KVM: arm/arm64: Ensure vcpu target is unset on reset failure

A failed KVM_ARM_VCPU_INIT should not set the vcpu target,
as the vcpu target is used by kvm_vcpu_initialized() to
determine if other vcpu ioctls may proceed. We need to set
the target before calling kvm_reset_vcpu(), but if that call
fails, we should then unset it and clear the feature bitmap
while we're at it.

Signed-off-by: Andrew Jones <drjones@redhat.com>
[maz: Simplified patch, completed commit message]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 99c37384ba7b..f412ebc90610 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -934,7 +934,7 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
 static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
                                const struct kvm_vcpu_init *init)
 {
-        unsigned int i;
+        unsigned int i, ret;
         int phys_target = kvm_target_cpu();
 
         if (init->target != phys_target)
@@ -969,9 +969,14 @@ static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
         vcpu->arch.target = phys_target;
 
         /* Now we know what it is, we can reset it. */
-        return kvm_reset_vcpu(vcpu);
-}
+        ret = kvm_reset_vcpu(vcpu);
+        if (ret) {
+                vcpu->arch.target = -1;
+                bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
+        }
 
+        return ret;
+}
 
 static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
                                          struct kvm_vcpu_init *init)