[patch 2/5] KVM: reintroduce guest mode bit and unify remote request code

[Marcelo Tosatti <mtosatti@redhat.com>]

[-- Attachment #1: reintroduce-guest-mode --]
[-- Type: text/plain, Size: 4840 bytes --]

Split KVM_REQ_KICKED in two bits: KVM_VCPU_KICKED, to indicate
whether a vcpu has been IPI'ed, and KVM_VCPU_GUEST_MODE, in a separate
vcpu_state variable.

Unify remote requests with kvm_vcpu_kick.

Synchronous requests wait on KVM_VCPU_GUEST_MODE, via wait_on_bit/wake_up_bit.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm/arch/x86/kvm/x86.c
===================================================================
--- kvm.orig/arch/x86/kvm/x86.c
+++ kvm/arch/x86/kvm/x86.c
@@ -3586,11 +3586,14 @@ static int vcpu_enter_guest(struct kvm_v
 
 	local_irq_disable();
 
-	clear_bit(KVM_REQ_KICK, &vcpu->requests);
-	smp_mb__after_clear_bit();
+	set_bit(KVM_VCPU_GUEST_MODE, &vcpu->vcpu_state);
+	barrier();
 
 	if (vcpu->requests || need_resched() || signal_pending(current)) {
-		set_bit(KVM_REQ_KICK, &vcpu->requests);
+		clear_bit(KVM_VCPU_KICKED, &vcpu->vcpu_state);
+		clear_bit(KVM_VCPU_GUEST_MODE, &vcpu->vcpu_state);
+		smp_mb__after_clear_bit();
+		wake_up_bit(&vcpu->vcpu_state, KVM_VCPU_GUEST_MODE);
 		local_irq_enable();
 		preempt_enable();
 		r = 1;
@@ -3642,7 +3645,10 @@ static int vcpu_enter_guest(struct kvm_v
 	set_debugreg(vcpu->arch.host_dr6, 6);
 	set_debugreg(vcpu->arch.host_dr7, 7);
 
-	set_bit(KVM_REQ_KICK, &vcpu->requests);
+	clear_bit(KVM_VCPU_KICKED, &vcpu->vcpu_state);
+	clear_bit(KVM_VCPU_GUEST_MODE, &vcpu->vcpu_state);
+	smp_mb__after_clear_bit();
+	wake_up_bit(&vcpu->vcpu_state, KVM_VCPU_GUEST_MODE);
 	local_irq_enable();
 
 	++vcpu->stat.exits;
Index: kvm/include/linux/kvm_host.h
===================================================================
--- kvm.orig/include/linux/kvm_host.h
+++ kvm/include/linux/kvm_host.h
@@ -42,6 +42,9 @@
 
 #define KVM_USERSPACE_IRQ_SOURCE_ID	0
 
+#define KVM_VCPU_GUEST_MODE        0
+#define KVM_VCPU_KICKED            1
+
 struct kvm;
 struct kvm_vcpu;
 extern struct kmem_cache *kvm_vcpu_cache;
@@ -83,6 +86,7 @@ struct kvm_vcpu {
 	int   cpu;
 	struct kvm_run *run;
 	unsigned long requests;
+	unsigned long vcpu_state;
 	unsigned long guest_debug;
 	int fpu_active;
 	int guest_fpu_loaded;
@@ -362,6 +366,7 @@ void kvm_arch_sync_events(struct kvm *kv
 
 int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu);
 void kvm_vcpu_kick(struct kvm_vcpu *vcpu);
+void kvm_vcpu_ipi(struct kvm_vcpu *vcpu);
 
 int kvm_is_mmio_pfn(pfn_t pfn);
 
Index: kvm/virt/kvm/kvm_main.c
===================================================================
--- kvm.orig/virt/kvm/kvm_main.c
+++ kvm/virt/kvm/kvm_main.c
@@ -119,18 +119,26 @@ void vcpu_put(struct kvm_vcpu *vcpu)
 
 void kvm_vcpu_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;
 	}
+	kvm_vcpu_ipi(vcpu);
+}
+
+void kvm_vcpu_ipi(struct kvm_vcpu *vcpu)
+{
+	int me;
+	int cpu = vcpu->cpu;
 
 	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);
+	if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
+		if (test_bit(KVM_VCPU_GUEST_MODE, &vcpu->vcpu_state)) {
+			if (!test_and_set_bit(KVM_VCPU_KICKED,
+					      &vcpu->vcpu_state))
+				smp_send_reschedule(cpu);
+		}
+	}
 	put_cpu();
 }
 
@@ -168,6 +176,30 @@ static bool make_all_cpus_request(struct
 	return called;
 }
 
+static int kvm_req_wait(void *unused)
+{
+	cpu_relax();
+	return 0;
+}
+
+static void kvm_vcpu_request(struct kvm_vcpu *vcpu, unsigned int req)
+{
+	set_bit(req, &vcpu->requests);
+	barrier();
+	kvm_vcpu_ipi(vcpu);
+	wait_on_bit(&vcpu->vcpu_state, KVM_VCPU_GUEST_MODE, kvm_req_wait,
+		    TASK_UNINTERRUPTIBLE);
+}
+
+static void kvm_vcpus_request(struct kvm *kvm, unsigned int req)
+{
+	int i;
+	struct kvm_vcpu *vcpu;
+
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		kvm_vcpu_request(vcpu, req);
+}
+
 void kvm_flush_remote_tlbs(struct kvm *kvm)
 {
 	if (make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))
Index: kvm/arch/ia64/kvm/kvm-ia64.c
===================================================================
--- kvm.orig/arch/ia64/kvm/kvm-ia64.c
+++ kvm/arch/ia64/kvm/kvm-ia64.c
@@ -655,12 +655,13 @@ again:
 	host_ctx = kvm_get_host_context(vcpu);
 	guest_ctx = kvm_get_guest_context(vcpu);
 
-	clear_bit(KVM_REQ_KICK, &vcpu->requests);
-
 	r = kvm_vcpu_pre_transition(vcpu);
 	if (r < 0)
 		goto vcpu_run_fail;
 
+	set_bit(KVM_VCPU_GUEST_MODE, &vcpu->vcpu_state);
+	barrier();
+
 	up_read(&vcpu->kvm->slots_lock);
 	kvm_guest_enter();
 
@@ -672,7 +673,10 @@ again:
 	kvm_vcpu_post_transition(vcpu);
 
 	vcpu->arch.launched = 1;
-	set_bit(KVM_REQ_KICK, &vcpu->requests);
+	clear_bit(KVM_VCPU_KICKED, &vcpu->vcpu_state);
+	clear_bit(KVM_VCPU_GUEST_MODE, &vcpu->vcpu_state);
+	smp_mb__after_clear_bit();
+	wake_up_bit(&vcpu->vcpu_state, KVM_VCPU_GUEST_MODE);
 	local_irq_enable();
 
 	/*

--