[PATCH RFC v3 4/9] KVM: arm/arm64: use locking helpers in kvm_vgic_create()

Radim Krčmář
2017-08-21T20:35:25Z

No new VCPUs can be created because we are holding the kvm->lock.
This means that if we successfuly lock all VCPUs, we'll be unlocking the
same set and there is no need to do extra bookkeeping.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
virt/kvm/arm/vgic/vgic-init.c | 24 +++++++++---------------
virt/kvm/arm/vgic/vgic-kvm-device.c | 6 +++++-
2 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index 5801261f3add..feb766f74c34 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -119,7 +119,7 @@ void kvm_vgic_vcpu_early_init(struct kvm_vcpu *vcpu)
*/
int kvm_vgic_create(struct kvm *kvm, u32 type)
{
- int i, vcpu_lock_idx = -1, ret;
+ int i, ret;
struct kvm_vcpu *vcpu;

if (irqchip_in_kernel(kvm))
@@ -140,18 +140,14 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
* vcpu->mutex. By grabbing the vcpu->mutex of all VCPUs we ensure
* that no other VCPUs are run while we create the vgic.
*/
- ret = -EBUSY;
- kvm_for_each_vcpu(i, vcpu, kvm) {
- if (!mutex_trylock(&vcpu->mutex))
- goto out_unlock;
- vcpu_lock_idx = i;
- }
+ if (!lock_all_vcpus(kvm))
+ return -EBUSY;

- kvm_for_each_vcpu(i, vcpu, kvm) {
- if (vcpu->arch.has_run_once)
+ kvm_for_each_vcpu(i, vcpu, kvm)
+ if (vcpu->arch.has_run_once) {
+ ret = -EBUSY;
goto out_unlock;
- }
- ret = 0;
+ }

if (type == KVM_DEV_TYPE_ARM_VGIC_V2)
kvm->arch.max_vcpus = VGIC_V2_MAX_CPUS;
@@ -176,11 +172,9 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
kvm->arch.vgic.vgic_cpu_base = VGIC_ADDR_UNDEF;
kvm->arch.vgic.vgic_redist_base = VGIC_ADDR_UNDEF;

+ ret = 0;
out_unlock:
- for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) {
- vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx);
- mutex_unlock(&vcpu->mutex);
- }
+ unlock_all_vcpus(kvm);
return ret;
}

diff --git a/virt/kvm/arm/vgic/vgic-kvm-device.c b/virt/kvm/arm/vgic/vgic-kvm-device.c
index 10ae6f394b71..c5124737c7fc 100644
--- a/virt/kvm/arm/vgic/vgic-kvm-device.c
+++ b/virt/kvm/arm/vgic/vgic-kvm-device.c
@@ -270,7 +270,11 @@ static void unlock_vcpus(struct kvm *kvm, int vcpu_lock_idx)

void unlock_all_vcpus(struct kvm *kvm)
{
- unlock_vcpus(kvm, atomic_read(&kvm->online_vcpus) - 1);
+ int i;
+ struct kvm_vcpu *tmp_vcpu;
+
+ kvm_for_each_vcpu(i, tmp_vcpu, kvm)
+ mutex_unlock(&tmp_vcpu->mutex);
}

/* Returns true if all vcpus were locked, false otherwise */
--
2.13.3