[PATCH] KVM: PPC: Book3E 64: Fix IRQs warnings and hangs

[Mihai Caraman <mihai.caraman@xxxxxxxxxxxxx>]

A change in the generic code highlighted that we were running with IRQs
(soft) enabled on Book3E 64-bit when trying to restart interrupts from
handle_exit(). This is a lesson to configure lockdep often :)

There is no reason to exit guest with soft_enabled == 1, a local_irq_enable()
call will do this for us so get rid of kvmppc_layz_ee() calls. With this fix
we eliminate irqs_disabled() warnings and some guest and host hangs revealed
under stress tests, but guests still exhibit some unresponsiveness.

The unresponsiveness has to do with the fact that arch_local_irq_restore()
does not guarantees to hard enable interrupts. To do so replace exception
function calls like timer_interrupt() with irq_happened flags. The
local_irq_enable() call takes care of replaying them and lets the interrupts
hard enabled.

Signed-off-by: Mihai Caraman <mihai.caraman@xxxxxxxxxxxxx>
---
 arch/powerpc/kvm/booke.c |    9 +++------
 1 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 1020119..82f155e 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -673,7 +673,6 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 		ret = s;
 		goto out;
 	}
-	kvmppc_lazy_ee_enable();
 
 	kvm_guest_enter();
 
@@ -789,16 +788,16 @@ static void kvmppc_restart_interrupt(struct kvm_vcpu *vcpu,
 	switch (exit_nr) {
 	case BOOKE_INTERRUPT_EXTERNAL:
 		kvmppc_fill_pt_regs(&regs);
-		do_IRQ(&regs);
+		local_paca->irq_happened |= PACA_IRQ_EE;
 		break;
 	case BOOKE_INTERRUPT_DECREMENTER:
 		kvmppc_fill_pt_regs(&regs);
-		timer_interrupt(&regs);
+		local_paca->irq_happened |= PACA_IRQ_DEC;
 		break;
 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3E_64)
 	case BOOKE_INTERRUPT_DOORBELL:
 		kvmppc_fill_pt_regs(&regs);
-		doorbell_exception(&regs);
+		local_paca->irq_happened |= PACA_IRQ_DBELL;
 		break;
 #endif
 	case BOOKE_INTERRUPT_MACHINE_CHECK:
@@ -1148,8 +1147,6 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		if (s <= 0) {
 			local_irq_enable();
 			r = (s << 2) | RESUME_HOST | (r & RESUME_FLAG_NV);
-		} else {
-			kvmppc_lazy_ee_enable();
 		}
 	}
 
-- 
1.7.4.1


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