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authorDavid Hildenbrand <dahi@linux.vnet.ibm.com>2016-03-03 08:48:47 (GMT)
committerChristian Borntraeger <borntraeger@de.ibm.com>2016-06-10 10:07:20 (GMT)
commitf9cbd9b02539330ddd349df583fcfc2db8a23b90 (patch)
treec4a49b793c57ec1cf50bf3ecc8a8442d4880de8a
parentc24cc9c8a6ca798427d3ff46b55df8403361df3e (diff)
downloadlinux-f9cbd9b02539330ddd349df583fcfc2db8a23b90.tar.xz
KVM: s390: provide CMMA attributes only if available
Let's not provide the device attribute for cmma enabling and clearing if the hardware doesn't support it. This also helps getting rid of the undocumented return value "-EINVAL" in case CMMA is not available when trying to enable it. Also properly document the meaning of -EINVAL for CMMA clearing. Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
-rw-r--r--Documentation/virtual/kvm/api.txt2
-rw-r--r--Documentation/virtual/kvm/devices/vm.txt3
-rw-r--r--arch/s390/kvm/kvm-s390.c7
3 files changed, 10 insertions, 2 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index a4482cc..4aac3e5 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2520,6 +2520,7 @@ Parameters: struct kvm_device_attr
Returns: 0 on success, -1 on error
Errors:
ENXIO: The group or attribute is unknown/unsupported for this device
+ or hardware support is missing.
EPERM: The attribute cannot (currently) be accessed this way
(e.g. read-only attribute, or attribute that only makes
sense when the device is in a different state)
@@ -2547,6 +2548,7 @@ Parameters: struct kvm_device_attr
Returns: 0 on success, -1 on error
Errors:
ENXIO: The group or attribute is unknown/unsupported for this device
+ or hardware support is missing.
Tests whether a device supports a particular attribute. A successful
return indicates the attribute is implemented. It does not necessarily
diff --git a/Documentation/virtual/kvm/devices/vm.txt b/Documentation/virtual/kvm/devices/vm.txt
index 8a458f4..b6cda49 100644
--- a/Documentation/virtual/kvm/devices/vm.txt
+++ b/Documentation/virtual/kvm/devices/vm.txt
@@ -20,7 +20,8 @@ Enables Collaborative Memory Management Assist (CMMA) for the virtual machine.
1.2. ATTRIBUTE: KVM_S390_VM_MEM_CLR_CMMA
Parameters: none
-Returns: 0
+Returns: -EINVAL if CMMA was not enabled
+ 0 otherwise
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/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 005e664..f695c6e 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -485,7 +485,7 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att
unsigned int idx;
switch (attr->attr) {
case KVM_S390_VM_MEM_ENABLE_CMMA:
- ret = -EINVAL;
+ ret = -ENXIO;
if (!sclp.has_cmma)
break;
@@ -499,6 +499,9 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att
mutex_unlock(&kvm->lock);
break;
case KVM_S390_VM_MEM_CLR_CMMA:
+ ret = -ENXIO;
+ if (!sclp.has_cmma)
+ break;
ret = -EINVAL;
if (!kvm->arch.use_cmma)
break;
@@ -964,6 +967,8 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
switch (attr->attr) {
case KVM_S390_VM_MEM_ENABLE_CMMA:
case KVM_S390_VM_MEM_CLR_CMMA:
+ ret = sclp.has_cmma ? 0 : -ENXIO;
+ break;
case KVM_S390_VM_MEM_LIMIT_SIZE:
ret = 0;
break;