RE: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks

-----Original Message-----
From: kvm-owner@vger.kernel.org [mailto:kvm-owner@vger.kernel.org] On Beh=

alf Of

Alexander Graf
Sent: Friday, February 24, 2012 7:56 PM
To: kvm-ppc@vger.kernel.org
Cc: kvm@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; Wood Scott-B07421
Subject: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks
=20
Instead of checking whether we should reschedule only when we exited due =

to an

interrupt, let's always check before entering the guest back again. This =

gets

the target more in line with the other archs.
=20
Also while at it, generalize the whole thing so that eventually we could =

have a

single kvmppc_prepare_to_enter function for all ppc targets that does sig=

nal and

reschedule checking for us.
=20
Signed-off-by: Alexander Graf <redacted>
---
 arch/powerpc/include/asm/kvm_ppc.h |    2 +-
 arch/powerpc/kvm/book3s.c          |    4 ++-
 arch/powerpc/kvm/booke.c           |   70 ++++++++++++++++++++++++------=

-----

vcpu,

extern void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu);  exter=

n void

kvmppc_core_vcpu_put(struct kvm_vcpu *vcpu);
=20
-extern void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu);
+extern int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu);
 extern int kvmppc_core_pending_dec(struct kvm_vcpu *vcpu);  extern void
kvmppc_core_queue_program(struct kvm_vcpu *vcpu, ulong flags);  extern vo=

id

kvmppc_core_queue_dec(struct kvm_vcpu *vcpu); diff --git
a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index 7d54f4e..c8=

ead7b

gned

int priority)
 	return true;
 }
=20
-void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
+int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 {
 	unsigned long *pending =3D &vcpu->arch.pending_exceptions;
 	unsigned long old_pending =3D vcpu->arch.pending_exceptions; @@ -283,6
+283,8 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
=20
 	/* Tell the guest about our interrupt status */
 	kvmppc_update_int_pending(vcpu, *pending, old_pending);
+
+	return 0;
 }
=20
 pfn_t kvmppc_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn) diff --git
a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index 9979be1..3fce=

c2c

cpu

cpu)

 		local_irq_disable();
=20
 		kvmppc_set_exit_type(vcpu, EMULATED_MTMSRWE_EXITS);
-		kvmppc_core_check_exceptions(vcpu);
+		r =3D 1;
 	};
+
+	return r;
+}
+
+/*
+ * Common checks before entering the guest world.  Call with interrupts
+ * disabled.
+ *
+ * returns !0 if a signal is pending and check_signal is true  */
+static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu, bool
+check_signal) {
+	int r =3D 0;
+
+	WARN_ON_ONCE(!irqs_disabled());
+	while (true) {
+		if (need_resched()) {
+			local_irq_enable();
+			cond_resched();
+			local_irq_disable();
+			continue;
+		}
+
+		if (kvmppc_core_prepare_to_enter(vcpu)) {

kvmppc_prepare_to_enter() is called even on heavyweight_exit. Should not th=
is be called only on lightweight_exit?

Thanks
-Bharat

+			/* interrupts got enabled in between, so we
+			   are back at square 1 */
+			continue;
+		}
+
+		if (check_signal && signal_pending(current))
+			r =3D 1;
+
+		break;
+	}
+
+	return r;
 }
=20
 int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) @@ -=

470,10

+507,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *v=

cpu)

y of a

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