[PATCH v4] KVM: Factor out kvm_vcpu_kick to arch-generic code

[Christoffer Dall <c.dall@virtualopensystems.com>]

The kvm_vcpu_kick function performs roughly the same funcitonality on
most all architectures, so we shouldn't have separate copies.

PowerPC keeps a pointer to interchanging waitqueues on the vcpu_arch
structure and to accomodate this special need a
__KVM_HAVE_ARCH_VCPU_GET_WQ define and accompanying function
kvm_arch_vcpu_wq have been defined. For all other architectures this
is a generic inline that just returns &vcpu->wq;

This patch applies to d1c28f7568a74faacec896ee4f84afbffd20e5ab on
git://git.kernel.org/pub/scm/virt/kvm/kvm.git.

Changes since v3:
 - Doesn't try to generalize vcpu->mode across all architectures and
   instead calls kvm_arch_vcpu_should_kick, which is properly defined
   on x86 and ia64, but other architectures simply return 1 as to maintain
   status quo.

Changes since v2:
 - Restore arch-specific vcpu->cpu assignment to arch-specific code

Changes since v1:
 - Abstact CPU mode check into arch-specific function
 - Remove redundant vcpu->cpu assignment

Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
---
 arch/ia64/include/asm/kvm_host.h    |    1 +
 arch/ia64/kvm/kvm-ia64.c            |   20 +++++---------------
 arch/powerpc/include/asm/kvm_host.h |    6 ++++++
 arch/powerpc/kvm/powerpc.c          |   21 ++++++---------------
 arch/s390/kvm/kvm-s390.c            |    8 ++++++++
 arch/x86/kvm/x86.c                  |   16 ++--------------
 include/linux/kvm_host.h            |    9 +++++++++
 virt/kvm/kvm_main.c                 |   22 ++++++++++++++++++++++
 8 files changed, 59 insertions(+), 44 deletions(-)

diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h
index 2689ee5..06a5e91 100644
--- a/arch/ia64/include/asm/kvm_host.h
+++ b/arch/ia64/include/asm/kvm_host.h
@@ -365,6 +365,7 @@ struct thash_cb {
 };
 
 struct kvm_vcpu_stat {
+	u32 halt_wakeup;
 };
 
 struct kvm_vcpu_arch {
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 8ca7261..96dceaa 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1857,21 +1857,6 @@ void kvm_arch_hardware_unsetup(void)
 {
 }
 
-void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
-{
-	int me;
-	int cpu = vcpu->cpu;
-
-	if (waitqueue_active(&vcpu->wq))
-		wake_up_interruptible(&vcpu->wq);
-
-	me = get_cpu();
-	if (cpu != me && (unsigned) cpu < nr_cpu_ids && cpu_online(cpu))
-		if (!test_and_set_bit(KVM_REQ_KICK, &vcpu->requests))
-			smp_send_reschedule(cpu);
-	put_cpu();
-}
-
 int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq)
 {
 	return __apic_accept_irq(vcpu, irq->vector);
@@ -1941,6 +1926,11 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
 		(kvm_highest_pending_irq(vcpu) != -1);
 }
 
+int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
+{
+	return (!test_and_set_bit(KVM_REQ_KICK, &vcpu->requests));
+}
+
 int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
 				    struct kvm_mp_state *mp_state)
 {
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 1843d5d..d089969 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -495,4 +495,10 @@ struct kvm_vcpu_arch {
 #define KVM_MMIO_REG_QPR	0x0040
 #define KVM_MMIO_REG_FQPR	0x0060
 
+#define __KVM_HAVE_ARCH_VCPU_GET_WQ 1
+static inline wait_queue_head *kvm_arch_vcpu_wq(struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.wqp;
+}
+
 #endif /* __POWERPC_KVM_HOST_H__ */
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 0e21d15..b82e206 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -43,6 +43,11 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
 	       v->requests;
 }
 
