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authorAndrew Jones <drjones@redhat.com>2017-04-18 18:59:58 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-05-20 15:28:36 +0300
commit7b0d4391d0f4970601b21f56c540fc368bb8be06 (patch)
treebfa3aa35ef3d9f019a4fa63fc04e1cd17f60e618
parentbdf1d5b4c12959f4473e60cde44bfa1a2ebbf44f (diff)
downloadlinux-7b0d4391d0f4970601b21f56c540fc368bb8be06.tar.xz
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> Signed-off-by: Christoffer Dall <cdall@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/arm/kvm/psci.c8
1 files changed, 7 insertions, 1 deletions
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;