150,19 @@ static void resctrl_unmount(void)
 	cpus_read_lock();
 	mutex_lock(&rdtgroup_mutex);
 
-	rdt_disable_ctx();
-
 	/* Put everything back to default values. */
 	for_each_alloc_capable_rdt_resource(r)
 		resctrl_arch_reset_all_ctrls(r);
 
 	resctrl_fs_teardown();
+
+	/*
+	 * Clear the CDP state after the cleanup. The CDP state decides
+	 * which hardware configuration a CLOSID refers to, so the teardown
+	 * must run with the state the configuration was created under.
+	 */
+	rdt_disable_ctx();
+
 	if (resctrl_arch_alloc_capable())
 		resctrl_arch_disable_alloc();
 	if (resctrl_arch_mon_capable())
-- 
2.43.0