@@ -624,9 +624,9 @@ int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
if (kvm_vm_is_protected(kvm))
kvm_call_hyp_nvhe(__pkvm_vcpu_init_traps, vcpu);
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->arch.config_lock);
set_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags);
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->arch.config_lock);
return ret;
}
@@ -957,7 +957,9 @@ int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu,
switch (attr->group) {
case KVM_ARM_VCPU_PMU_V3_CTRL:
+ mutex_lock(&vcpu->kvm->arch.config_lock);
ret = kvm_arm_pmu_v3_set_attr(vcpu, attr);
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
break;
case KVM_ARM_VCPU_TIMER_CTRL:
ret = kvm_arm_timer_set_attr(vcpu, attr);
@@ -377,7 +377,7 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
if (val & ~fw_reg_features)
return -EINVAL;
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->arch.config_lock);
if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags) &&
val != *fw_reg_bmap) {
@@ -387,7 +387,7 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
WRITE_ONCE(*fw_reg_bmap, val);
out:
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->arch.config_lock);
return ret;
}
@@ -875,7 +875,7 @@ static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id)
struct arm_pmu *arm_pmu;
int ret = -ENXIO;
- mutex_lock(&kvm->lock);
+ lockdep_assert_held(&kvm->arch.config_lock);
mutex_lock(&arm_pmus_lock);
list_for_each_entry(entry, &arm_pmus, entry) {
@@ -895,7 +895,6 @@ static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id)
}
mutex_unlock(&arm_pmus_lock);
- mutex_unlock(&kvm->lock);
return ret;
}
@@ -903,22 +902,20 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
{
struct kvm *kvm = vcpu->kvm;
+ lockdep_assert_held(&kvm->arch.config_lock);
+
if (!kvm_vcpu_has_pmu(vcpu))
return -ENODEV;
if (vcpu->arch.pmu.created)
return -EBUSY;
- mutex_lock(&kvm->lock);
if (!kvm->arch.arm_pmu) {
/* No PMU set, get the default one */
kvm->arch.arm_pmu = kvm_pmu_probe_armpmu();
- if (!kvm->arch.arm_pmu) {
- mutex_unlock(&kvm->lock);
+ if (!kvm->arch.arm_pmu)
return -ENODEV;
- }
}
- mutex_unlock(&kvm->lock);
switch (attr->attr) {
case KVM_ARM_VCPU_PMU_V3_IRQ: {
@@ -962,19 +959,13 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
filter.action != KVM_PMU_EVENT_DENY))
return -EINVAL;
- mutex_lock(&kvm->lock);
-
- if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags)) {
- mutex_unlock(&kvm->lock);
+ if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags))
return -EBUSY;
- }
if (!kvm->arch.pmu_filter) {
kvm->arch.pmu_filter = bitmap_alloc(nr_events, GFP_KERNEL_ACCOUNT);
- if (!kvm->arch.pmu_filter) {
- mutex_unlock(&kvm->lock);
+ if (!kvm->arch.pmu_filter)
return -ENOMEM;
- }
/*
* The default depends on the first applied filter.
@@ -993,8 +984,6 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
else
bitmap_clear(kvm->arch.pmu_filter, filter.base_event, filter.nevents);
- mutex_unlock(&kvm->lock);
-
return 0;
}
case KVM_ARM_VCPU_PMU_V3_SET_PMU: {
There are various bits of VM-scoped data that can only be configured before the first call to KVM_RUN, such as the hypercall bitmaps and the PMU. As these fields are protected by the kvm->lock and accessed while holding vcpu->mutex, this is yet another example of lock inversion. Change out the kvm->lock for kvm->arch.config_lock in all of these instances. Opportunistically simplify the locking mechanics of the PMU configuration by holding the config_lock for the entirety of kvm_arm_pmu_v3_set_attr(). Note that this also addresses a couple of bugs. There is an unguarded read of the PMU version in KVM_ARM_VCPU_PMU_V3_FILTER which could race with KVM_ARM_VCPU_PMU_V3_SET_PMU. Additionally, until now writes to the per-vCPU vPMU irq were not serialized VM-wide, meaning concurrent calls to KVM_ARM_VCPU_PMU_V3_IRQ could lead to a false positive in pmu_irq_is_valid(). Signed-off-by: Oliver Upton <oliver.upton@linux.dev> --- arch/arm64/kvm/arm.c | 4 ++-- arch/arm64/kvm/guest.c | 2 ++ arch/arm64/kvm/hypercalls.c | 4 ++-- arch/arm64/kvm/pmu-emul.c | 23 ++++++----------------- 4 files changed, 12 insertions(+), 21 deletions(-)