Patch "s390/kvm: fix detection of guest machine checks" has been added to the 4.13-stable tree
Subsystems (2)
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 <[email protected]> know about it.
Quoted 1 line
From
0a5e2ec2647737907d267c09dc9a25fab1468865Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <[email protected]>
Date: Thu, 5 Oct 2017 08:29:47 +0200
Subject: s390/kvm: fix detection of guest machine checks
From: Martin Schwidefsky <[email protected]>
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.
--- arch/s390/kernel/entry.S | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
arch/s390/kernel/entry.S +5 -2
@@ -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 [email protected] are
queue-4.13/s390-kvm-fix-detection-of-guest-machine-checks.patch