The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 1874cb13d5d7cafa61ce93a760093ebc5485b6ab Mon Sep 17 00:00:00 2001
From: Alexander Gordeev agordeev@linux.ibm.com Date: Mon, 17 May 2021 08:18:12 +0200 Subject: [PATCH] s390/mcck: fix invalid KVM guest condition check
Wrong condition check is used to decide if a machine check hit while in KVM guest. As result of this check the instruction following the SIE critical section might be considered as still in KVM guest and _CIF_MCCK_GUEST CPU flag mistakenly set as result.
Fixes: c929500d7a5a ("s390/nmi: s390: New low level handling for machine check happening in guest") Cc: stable@vger.kernel.org Signed-off-by: Alexander Gordeev agordeev@linux.ibm.com Reviewed-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 3a81e38c95e7..9cc71ca9a88f 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -653,7 +653,7 @@ ENDPROC(stack_overflow) slgr %r9,%r13 lghi %r13,.Lsie_skip - .Lsie_entry clgr %r9,%r13 - jh .Lcleanup_sie_int + jhe .Lcleanup_sie_int oi __LC_CPU_FLAGS+7, _CIF_MCCK_GUEST .Lcleanup_sie_int: BPENTER __SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)