[PATCH 2/4] KVM: arm64: vgic: Wrap vgic_its_create() with config_lock

[Jean-Philippe Brucker]

vgic_its_create() changes the vgic state without holding the
config_lock, which triggers a lockdep warning in vgic_v4_init():

[  358.667941] WARNING: CPU: 3 PID: 178 at arch/arm64/kvm/vgic/vgic-v4.c:245 vgic_v4_init+0x15c/0x7a8
...
[  358.707410]  vgic_v4_init+0x15c/0x7a8
[  358.708550]  vgic_its_create+0x37c/0x4a4
[  358.709640]  kvm_vm_ioctl+0x1518/0x2d80
[  358.710688]  __arm64_sys_ioctl+0x7ac/0x1ba8
[  358.711960]  invoke_syscall.constprop.0+0x70/0x1e0
[  358.713245]  do_el0_svc+0xe4/0x2d4
[  358.714289]  el0_svc+0x44/0x8c
[  358.715329]  el0t_64_sync_handler+0xf4/0x120
[  358.716615]  el0t_64_sync+0x190/0x194

Wrap the whole of vgic_its_create() with config_lock since, in addition
to calling vgic_v4_init(), it also modifies the global kvm->arch.vgic
state.

Fixes: f00327731131 ("KVM: arm64: Use config_lock to protect vgic state")
Signed-off-by: Jean-Philippe Brucker <jean-philippe at linaro.org>
---
 arch/arm64/kvm/vgic/vgic-its.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 750e51e3779a3..5fe2365a629f2 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -1936,6 +1936,7 @@ void vgic_lpi_translation_cache_destroy(struct kvm *kvm)
 
 static int vgic_its_create(struct kvm_device *dev, u32 type)
 {
+	int ret;
 	struct vgic_its *its;
 
 	if (type != KVM_DEV_TYPE_ARM_VGIC_ITS)
@@ -1945,9 +1946,12 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)
 	if (!its)
 		return -ENOMEM;
 
+	mutex_lock(&dev->kvm->arch.config_lock);
+
 	if (vgic_initialized(dev->kvm)) {
-		int ret = vgic_v4_init(dev->kvm);
+		ret = vgic_v4_init(dev->kvm);
 		if (ret < 0) {
+			mutex_unlock(&dev->kvm->arch.config_lock);
 			kfree(its);
 			return ret;
 		}
@@ -1960,12 +1964,10 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)
 
 	/* Yep, even more trickery for lock ordering... */
 #ifdef CONFIG_LOCKDEP
-	mutex_lock(&dev->kvm->arch.config_lock);
 	mutex_lock(&its->cmd_lock);
 	mutex_lock(&its->its_lock);
 	mutex_unlock(&its->its_lock);
 	mutex_unlock(&its->cmd_lock);
-	mutex_unlock(&dev->kvm->arch.config_lock);
 #endif
 
 	its->vgic_its_base = VGIC_ADDR_UNDEF;
@@ -1986,7 +1988,11 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)
 
 	dev->private = its;
 
-	return vgic_its_set_abi(its, NR_ITS_ABIS - 1);
+	ret = vgic_its_set_abi(its, NR_ITS_ABIS - 1);
+
+	mutex_unlock(&dev->kvm->arch.config_lock);
+
+	return ret;
 }
 
 static void vgic_its_destroy(struct kvm_device *kvm_dev)
-- 
2.40.0