linux-kernel - [PATCH 3/3] KVM: s390: use kvm->created

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Date:	Mon, 13 Jun 2016 15:25:32 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:	Cornelia Huck <cornelia.huck@...ibm.com>,
	Christian Borntraeger <christian.borntraeger@...ibm.com>
Subject: [PATCH 3/3] KVM: s390: use kvm->created_vcpus

The new created_vcpus field avoids possible races between enabling
capabilities and creating VCPUs.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/s390/kvm/kvm-s390.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 43f2a2b80490..a3f845f25eff 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -355,7 +355,7 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
 		break;
 	case KVM_CAP_S390_VECTOR_REGISTERS:
 		mutex_lock(&kvm->lock);
-		if (atomic_read(&kvm->online_vcpus)) {
+		if (kvm->created_vcpus) {
 			r = -EBUSY;
 		} else if (MACHINE_HAS_VX) {
 			set_kvm_facility(kvm->arch.model.fac_mask, 129);
@@ -370,7 +370,7 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
 	case KVM_CAP_S390_RI:
 		r = -EINVAL;
 		mutex_lock(&kvm->lock);
-		if (atomic_read(&kvm->online_vcpus)) {
+		if (kvm->created_vcpus) {
 			r = -EBUSY;
 		} else if (test_facility(64)) {
 			set_kvm_facility(kvm->arch.model.fac_mask, 64);
@@ -426,7 +426,7 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att
 		ret = -EBUSY;
 		VM_EVENT(kvm, 3, "%s", "ENABLE: CMMA support");
 		mutex_lock(&kvm->lock);
-		if (atomic_read(&kvm->online_vcpus) == 0) {
+		if (kvm->created_vcpus) {
 			kvm->arch.use_cmma = 1;
 			ret = 0;
 		}
@@ -467,7 +467,7 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att
 
 		ret = -EBUSY;
 		mutex_lock(&kvm->lock);
-		if (atomic_read(&kvm->online_vcpus) == 0) {
+		if (kvm->created_vcpus) {
 			/* gmap_alloc will round the limit up */
 			struct gmap *new = gmap_alloc(current->mm, new_limit);
 
@@ -644,7 +644,7 @@ static int kvm_s390_set_processor(struct kvm *kvm, struct kvm_device_attr *attr)
 	int ret = 0;
 
 	mutex_lock(&kvm->lock);
-	if (atomic_read(&kvm->online_vcpus)) {
+	if (kvm->created_vcpus) {
 		ret = -EBUSY;
 		goto out;
 	}
-- 
1.8.3.1