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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>
Subject: [PATCH 5.12 133/178] s390/mcck: fix invalid KVM guest condition check
Date:   Mon, 21 Jun 2021 18:15:47 +0200
Message-Id: <20210621154927.309454936@linuxfoundation.org>
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From: Alexander Gordeev <agordeev@linux.ibm.com>

commit 1874cb13d5d7cafa61ce93a760093ebc5485b6ab upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/s390/kernel/entry.S |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -653,7 +653,7 @@ ENDPROC(stack_overflow)
 	slgr	%r9,%r13
 	larl	%r13,.Lsie_skip
 	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)