From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:42226 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932318AbdJ3J3w (ORCPT ); Mon, 30 Oct 2017 05:29:52 -0400 Subject: Patch "s390/kvm: fix detection of guest machine checks" has been added to the 4.13-stable tree To: schwidefsky@de.ibm.com, borntraeger@de.ibm.com, gregkh@linuxfoundation.org Cc: , From: Date: Mon, 30 Oct 2017 10:29:39 +0100 Message-ID: <150935577916194@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled s390/kvm: fix detection of guest machine checks to the 4.13-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: s390-kvm-fix-detection-of-guest-machine-checks.patch and it can be found in the queue-4.13 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 0a5e2ec2647737907d267c09dc9a25fab1468865 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Thu, 5 Oct 2017 08:29:47 +0200 Subject: s390/kvm: fix detection of guest machine checks From: Martin Schwidefsky commit 0a5e2ec2647737907d267c09dc9a25fab1468865 upstream. The new detection code for guest machine checks added a check based on %r11 to .Lcleanup_sie to distinguish between normal asynchronous interrupts and machine checks. But the funtion is called from the program check handler as well with an undefined value in %r11. The effect is that all program exceptions pointing to the SIE instruction will set the CIF_MCCK_GUEST bit. The bit stays set for the CPU until the next machine check comes in which will incorrectly be interpreted as a guest machine check. The simplest fix is to stop using .Lcleanup_sie in the program check handler and duplicate a few instructions. Fixes: c929500d7a5a ("s390/nmi: s390: New low level handling for machine check happening in guest") Reviewed-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman --- arch/s390/kernel/entry.S | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -521,12 +521,15 @@ ENTRY(pgm_check_handler) tmhh %r8,0x0001 # test problem state bit jnz 2f # -> fault in user space #if IS_ENABLED(CONFIG_KVM) - # cleanup critical section for sie64a + # cleanup critical section for program checks in sie64a lgr %r14,%r9 slg %r14,BASED(.Lsie_critical_start) clg %r14,BASED(.Lsie_critical_length) jhe 0f - brasl %r14,.Lcleanup_sie + lg %r14,__SF_EMPTY(%r15) # get control block pointer + ni __SIE_PROG0C+3(%r14),0xfe # no longer in SIE + lctlg %c1,%c1,__LC_USER_ASCE # load primary asce + larl %r9,sie_exit # skip forward to sie_exit #endif 0: tmhh %r8,0x4000 # PER bit set in old PSW ? jnz 1f # -> enabled, can't be a double fault Patches currently in stable-queue which might be from schwidefsky@de.ibm.com are queue-4.13/s390-kvm-fix-detection-of-guest-machine-checks.patch