KVM: PPC: Book3S HV: Sanitize special-purpose register values on guest exit

[karo-tx-linux.git] / arch / powerpc / kvm / book3s_hv.c

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index cff207b72c46ae0b54cf48db5e4a3aa828f2fc29..baeddb06811d738a6ea8be4ce920e5ea39a9645a 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -833,6 +833,24 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu,
 
        vcpu->stat.sum_exits++;
 
+       /*
+        * This can happen if an interrupt occurs in the last stages
+        * of guest entry or the first stages of guest exit (i.e. after
+        * setting paca->kvm_hstate.in_guest to KVM_GUEST_MODE_GUEST_HV
+        * and before setting it to KVM_GUEST_MODE_HOST_HV).
+        * That can happen due to a bug, or due to a machine check
+        * occurring at just the wrong time.
+        */
+       if (vcpu->arch.shregs.msr & MSR_HV) {
+               printk(KERN_EMERG "KVM trap in HV mode!\n");
+               printk(KERN_EMERG "trap=0x%x | pc=0x%lx | msr=0x%llx\n",
+                       vcpu->arch.trap, kvmppc_get_pc(vcpu),
+                       vcpu->arch.shregs.msr);
+               kvmppc_dump_regs(vcpu);
+               run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+               run->hw.hardware_exit_reason = vcpu->arch.trap;
+               return RESUME_HOST;
+       }
        run->exit_reason = KVM_EXIT_UNKNOWN;
        run->ready_for_interrupt_injection = 1;
        switch (vcpu->arch.trap) {