Commit 7c2173a8 authored by Andrew Jones's avatar Andrew Jones Committed by Ben Hutchings

KVM: arm/arm64: fix races in kvm_psci_vcpu_on

commit 6c7a5dce 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: default avatarMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: default avatarChristoffer Dall <cdall@linaro.org>
Reported-by: default avatarLevente Kurusa <lkurusa@redhat.com>
Suggested-by: default avatarChristoffer Dall <cdall@linaro.org>
Signed-off-by: default avatarAndrew Jones <drjones@redhat.com>
Signed-off-by: default avatarChristoffer Dall <cdall@linaro.org>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 2c30708e
......@@ -191,9 +191,10 @@ 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_reg(vcpu, 0) & ~((u32) 0);
unsigned long val;
int ret = 1;
switch (psci_fn) {
case PSCI_0_2_FN_PSCI_VERSION:
......@@ -213,7 +214,9 @@ 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:
......@@ -269,6 +272,7 @@ 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_reg(vcpu, 0) & ~((u32) 0);
unsigned long val;
......@@ -278,7 +282,9 @@ 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;
case KVM_PSCI_FN_CPU_SUSPEND:
case KVM_PSCI_FN_MIGRATE:
......
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