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KVM: s390: Exploiting generic userspace interface for cmma

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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>
This commit is contained in:
Dominik Dingel 2014-04-09 13:13:00 +02:00 committed by Christian Borntraeger
parent b31605c12f
commit 4f718eab26
3 changed files with 66 additions and 0 deletions
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16
Documentation/virtual/kvm/devices/vm.txt
View file

@ -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.

7
arch/s390/include/uapi/asm/kvm.h
View file

@ -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 */

43
arch/s390/kvm/kvm-s390.c
View file

@ -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;