Patch "KVM: s390: fix cmma migration for multiple memory slots" has been added to the 4.14-stable tree

Patch "KVM: s390: fix cmma migration for multiple memory slots" has been added to the 4.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    KVM: s390: fix cmma migration for multiple memory slots

to the 4.14-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:
     kvm-s390-fix-cmma-migration-for-multiple-memory-slots.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 32aa144fc32abfcbf7140f473dfbd94c5b9b4105 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Fri, 15 Dec 2017 13:14:31 +0100
Subject: KVM: s390: fix cmma migration for multiple memory slots

From: Christian Borntraeger <borntraeger@de.ibm.com>

commit 32aa144fc32abfcbf7140f473dfbd94c5b9b4105 upstream.

When multiple memory slots are present the cmma migration code
does not allocate enough memory for the bitmap. The memory slots
are sorted in reverse order, so we must use gfn and size of
slot[0] instead of the last one.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Fixes: 190df4a212a7 (KVM: s390: CMMA tracking, ESSA emulation, migration mode)
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/s390/kvm/kvm-s390.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -794,11 +794,12 @@ static int kvm_s390_vm_start_migration(s
 
 	if (kvm->arch.use_cmma) {
 		/*
-		 * Get the last slot. They should be sorted by base_gfn, so the
-		 * last slot is also the one at the end of the address space.
-		 * We have verified above that at least one slot is present.
+		 * Get the first slot. They are reverse sorted by base_gfn, so
+		 * the first slot is also the one at the end of the address
+		 * space. We have verified above that at least one slot is
+		 * present.
 		 */
-		ms = slots->memslots + slots->used_slots - 1;
+		ms = slots->memslots;
 		/* round up so we only use full longs */
 		ram_pages = roundup(ms->base_gfn + ms->npages, BITS_PER_LONG);
 		/* allocate enough bytes to store all the bits */


Patches currently in stable-queue which might be from borntraeger@de.ibm.com are

queue-4.14/kvm-s390-prevent-buffer-overrun-on-memory-hotplug-during-migration.patch
queue-4.14/kvm-s390-fix-cmma-migration-for-multiple-memory-slots.patch