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authorDominik Dingel <dingel@linux.vnet.ibm.com>2014-04-09 13:13:00 +0200
committerChristian Borntraeger <borntraeger@de.ibm.com>2014-04-22 13:24:32 +0200
commit4f718eab262868aeab83774ec4ce25e6a9906657 (patch)
treee5913e863cea1909a1cac6b9f1cafcf4f57ef446
parentb31605c12f4edda7a40ad9f86985739666298c31 (diff)
KVM: s390: Exploiting generic userspace interface for cmma
To enable CMMA and to reset its state we use the vm kvm_device ioctls, encapsulating attributes within the KVM_S390_VM_MEM_CTRL group. Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
-rw-r--r--Documentation/virtual/kvm/devices/vm.txt16
-rw-r--r--arch/s390/include/uapi/asm/kvm.h7
-rw-r--r--arch/s390/kvm/kvm-s390.c43
3 files changed, 66 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/devices/vm.txt b/Documentation/virtual/kvm/devices/vm.txt
index 562bee6e600b..0d16f96c0eac 100644
--- a/Documentation/virtual/kvm/devices/vm.txt
+++ b/Documentation/virtual/kvm/devices/vm.txt
@@ -8,3 +8,19 @@ and controls.
The groups and attributes per virtual machine, if any, are architecture
specific.
+
+1. GROUP: KVM_S390_VM_MEM_CTRL
+Architectures: s390
+
+1.1. ATTRIBUTE: KVM_S390_VM_MEM_CTRL
+Parameters: none
+Returns: -EBUSY if already a vcpus is defined, otherwise 0
+
+Enables CMMA for the virtual machine
+
+1.2. ATTRIBUTE: KVM_S390_VM_CLR_CMMA
+Parameteres: none
+Returns: 0
+
+Clear the CMMA status for all guest pages, so any pages the guest marked
+as unused are again used any may not be reclaimed by the host.
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index c003c6a73b1e..e35c79821d29 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -54,6 +54,13 @@ struct kvm_s390_io_adapter_req {
__u64 addr;
};
+/* kvm attr_group on vm fd */
+#define KVM_S390_VM_MEM_CTRL 0
+
+/* kvm attributes for mem_ctrl */
+#define KVM_S390_VM_MEM_ENABLE_CMMA 0
+#define KVM_S390_VM_MEM_CLR_CMMA 1
+
/* for KVM_GET_REGS and KVM_SET_REGS */
struct kvm_regs {
/* general purpose regs for s390 */
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index fc2fe49488c0..fe2396cc0856 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -258,11 +258,43 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
return r;
}
+static int kvm_s390_mem_control(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+ int ret;
+ unsigned int idx;
+ switch (attr->attr) {
+ case KVM_S390_VM_MEM_ENABLE_CMMA:
+ ret = -EBUSY;
+ mutex_lock(&kvm->lock);
+ if (atomic_read(&kvm->online_vcpus) == 0) {
+ kvm->arch.use_cmma = 1;
+ ret = 0;
+ }
+ mutex_unlock(&kvm->lock);
+ break;
+ case KVM_S390_VM_MEM_CLR_CMMA:
+ mutex_lock(&kvm->lock);
+ idx = srcu_read_lock(&kvm->srcu);
+ page_table_reset_pgste(kvm->arch.gmap->mm, 0, TASK_SIZE, false);
+ srcu_read_unlock(&kvm->srcu, idx);
+ mutex_unlock(&kvm->lock);
+ ret = 0;
+ break;
+ default:
+ ret = -ENXIO;
+ break;
+ }
+ return ret;
+}
+
static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
{
int ret;
switch (attr->group) {
+ case KVM_S390_VM_MEM_CTRL:
+ ret = kvm_s390_mem_control(kvm, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -281,6 +313,17 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
int ret;
switch (attr->group) {
+ case KVM_S390_VM_MEM_CTRL:
+ switch (attr->attr) {
+ case KVM_S390_VM_MEM_ENABLE_CMMA:
+ case KVM_S390_VM_MEM_CLR_CMMA:
+ ret = 0;
+ break;
+ default:
+ ret = -ENXIO;
+ break;
+ }
+ break;
default:
ret = -ENXIO;
break;

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