[PATCH 03/29] KVM: add plane info to structs

[Paolo Bonzini <pbonzini@redhat.com>]

Add some of the data to move from one plane to the other within a VM,
typically from plane N to plane 0.

There is quite some difference here because while separate planes provide
very little of the vm file descriptor functionality, they are almost fully
functional vCPUs except that non-zero planes(*) can only be ran indirectly
through the initial plane.

Therefore, vCPUs use struct kvm_vcpu for all planes, with just a couple
fields that will be added later and will only be valid for plane 0.  At
the VM level instead plane info is stored in a completely different struct.
For now struct kvm_plane has no architecture-specific counterpart, but this
may change in the future if needed.  It's possible for example that some MMU
info becomes per-plane in order to support per-plane RWX permissions.

(*) I will restrain from calling them astral planes.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/linux/kvm_host.h  | 17 ++++++++++++++++-
 include/linux/kvm_types.h |  1 +
 virt/kvm/kvm_main.c       | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c8f1facdb600..0e16c34080ef 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -84,6 +84,10 @@
 #define KVM_MAX_NR_ADDRESS_SPACES	1
 #endif
 
+#ifndef KVM_MAX_VCPU_PLANES
+#define KVM_MAX_VCPU_PLANES		1
+#endif
+
 /*
  * For the normal pfn, the highest 12 bits should be zero,
  * so we can mask bit 62 ~ bit 52  to indicate the error pfn,
@@ -332,7 +336,8 @@ struct kvm_vcpu {
 #ifdef CONFIG_PROVE_RCU
 	int srcu_depth;
 #endif
-	int mode;
+	short plane;
+	short mode;
 	u64 requests;
 	unsigned long guest_debug;
 
@@ -367,6 +372,8 @@ struct kvm_vcpu {
 	} async_pf;
 #endif
 
+	struct kvm_vcpu *plane0;
+
 #ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
 	/*
 	 * Cpu relax intercept or pause loop exit optimization
@@ -753,6 +760,11 @@ struct kvm_memslots {
 	int node_idx;
 };
 
+struct kvm_plane {
+	struct kvm *kvm;
+	int plane;
+};
+
 struct kvm {
 #ifdef KVM_HAVE_MMU_RWLOCK
 	rwlock_t mmu_lock;
@@ -777,6 +789,9 @@ struct kvm {
 	/* The current active memslot set for each address space */
 	struct kvm_memslots __rcu *memslots[KVM_MAX_NR_ADDRESS_SPACES];
 	struct xarray vcpu_array;
+
+	struct kvm_plane *planes[KVM_MAX_VCPU_PLANES];
+
 	/*
 	 * Protected by slots_lock, but can be read outside if an
 	 * incorrect answer is acceptable.
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index 827ecc0b7e10..7d0a86108d1a 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -11,6 +11,7 @@ struct kvm_interrupt;
 struct kvm_irq_routing_table;
 struct kvm_memory_slot;
 struct kvm_one_reg;
+struct kvm_plane;
 struct kvm_run;
 struct kvm_userspace_memory_region;
 struct kvm_vcpu;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f6c947961b78..67773b6b9576 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1095,9 +1095,22 @@ void __weak kvm_arch_create_vm_debugfs(struct kvm *kvm)
 {
 }
 
+static struct kvm_plane *kvm_create_vm_plane(struct kvm *kvm, unsigned plane_id)
+{
+	struct kvm_plane *plane = kzalloc(sizeof(struct kvm_plane), GFP_KERNEL_ACCOUNT);
+
+	if (!plane)
+		return ERR_PTR(-ENOMEM);
+
+	plane->kvm = kvm;
+	plane->plane = plane_id;
+	return plane;
+}
+
 static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
 {
 	struct kvm *kvm = kvm_arch_alloc_vm();
+	struct kvm_plane *plane0;
 	struct kvm_memslots *slots;
 	int r, i, j;
 
@@ -1136,6 +1149,13 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
 	snprintf(kvm->stats_id, sizeof(kvm->stats_id), "kvm-%d",
 		 task_pid_nr(current));
 
+	plane0 = kvm_create_vm_plane(kvm, 0);
+	if (IS_ERR(plane0)) {
+		r = PTR_ERR(plane0);
+		goto out_err_no_plane0;
+	}
+	kvm->planes[0] = plane0;
+
 	r = -ENOMEM;
 	if (init_srcu_struct(&kvm->srcu))
 		goto out_err_no_srcu;
@@ -1227,6 +1247,8 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
 out_err_no_irq_srcu:
 	cleanup_srcu_struct(&kvm->srcu);
 out_err_no_srcu:
+	kfree(kvm->planes[0]);
+out_err_no_plane0:
 	kvm_arch_free_vm(kvm);
 	mmdrop(current->mm);
 	return ERR_PTR(r);
@@ -1253,6 +1275,10 @@ static void kvm_destroy_devices(struct kvm *kvm)
 	}
 }
 
+static void kvm_destroy_plane(struct kvm_plane *plane)
+{
+}
+
 static void kvm_destroy_vm(struct kvm *kvm)
 {
 	int i;
@@ -1309,6 +1335,11 @@ static void kvm_destroy_vm(struct kvm *kvm)
 #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES
 	xa_destroy(&kvm->mem_attr_array);
 #endif
+	for (i = 0; i < ARRAY_SIZE(kvm->planes); i++) {
+		struct kvm_plane *plane = kvm->planes[i];
+		if (plane)
+			kvm_destroy_plane(plane);
+	}
 	kvm_arch_free_vm(kvm);
 	preempt_notifier_dec();
 	kvm_disable_virtualization();
@@ -4110,6 +4141,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, unsigned long id)
 	}
 	vcpu->run = page_address(page);
 
+	vcpu->plane0 = vcpu;
 	kvm_vcpu_init(vcpu, kvm, id);
 
 	r = kvm_arch_vcpu_create(vcpu);
-- 
2.49.0