powerpc/cacheinfo: add cacheinfo_teardown, cacheinfo_rebuild

BugLink: https://bugs.launchpad.net/bugs/1863019
[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/powerpc/kernel/cacheinfo.c b/arch/powerpc/kernel/cacheinfo.c
index a8f20e5928e132588a4387b6260ef1884a7a920e..9edb454301336efb69fa8289fc7d2e49242dc0fb 100644 (file)
--- 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 955f5e999f1b81e8faad5a653f2777b0f65912c3..52bd3fc6642da11329abb3ec465f6709b897a651 100644 (file)
--- 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 */