+int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
+{
+	return 1;
+}
+
 int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
 {
 	int nr = kvmppc_get_gpr(vcpu, 11);
@@ -578,21 +583,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 	return r;
 }
 
-void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
-{
-	int me;
-	int cpu = vcpu->cpu;
-
-	me = get_cpu();
-	if (waitqueue_active(vcpu->arch.wqp)) {
-		wake_up_interruptible(vcpu->arch.wqp);
-		vcpu->stat.halt_wakeup++;
-	} else if (cpu != me && cpu != -1) {
-		smp_send_reschedule(vcpu->cpu);
-	}
-	put_cpu();
-}
-
 int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, struct kvm_interrupt *irq)
 {
 	if (irq->irq == KVM_INTERRUPT_UNSET) {
@@ -601,6 +591,7 @@ int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, struct kvm_interrupt *irq)
 	}
 
 	kvmppc_core_queue_external(vcpu, irq);
+
 	kvm_vcpu_kick(vcpu);
 
 	return 0;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 0b91679..aa907b7 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -422,6 +422,14 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
+int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
+{
+	/* kvm common code refers to this, but never calls it */
+	BUG();
+	return 0;
+}
+
+
 static int kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
 {
 	kvm_s390_vcpu_initial_reset(vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2bd77a3..244bc9a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6207,21 +6207,9 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
 		 kvm_cpu_has_interrupt(vcpu));
 }
 
-void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
+int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
-	int me;
-	int cpu = vcpu->cpu;
-
-	if (waitqueue_active(&vcpu->wq)) {
-		wake_up_interruptible(&vcpu->wq);
-		++vcpu->stat.halt_wakeup;
-	}
-
-	me = get_cpu();
-	if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu))
-		if (kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE)
-			smp_send_reschedule(cpu);
-	put_cpu();
+	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
 }
 
 int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9698080..f72e5f9 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -438,6 +438,7 @@ void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot,
 			     gfn_t gfn);
 
 void kvm_vcpu_block(struct kvm_vcpu *vcpu);
+void kvm_vcpu_kick(struct kvm_vcpu *vcpu);
 void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu);
 void kvm_resched(struct kvm_vcpu *vcpu);
 void kvm_load_guest_fpu(struct kvm_vcpu *vcpu);
@@ -506,6 +507,7 @@ int kvm_arch_hardware_setup(void);
 void kvm_arch_hardware_unsetup(void);
 void kvm_arch_check_processor_compat(void *rtn);
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu);
+int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu);
 
 void kvm_free_physmem(struct kvm *kvm);
 
@@ -521,6 +523,13 @@ static inline void kvm_arch_free_vm(struct kvm *kvm)
 }
 #endif
 
+#ifndef __KVM_HAVE_ARCH_VCPU_GET_WQ
+static inline wait_queue_head_t *kvm_arch_vcpu_wq(struct kvm_vcpu *vcpu)
+{
+	return &vcpu->wq;
+}
+#endif
+
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type);
 void kvm_arch_destroy_vm(struct kvm *kvm);
 void kvm_free_all_assigned_devices(struct kvm *kvm);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 470e305..b531928 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1562,6 +1562,28 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
 	finish_wait(&vcpu->wq, &wait);
 }
 
+/*
+ * Kick a sleeping VCPU, or a guest VCPU in guest mode, into host kernel mode.
+ */
+void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
+{
+	int me;
+	int cpu = vcpu->cpu;
+	wait_queue_head_t *wqp;
+
+	wqp = kvm_arch_vcpu_wq(vcpu);
+	if (waitqueue_active(wqp)) {
+		wake_up_interruptible(wqp);
+		++vcpu->stat.halt_wakeup;
+	}
+
+	me = get_cpu();
+	if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu))
+		if (kvm_arch_vcpu_should_kick(vcpu))
+			smp_send_reschedule(cpu);
+	put_cpu();
+}
+
 void kvm_resched(struct kvm_vcpu *vcpu)
 {
 	if (!need_resched())