| From 6c7a5dce22b3f3cc44be098e2837fa6797edb8b8 Mon Sep 17 00:00:00 2001 |
| From: Andrew Jones <drjones@redhat.com> |
| Date: Tue, 18 Apr 2017 17:59:58 +0200 |
| Subject: [PATCH] KVM: arm/arm64: fix races in kvm_psci_vcpu_on |
| |
| commit 6c7a5dce22b3f3cc44be098e2837fa6797edb8b8 upstream. |
| |
| 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 <marc.zyngier@arm.com> |
| Reviewed-by: Christoffer Dall <cdall@linaro.org> |
| Reported-by: Levente Kurusa <lkurusa@redhat.com> |
| Suggested-by: Christoffer Dall <cdall@linaro.org> |
| Signed-off-by: Andrew Jones <drjones@redhat.com> |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Christoffer Dall <cdall@linaro.org> |
| |
| diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c |
| index c2b131527a64..a08d7a93aebb 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; |
| -- |
| 2.12.0 |
| |