[PATCH 35/60] kvm: Add VCPU plane-scheduling state and helpers

[Jörg Rödel]

From: Joerg Roedel <joerg.roedel@xxxxxxx>

The algorithm is to always run the lowest runnable plane. Plane
switches are done by stopping the current plane and setting another
runnable.

Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
---
 include/linux/kvm_host.h | 16 ++++++++++++++
 virt/kvm/kvm_main.c      | 45 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 5c3f9dfa15ea..e3611e6cc3e4 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -168,6 +168,7 @@ static inline bool kvm_is_error_gpa(gpa_t gpa)
 #define KVM_REQ_VM_DEAD			(1 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
 #define KVM_REQ_UNBLOCK			2
 #define KVM_REQ_DIRTY_RING_SOFT_FULL	3
+#define KVM_REQ_PLANE_RESCHED		4
 #define KVM_REQUEST_ARCH_BASE		8
 
 /*
@@ -324,6 +325,8 @@ struct kvm_mmio_fragment {
 	unsigned int len;
 };
 
+
+
 struct kvm_vcpu_common {
 	struct kvm *kvm;
 
@@ -381,6 +384,8 @@ struct kvm_vcpu_common {
 
 	struct kvm_dirty_ring dirty_ring;
 
+	bool plane_switch;
+
 	struct kvm_vcpu_arch_common arch;
 };
 
@@ -388,6 +393,12 @@ struct kvm_vcpu_common {
 	for ((i) = 0; (i) < KVM_MAX_PLANES; ++(i))		\
 		if (((v) = common->vcpus[(i)]) != NULL)
 
+/* Tracked per plane-VCPU - used for deciding which plane-vcpu to run */
+enum kvm_vcpu_state {
+	STOPPED,
+	RUNNABLE,
+};
+
 struct kvm_vcpu {
 	struct kvm *kvm;
 	struct kvm_plane *plane;
@@ -401,6 +412,7 @@ struct kvm_vcpu {
 	struct kvm_run *run;
 
 	u64 plane_requests;
+	enum kvm_vcpu_state plane_state;
 
 	/* S390 only */
 	bool valid_wakeup;
@@ -440,6 +452,10 @@ struct kvm_vcpu {
 	unsigned plane_level;
 };
 
+void kvm_vcpu_set_plane_runnable(struct kvm_vcpu *vcpu);
+void kvm_vcpu_set_plane_stopped(struct kvm_vcpu *vcpu);
+struct kvm_vcpu *kvm_vcpu_select_plane(struct kvm_vcpu *vcpu);
+
 static inline bool kvm_vcpu_wants_to_run(struct kvm_vcpu *vcpu)
 {
 	return vcpu->common->wants_to_run;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9d30fd85ce5f..a30123b77112 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4397,6 +4397,7 @@ static int kvm_plane_ioctl_create_vcpu(struct kvm_plane *plane, unsigned long id
 	vcpu->vcpu_idx = vcpu->common->vcpu_idx;
 	vcpu->plane = plane;
 	vcpu->plane_level = plane->level;
+	vcpu->plane_state = STOPPED;
 	vcpu->run = vcpu->common->run;
 
 	kvm_vcpu_init(vcpu, kvm, id);
@@ -4938,6 +4939,50 @@ static struct file_operations kvm_plane_fops = {
 	KVM_COMPAT(kvm_plane_ioctl),
 };
 
+void kvm_vcpu_set_plane_runnable(struct kvm_vcpu *vcpu)
+{
+	vcpu->plane_state = RUNNABLE;
+	vcpu->common->plane_switch = true;
+	kvm_make_request(KVM_REQ_PLANE_RESCHED, vcpu);
+}
+EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_vcpu_set_plane_runnable);
+
+void kvm_vcpu_set_plane_stopped(struct kvm_vcpu *vcpu)
+{
+	vcpu->plane_state = STOPPED;
+	kvm_make_request(KVM_REQ_PLANE_RESCHED, vcpu);
+}
+EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_vcpu_set_plane_stopped);
+
+struct kvm_vcpu *kvm_vcpu_select_plane(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_common *common = vcpu->common;
+	struct kvm_vcpu *ret = NULL;
+	unsigned i;
+
+	for (i = 0; i < KVM_MAX_PLANES; i++) {
+		if (common->vcpus[i] == NULL)
+			continue;
+
+		if (common->vcpus[i]->plane_state == RUNNABLE) {
+			ret = common->vcpus[i];
+			break;
+		}
+	}
+
+	if (ret == NULL) {
+		ret = common->vcpus[0];
+		ret->plane_state = RUNNABLE;
+	}
+
+	common->current_vcpu = ret;
+
+	common->plane_switch = false;
+
+	return ret;
+}
+EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_vcpu_select_plane);
+
 static int kvm_device_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	struct kvm_device *dev = filp->private_data;
-- 
2.53.0