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authorDominik Dingel <dingel@linux.vnet.ibm.com>2014-12-01 17:24:42 +0100
committerChristian Borntraeger <borntraeger@de.ibm.com>2015-12-15 17:08:21 +0100
commita3a92c31bf0b57ad0ca7f092a6f3a57168ba9ae2 (patch)
tree1e8fd0810ebeb5331a8cb3ec700b023a17162aaa /Documentation/virtual/kvm
parentKVM: s390: obey kptr_restrict in traces (diff)
downloadlinux-a3a92c31bf0b57ad0ca7f092a6f3a57168ba9ae2.tar.xz
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KVM: s390: fix mismatch between user and in-kernel guest limit
While the userspace interface requests the maximum size the gmap code expects to get a maximum address. This error resulted in bigger page tables than necessary for some guest sizes, e.g. a 2GB guest used 3 levels instead of 2. At the same time we introduce KVM_S390_NO_MEM_LIMIT, which allows in a bright future that a guest spans the complete 64 bit address space. We also switch to TASK_MAX_SIZE for the initial memory size, this is a cosmetic change as the previous size also resulted in a 4 level pagetable creation. Reported-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'Documentation/virtual/kvm')
-rw-r--r--Documentation/virtual/kvm/devices/vm.txt3
1 files changed, 2 insertions, 1 deletions
diff --git a/Documentation/virtual/kvm/devices/vm.txt b/Documentation/virtual/kvm/devices/vm.txt
index 2d09d1ed86d0..f083a168eb35 100644
--- a/Documentation/virtual/kvm/devices/vm.txt
+++ b/Documentation/virtual/kvm/devices/vm.txt
@@ -37,7 +37,8 @@ Returns: -EFAULT if the given address is not accessible
Allows userspace to query the actual limit and set a new limit for
the maximum guest memory size. The limit will be rounded up to
2048 MB, 4096 GB, 8192 TB respectively, as this limit is governed by
-the number of page table levels.
+the number of page table levels. In the case that there is no limit we will set
+the limit to KVM_S390_NO_MEM_LIMIT (U64_MAX).
2. GROUP: KVM_S390_VM_CPU_MODEL
Architectures: s390