/*
* Common checks before entering the guest world. Call with interrupts
* disabled.
*
* returns:
*
* == 1 if we're ready to go into guest state
* <= 0 if we need to go back to the host with return value
*/
int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
{
int r;
WARN_ON(irqs_disabled());
hard_irq_disable();
while (true) {
if (need_resched()) {
local_irq_enable();
cond_resched();
hard_irq_disable();
continue;
}
if (signal_pending(current)) {
kvmppc_account_exit(vcpu, SIGNAL_EXITS);
vcpu->run->exit_reason = KVM_EXIT_INTR;
r = -EINTR;
break;
}
vcpu->mode = IN_GUEST_MODE;
/*
* Reading vcpu->requests must happen after setting vcpu->mode,
* so we don't miss a request because the requester sees
* OUTSIDE_GUEST_MODE and assumes we'll be checking requests
* before next entering the guest (and thus doesn't IPI).
* This also orders the write to mode from any reads
* to the page tables done while the VCPU is running.
* Please see the comment in kvm_flush_remote_tlbs.
*/
smp_mb();
if (vcpu->requests) {
/* Make sure we process requests preemptable */
local_irq_enable();
trace_kvm_check_requests(vcpu);
r = kvmppc_core_check_requests(vcpu);
hard_irq_disable();
if (r > 0)
continue;
break;
}
if (kvmppc_core_prepare_to_enter(vcpu)) {
/* interrupts got enabled in between, so we
are back at square 1 */
continue;
}
guest_enter_irqoff();
return 1;
}
/* return to host */
local_irq_enable();
return r;
}
/*
* Common checks before entering the guest world. Call with interrupts
* disabled.
*
* returns:
*
* == 1 if we're ready to go into guest state
* <= 0 if we need to go back to the host with return value
*/
int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
{
int r = 1;
WARN_ON_ONCE(!irqs_disabled());
while (true) {
if (need_resched()) {
local_irq_enable();
cond_resched();
local_irq_disable();
continue;
}
if (signal_pending(current)) {
kvmppc_account_exit(vcpu, SIGNAL_EXITS);
vcpu->run->exit_reason = KVM_EXIT_INTR;
r = -EINTR;
break;
}
vcpu->mode = IN_GUEST_MODE;
/*
* Reading vcpu->requests must happen after setting vcpu->mode,
* so we don't miss a request because the requester sees
* OUTSIDE_GUEST_MODE and assumes we'll be checking requests
* before next entering the guest (and thus doesn't IPI).
*/
smp_mb();
if (vcpu->requests) {
/* Make sure we process requests preemptable */
local_irq_enable();
trace_kvm_check_requests(vcpu);
r = kvmppc_core_check_requests(vcpu);
local_irq_disable();
if (r > 0)
continue;
break;
}
if (kvmppc_core_prepare_to_enter(vcpu)) {
/* interrupts got enabled in between, so we
are back at square 1 */
continue;
}
#ifdef CONFIG_PPC64
/* lazy EE magic */
hard_irq_disable();
if (lazy_irq_pending()) {
/* Got an interrupt in between, try again */
local_irq_enable();
local_irq_disable();
kvm_guest_exit();
continue;
}
#endif
kvm_guest_enter();
break;
}
return r;
}
