s390: enable ARCH_HAS_MEMBARRIER_SYNC_CORE

s390 trivially supports the ARCH_HAS_MEMBARRIER_SYNC_CORE requirements
since the used lpswe(y) instruction to return from any kernel context to
user space performs CPU serialization. This is very similar to arm, arm64
and powerpc.

See commit 70216e18e519 ("membarrier: Provide core serializing command,
*_SYNC_CORE") for further details.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/Documentation/features/sched/membarrier-sync-core/arch-support.txt b/Documentation/features/sched/membarrier-sync-core/arch-support.txt
index 1e51614..23260ca 100644 (file)
--- a/Documentation/features/sched/membarrier-sync-core/arch-support.txt
+++ b/Documentation/features/sched/membarrier-sync-core/arch-support.txt
@@ -5,7 +5,7 @@
 #
 # Architecture requirements
 #
-# * arm/arm64/powerpc
+# * arm/arm64/powerpc/s390
 #
 # Rely on implicit context synchronization as a result of exception return
 # when returning from IPI handler, and when returning to user-space.
@@ -45,7 +45,7 @@
     |      parisc: | TODO |
     |     powerpc: |  ok  |
     |       riscv: | TODO |
-    |        s390: | TODO |
+    |        s390: |  ok  |
     |          sh: | TODO |
     |       sparc: | TODO |
     |          um: | TODO |

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 8f1c6da..d610f91 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -76,6 +76,7 @@ config S390
        select ARCH_HAS_GCOV_PROFILE_ALL
        select ARCH_HAS_GIGANTIC_PAGE
        select ARCH_HAS_KCOV
+       select ARCH_HAS_MEMBARRIER_SYNC_CORE
        select ARCH_HAS_MEM_ENCRYPT
        select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
        select ARCH_HAS_PTE_SPECIAL