[ 3.5.y.z extended stable ] Patch "s390/kvm: dont announce RRBM support" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    s390/kvm: dont announce RRBM support

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 97df6fd06f0c5fdda5e6084fd5452360a9fc2b31 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger at de.ibm.com>
Date: Tue, 2 Oct 2012 16:25:38 +0200
Subject: [PATCH] s390/kvm: dont announce RRBM support

commit 87cac8f879a5ecd7109dbe688087e8810b3364eb upstream.

Newer kernels (linux-next with the transparent huge page patches)
use rrbm if the feature is announced via feature bit 66.
RRBM will cause intercepts, so KVM does not handle it right now,
causing an illegal instruction in the guest.
The  easy solution is to disable the feature bit for the guest.

This fixes bugs like:
Kernel BUG at 0000000000124c2a [verbose debug info unavailable]
illegal operation: 0001 [#1] SMP
Modules linked in: virtio_balloon virtio_net ipv6 autofs4
CPU: 0 Not tainted 3.5.4 #1
Process fmempig (pid: 659, task: 000000007b712fd0, ksp: 000000007bed3670)
Krnl PSW : 0704d00180000000 0000000000124c2a (pmdp_clear_flush_young+0x5e/0x80)
     R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 EA:3
     00000000003cc000 0000000000000004 0000000000000000 0000000079800000
     0000000000040000 0000000000000000 000000007bed3918 000000007cf40000
     0000000000000001 000003fff7f00000 000003d281a94000 000000007bed383c
     000000007bed3918 00000000005ecbf8 00000000002314a6 000000007bed36e0
 Krnl Code:>0000000000124c2a: b9810025          ogr     %r2,%r5
           0000000000124c2e: 41343000           la      %r3,0(%r4,%r3)
           0000000000124c32: a716fffa           brct    %r1,124c26
           0000000000124c36: b9010022           lngr    %r2,%r2
           0000000000124c3a: e3d0f0800004       lg      %r13,128(%r15)
           0000000000124c40: eb22003f000c       srlg    %r2,%r2,63
[ 2150.713198] Call Trace:
[ 2150.713223] ([<00000000002312c4>] page_referenced_one+0x6c/0x27c)
[ 2150.713749]  [<0000000000233812>] page_referenced+0x32a/0x410
[...]

CC: Alex Graf <agraf at suse.de>
Signed-off-by: Martin Schwidefsky <schwidefsky at de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger at de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti at redhat.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 arch/s390/kvm/kvm-s390.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 664766d..cea9701 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -981,7 +981,7 @@ static int __init kvm_s390_init(void)
 	}
 	memcpy(facilities, S390_lowcore.stfle_fac_list, 16);
 	facilities[0] &= 0xff00fff3f47c0000ULL;
-	facilities[1] &= 0x201c000000000000ULL;
+	facilities[1] &= 0x001c000000000000ULL;
 	return 0;
 }

--
1.7.9.5