From: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
Documentation/virtual/kvm/api.txt | 2 ++
Documentation/virtual/kvm/devices/vm.txt | 3 ++-
arch/s390/kvm/kvm-s390.c | 7 ++++++-
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;
--
2.5.5
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