powerpc/topology: Check if a core is online

topology_is_core_online() checks if the core a CPU belongs to
is online. The core is online if at least one of the sibling
CPUs is online. The first CPU of an online core is also online
in the common case, so this should be fairly quick.

Fixes: 73c58e7e1412 ("powerpc: Add HOTPLUG_SMT support")
Signed-off-by: Nysal Jan K.A <nysal@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240731030126.956210-3-nysal@linux.ibm.com

diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
index f4e6f2dd04b731ec3eb5154986a8aecd573dd8d0..16bacfe8c7a2ca1f97d403d2889e7135effbd978 100644 (file)
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h
@@ -145,6 +145,7 @@ static inline int cpu_to_coregroup_id(int cpu)
 
 #ifdef CONFIG_HOTPLUG_SMT
 #include <linux/cpu_smt.h>
+#include <linux/cpumask.h>
 #include <asm/cputhreads.h>
 
 static inline bool topology_is_primary_thread(unsigned int cpu)
@@ -156,6 +157,18 @@ static inline bool topology_smt_thread_allowed(unsigned int cpu)
 {
        return cpu_thread_in_core(cpu) < cpu_smt_num_threads;
 }
+
+#define topology_is_core_online topology_is_core_online
+static inline bool topology_is_core_online(unsigned int cpu)
+{
+       int i, first_cpu = cpu_first_thread_sibling(cpu);
+
+       for (i = first_cpu; i < first_cpu + threads_per_core; ++i) {
+               if (cpu_online(i))
+                       return true;
+       }
+       return false;
+}
 #endif
 
 #endif /* __KERNEL__ */