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authorDominik Dingel <dingel@linux.vnet.ibm.com>2014-10-31 14:10:41 +0100
committerChristian Borntraeger <borntraeger@de.ibm.com>2015-01-23 13:25:30 +0100
commit8c0a7ce60676caa89c204a1a3b748e065f3d7182 (patch)
tree8f3b3f85b3c99edb88933dd27c210916752aa75e /arch/s390/include/uapi/asm
parentdafd032a15f8f165a7d10e00217d3b74f70a7b0f (diff)
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KVM: s390: Allow userspace to limit guest memory size
With commit c6c956b80bdf ("KVM: s390/mm: support gmap page tables with less than 5 levels") we are able to define a limit for the guest memory size. As we round up the guest size in respect to the levels of page tables we get to guest limits of: 2048 MB, 4096 GB, 8192 TB and 16384 PB. We currently limit the guest size to 16 TB, which means we end up creating a page table structure supporting guest sizes up to 8192 TB. This patch introduces an interface that allows userspace to tune this limit. This may bring performance improvements for small guests. Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'arch/s390/include/uapi/asm')
-rw-r--r--arch/s390/include/uapi/asm/kvm.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 48eda3ab4944..9c01159cf667 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -61,6 +61,7 @@ struct kvm_s390_io_adapter_req {
/* kvm attributes for mem_ctrl */
#define KVM_S390_VM_MEM_ENABLE_CMMA 0
#define KVM_S390_VM_MEM_CLR_CMMA 1
+#define KVM_S390_VM_MEM_LIMIT_SIZE 2
/* for KVM_GET_REGS and KVM_SET_REGS */
struct kvm_regs {
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