From: Andrew Jones <[email protected]> Fix potential races in kvm_psci_vcpu_on() by taking the kvm->lock mutex. In general, it's a bad idea to allow more than one PSCI_CPU_ON to process the same target VCPU at the same time. One such problem that may arise is that one PSCI_CPU_ON could be resetting the target vcpu, which fills the entire sys_regs array with a temporary value including the MPIDR register, while another looks up the VCPU based on the MPIDR value, resulting in no target VCPU found. Resolves both races found with the kvm-unit-tests/arm/psci unit test.
Reviewed-by: Marc Zyngier <[email protected]> Reviewed-by: Christoffer Dall <[email protected]> Reported-by: Levente Kurusa <[email protected]> Suggested-by: Christoffer Dall <[email protected]> Signed-off-by: Andrew Jones <[email protected]> Cc: [email protected] Signed-off-by: Christoffer Dall <[email protected]> --- arch/arm/kvm/psci.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c index c2b1315..a08d7a9 100644 --- a/arch/arm/kvm/psci.c +++ b/arch/arm/kvm/psci.c @@ -208,9 +208,10 @@ int kvm_psci_version(struct kvm_vcpu *vcpu) static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) { - int ret = 1; + struct kvm *kvm = vcpu->kvm; unsigned long psci_fn = vcpu_get_reg(vcpu, 0) & ~((u32) 0); unsigned long val; + int ret = 1; switch (psci_fn) { case PSCI_0_2_FN_PSCI_VERSION: @@ -230,7 +231,9 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) break; case PSCI_0_2_FN_CPU_ON: case PSCI_0_2_FN64_CPU_ON: + mutex_lock(&kvm->lock); val = kvm_psci_vcpu_on(vcpu); + mutex_unlock(&kvm->lock); break; case PSCI_0_2_FN_AFFINITY_INFO: case PSCI_0_2_FN64_AFFINITY_INFO: @@ -279,6 +282,7 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu) { + struct kvm *kvm = vcpu->kvm; unsigned long psci_fn = vcpu_get_reg(vcpu, 0) & ~((u32) 0); unsigned long val; @@ -288,7 +292,9 @@ static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu) val = PSCI_RET_SUCCESS; break; case KVM_PSCI_FN_CPU_ON: + mutex_lock(&kvm->lock); val = kvm_psci_vcpu_on(vcpu); + mutex_unlock(&kvm->lock); break; default: val = PSCI_RET_NOT_SUPPORTED; -- 2.9.0 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
