MIPS: pm-cps: Use per-CPU variables as per-CPU, not per-core

The pm-cps code has up until now used per-CPU variables indexed by core,
rather than CPU number, in order to share data amongst sibling CPUs (ie.
VPs/threads in a core). This works fine for single cluster systems, but
with multi-cluster systems a core number is no longer unique in the
system, leading to sharing between CPUs that are not actually siblings.

Avoid this issue by using per-CPU variables as they are more generally
used - ie. access them using CPU numbers rather than core numbers.
Sharing between siblings is then accomplished by:
 - Assigning the same pointer to entries for each sibling CPU for the
   nc_asm_enter & ready_count variables, which allow this by virtue of
   being per-CPU pointers.

 - Indexing by the first CPU set in a CPUs cpu_sibling_map in the case
   of pm_barrier, for which we can't use the previous approach because
   the per-CPU variable is not a pointer.

Signed-off-by: Paul Burton <paulburton@kernel.org>
Signed-off-by: Dragan Mladjenovic <dragan.mladjenovic@syrmia.com>
Signed-off-by: Aleksandar Rikalo <arikalo@gmail.com>
Tested-by: Serge Semin <fancer.lancer@gmail.com>
Tested-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

diff --git a/arch/mips/kernel/pm-cps.c b/arch/mips/kernel/pm-cps.c
index d09ca77e624d76cdb15d4f65788ed7a47dfe8fc4..9369a8dc385e265849e0a62cb8598f0bbbbff854 100644 (file)
--- a/arch/mips/kernel/pm-cps.c
+++ b/arch/mips/kernel/pm-cps.c
@@ -57,10 +57,7 @@ static DEFINE_PER_CPU_ALIGNED(u32*, ready_count);
 /* Indicates online CPUs coupled with the current CPU */
 static DEFINE_PER_CPU_ALIGNED(cpumask_t, online_coupled);
 
-/*
- * Used to synchronize entry to deep idle states. Actually per-core rather
- * than per-CPU.
- */
+/* Used to synchronize entry to deep idle states */
 static DEFINE_PER_CPU_ALIGNED(atomic_t, pm_barrier);
 
 /* Saved CPU state across the CPS_PM_POWER_GATED state */
@@ -112,9 +109,10 @@ int cps_pm_enter_state(enum cps_pm_state state)
        cps_nc_entry_fn entry;
        struct core_boot_config *core_cfg;
        struct vpe_boot_config *vpe_cfg;
+       atomic_t *barrier;
 
        /* Check that there is an entry function for this state */
-       entry = per_cpu(nc_asm_enter, core)[state];
+       entry = per_cpu(nc_asm_enter, cpu)[state];
        if (!entry)
                return -EINVAL;
 
@@ -150,7 +148,7 @@ int cps_pm_enter_state(enum cps_pm_state state)
        smp_mb__after_atomic();
 
        /* Create a non-coherent mapping of the core ready_count */
-       core_ready_count = per_cpu(ready_count, core);
+       core_ready_count = per_cpu(ready_count, cpu);
        nc_addr = kmap_noncoherent(virt_to_page(core_ready_count),
                                   (unsigned long)core_ready_count);
        nc_addr += ((unsigned long)core_ready_count & ~PAGE_MASK);
@@ -158,7 +156,8 @@ int cps_pm_enter_state(enum cps_pm_state state)
 
        /* Ensure ready_count is zero-initialised before the assembly runs */
        WRITE_ONCE(*nc_core_ready_count, 0);
-       coupled_barrier(&per_cpu(pm_barrier, core), online);
+       barrier = &per_cpu(pm_barrier, cpumask_first(&cpu_sibling_map[cpu]));
+       coupled_barrier(barrier, online);
 
        /* Run the generated entry code */
        left = entry(online, nc_core_ready_count);
@@ -629,12 +628,14 @@ out_err:
 
 static int cps_pm_online_cpu(unsigned int cpu)
 {
-       enum cps_pm_state state;
-       unsigned core = cpu_core(&cpu_data[cpu]);
+       unsigned int sibling, core;
        void *entry_fn, *core_rc;
+       enum cps_pm_state state;
+
+       core = cpu_core(&cpu_data[cpu]);
 
        for (state = CPS_PM_NC_WAIT; state < CPS_PM_STATE_COUNT; state++) {
-               if (per_cpu(nc_asm_enter, core)[state])
+               if (per_cpu(nc_asm_enter, cpu)[state])
                        continue;
                if (!test_bit(state, state_support))
                        continue;
@@ -646,16 +647,19 @@ static int cps_pm_online_cpu(unsigned int cpu)
                        clear_bit(state, state_support);
                }
 
-               per_cpu(nc_asm_enter, core)[state] = entry_fn;
+               for_each_cpu(sibling, &cpu_sibling_map[cpu])
+                       per_cpu(nc_asm_enter, sibling)[state] = entry_fn;
        }
 
-       if (!per_cpu(ready_count, core)) {
+       if (!per_cpu(ready_count, cpu)) {
                core_rc = kmalloc(sizeof(u32), GFP_KERNEL);
                if (!core_rc) {
                        pr_err("Failed allocate core %u ready_count\n", core);
                        return -ENOMEM;
                }
-               per_cpu(ready_count, core) = core_rc;
+
+               for_each_cpu(sibling, &cpu_sibling_map[cpu])
+                       per_cpu(ready_count, sibling) = core_rc;
        }
 
        return 0;