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authorChristoffer Dall <christoffer.dall@linaro.org>2016-08-09 19:13:01 +0200
committerRadim Krčmář <rkrcmar@redhat.com>2016-08-12 12:01:27 +0200
commita28ebea2adc4a2bef5989a5a181ec238f59fbcad (patch)
tree2ce115dec973b4383b64a33a999b7396e9b8f8e8 /virt
parent023e9fddc3616b005c3753fc1bb6526388cd7a30 (diff)
downloadlinux-stericsson-a28ebea2adc4a2bef5989a5a181ec238f59fbcad.tar.gz
KVM: Protect device ops->create and list_add with kvm->lock
KVM devices were manipulating list data structures without any form of synchronization, and some implementations of the create operations also suffered from a lack of synchronization. Now when we've split the xics create operation into create and init, we can hold the kvm->lock mutex while calling the create operation and when manipulating the devices list. The error path in the generic code gets slightly ugly because we have to take the mutex again and delete the device from the list, but holding the mutex during anon_inode_getfd or releasing/locking the mutex in the common non-error path seemed wrong. Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/arm/vgic/vgic-init.c17
-rw-r--r--virt/kvm/kvm_main.c13
2 files changed, 16 insertions, 14 deletions
diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index fb4b0a79a950..83777c1cbae0 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -73,12 +73,8 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
int i, vcpu_lock_idx = -1, ret;
struct kvm_vcpu *vcpu;
- mutex_lock(&kvm->lock);
-
- if (irqchip_in_kernel(kvm)) {
- ret = -EEXIST;
- goto out;
- }
+ if (irqchip_in_kernel(kvm))
+ return -EEXIST;
/*
* This function is also called by the KVM_CREATE_IRQCHIP handler,
@@ -87,10 +83,8 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
* the proper checks already.
*/
if (type == KVM_DEV_TYPE_ARM_VGIC_V2 &&
- !kvm_vgic_global_state.can_emulate_gicv2) {
- ret = -ENODEV;
- goto out;
- }
+ !kvm_vgic_global_state.can_emulate_gicv2)
+ return -ENODEV;
/*
* Any time a vcpu is run, vcpu_load is called which tries to grab the
@@ -138,9 +132,6 @@ out_unlock:
vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx);
mutex_unlock(&vcpu->mutex);
}
-
-out:
- mutex_unlock(&kvm->lock);
return ret;
}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ae642452e91a..195078225aa5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -696,6 +696,11 @@ static void kvm_destroy_devices(struct kvm *kvm)
{
struct kvm_device *dev, *tmp;
+ /*
+ * We do not need to take the kvm->lock here, because nobody else
+ * has a reference to the struct kvm at this point and therefore
+ * cannot access the devices list anyhow.
+ */
list_for_each_entry_safe(dev, tmp, &kvm->devices, vm_node) {
list_del(&dev->vm_node);
dev->ops->destroy(dev);
@@ -2832,11 +2837,15 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
dev->ops = ops;
dev->kvm = kvm;
+ mutex_lock(&kvm->lock);
ret = ops->create(dev, cd->type);
if (ret < 0) {
+ mutex_unlock(&kvm->lock);
kfree(dev);
return ret;
}
+ list_add(&dev->vm_node, &kvm->devices);
+ mutex_unlock(&kvm->lock);
if (ops->init)
ops->init(dev);
@@ -2844,10 +2853,12 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
ret = anon_inode_getfd(ops->name, &kvm_device_fops, dev, O_RDWR | O_CLOEXEC);
if (ret < 0) {
ops->destroy(dev);
+ mutex_lock(&kvm->lock);
+ list_del(&dev->vm_node);
+ mutex_unlock(&kvm->lock);
return ret;
}
- list_add(&dev->vm_node, &kvm->devices);
kvm_get_kvm(kvm);
cd->fd = ret;
return 0;