[RFC PATCH v3 02/10] cpumask: Introduce cpu_paravirt_mask

[Shrikanth Hegde <sshegde@linux.ibm.com>]

This patch does
- Declare and Define cpu_paravirt_mask.
- Get/Set helpers for it.

It is not declared next to existing masks since that would cause too
many ifdefs. Still kept it in cpumask.h instead of sched.h
so any interested users can still see it when looking at other
cpumasks available.

Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
---
 include/linux/cpumask.h | 15 +++++++++++++++
 kernel/sched/core.c     |  5 +++++
 2 files changed, 20 insertions(+)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index ff8f41ab7ce6..afbc2ca5c1b7 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -1270,6 +1270,21 @@ static __always_inline bool cpu_dying(unsigned int cpu)
 
 #endif /* NR_CPUS > 1 */
 
+/*
+ * All related wrappers kept together to avoid too many ifdefs
+ * See Documentation/scheduler/sched-arch.rst for details
+ */
+#ifdef CONFIG_PARAVIRT
+extern struct cpumask __cpu_paravirt_mask;
+#define cpu_paravirt_mask    ((const struct cpumask *)&__cpu_paravirt_mask)
+#define set_cpu_paravirt(cpu, paravirt) assign_cpu((cpu), &__cpu_paravirt_mask, (paravirt))
+
+static __always_inline bool cpu_paravirt(unsigned int cpu)
+{
+	return cpumask_test_cpu(cpu, cpu_paravirt_mask);
+}
+#endif
+
 #define cpu_is_offline(cpu)	unlikely(!cpu_online(cpu))
 
 #if NR_CPUS <= BITS_PER_LONG
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index feb750aae71b..0f1e36bb5779 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -10963,3 +10963,8 @@ void sched_enq_and_set_task(struct sched_enq_and_set_ctx *ctx)
 		set_next_task(rq, ctx->p);
 }
 #endif /* CONFIG_SCHED_CLASS_EXT */
+
+#ifdef CONFIG_PARAVIRT
+struct cpumask __cpu_paravirt_mask __read_mostly;
+EXPORT_SYMBOL(__cpu_paravirt_mask);
+#endif
-- 
2.47.3