[PATCH AUTOSEL 4.19 415/671] powerpc/cacheinfo: add cacheinfo_teardown, cacheinfo_rebuild

Sasha Levin
2020-01-16T18:51:50Z

From: Nathan Lynch <nathanl@linux.ibm.com>

[ Upstream commit d4aa219a074a5abaf95a756b9f0d190b5c03a945 ]

Allow external callers to force the cacheinfo code to release all its
references to cache nodes, e.g. before processing device tree updates
post-migration, and to rebuild the hierarchy afterward.

CPU online/offline must be blocked by callers; enforce this.

Fixes: 410bccf97881 ("powerpc/pseries: Partition migration in the kernel")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/kernel/cacheinfo.c | 21 +++++++++++++++++++++
arch/powerpc/kernel/cacheinfo.h | 4 ++++
2 files changed, 25 insertions(+)

diff --git a/arch/powerpc/kernel/cacheinfo.c b/arch/powerpc/kernel/cacheinfo.c
index a8f20e5928e1..9edb45430133 100644
--- a/arch/powerpc/kernel/cacheinfo.c
+++ b/arch/powerpc/kernel/cacheinfo.c
@@ -865,4 +865,25 @@ void cacheinfo_cpu_offline(unsigned int cpu_id)
if (cache)
cache_cpu_clear(cache, cpu_id);
}
+
+void cacheinfo_teardown(void)
+{
+ unsigned int cpu;
+
+ lockdep_assert_cpus_held();
+
+ for_each_online_cpu(cpu)
+ cacheinfo_cpu_offline(cpu);
+}
+
+void cacheinfo_rebuild(void)
+{
+ unsigned int cpu;
+
+ lockdep_assert_cpus_held();
+
+ for_each_online_cpu(cpu)
+ cacheinfo_cpu_online(cpu);
+}
+
#endif /* (CONFIG_PPC_PSERIES && CONFIG_SUSPEND) || CONFIG_HOTPLUG_CPU */
diff --git a/arch/powerpc/kernel/cacheinfo.h b/arch/powerpc/kernel/cacheinfo.h
index 955f5e999f1b..52bd3fc6642d 100644
--- a/arch/powerpc/kernel/cacheinfo.h
+++ b/arch/powerpc/kernel/cacheinfo.h
@@ -6,4 +6,8 @@
extern void cacheinfo_cpu_online(unsigned int cpu_id);
extern void cacheinfo_cpu_offline(unsigned int cpu_id);

+/* Allow migration/suspend to tear down and rebuild the hierarchy. */
+extern void cacheinfo_teardown(void);
+extern void cacheinfo_rebuild(void);
+
#endif /* _PPC_CACHEINFO_H */
--
2.20.1