KVM huge page backing support can not be easily tested under
s390. Currently testing is only possible after most of the guest has
already been set up.
To indicate, that KVM has huge page backing support, we add the
KVM_CAP_S390_HPAGE capability. This does not mean, that transparent
huge pages are supported.
Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx>
---
Documentation/virtual/kvm/api.txt | 10 ++++++++++
arch/s390/kvm/kvm-s390.c | 1 +
include/uapi/linux/kvm.h | 1 +
3 files changed, 12 insertions(+)
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 57d3ee9..a56b0af 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -4369,3 +4369,13 @@ Parameters: none
This capability indicates if the flic device will be able to get/set the
AIS states for migration via the KVM_DEV_FLIC_AISM_ALL attribute and allows
to discover this without having to create a flic device.
+
+8.14 KVM_CAP_S390_HPAGE
+
+Architectures: s390
+This capability, if KVM_CHECK_EXTENSION indicates that it is
+available, means that KVM supports VMs that are memory backed through
+hugetlbfs with 1 megabyte pages.
+
+While it is generally possible to create and start a VM without this
+support, the VM will not be functional.
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 73fb3bc..8951ad4 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -393,6 +393,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_S390_CMMA_MIGRATION:
case KVM_CAP_S390_AIS:
case KVM_CAP_S390_AIS_MIGRATION:
+ case KVM_CAP_S390_HPAGE:
r = 1;
break;
case KVM_CAP_S390_MEM_OP:
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 496e59a..aa3d707 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -932,6 +932,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_HYPERV_SYNIC2 148
#define KVM_CAP_HYPERV_VP_INDEX 149
#define KVM_CAP_S390_AIS_MIGRATION 150
+#define KVM_CAP_S390_HPAGE 151
#ifdef KVM_CAP_IRQ_ROUTING
--
2.7.4
--
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