KVM: Dynamically allocate vcpus

This patch converts the vcpus array in "struct kvm" to a pointer
array, and changes the "vcpu_create" and "vcpu_setup" hooks into one
"vcpu_create" call which does the allocation and initialization of the
vcpu (calling back into the kvm_vcpu_init core helper).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 103 insertions, 95 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index bf8b8f030192..69d9ab4e7cb4 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -266,8 +266,10 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
         atomic_set(&completed, 0);
         cpus_clear(cpus);
         needed = 0;
-        for (i = 0; i < kvm->nvcpus; ++i) {
-                vcpu = &kvm->vcpus[i];
+        for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+                vcpu = kvm->vcpus[i];
+                if (!vcpu)
+                        continue;
                 if (test_and_set_bit(KVM_TLB_FLUSH, &vcpu->requests))
                         continue;
                 cpu = vcpu->cpu;
@@ -291,10 +293,61 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
         }
 }
 
+int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
+{
+        struct page *page;
+        int r;
+
+        mutex_init(&vcpu->mutex);
+        vcpu->cpu = -1;
+        vcpu->mmu.root_hpa = INVALID_PAGE;
+        vcpu->kvm = kvm;
+        vcpu->vcpu_id = id;
+
+        page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+        if (!page) {
+                r = -ENOMEM;
+                goto fail;
+        }
+        vcpu->run = page_address(page);
+
+        page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+        if (!page) {
+                r = -ENOMEM;
+                goto fail_free_run;
+        }
+        vcpu->pio_data = page_address(page);
+
+        vcpu->host_fx_image = (char*)ALIGN((hva_t)vcpu->fx_buf,
+                                           FX_IMAGE_ALIGN);
+        vcpu->guest_fx_image = vcpu->host_fx_image + FX_IMAGE_SIZE;
+
+        r = kvm_mmu_create(vcpu);
+        if (r < 0)
+                goto fail_free_pio_data;
+
+        return 0;
+
+fail_free_pio_data:
+        free_page((unsigned long)vcpu->pio_data);
+fail_free_run:
+        free_page((unsigned long)vcpu->run);
+fail:
+        return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_init);
+
+void kvm_vcpu_uninit(struct kvm_vcpu *vcpu)
+{
+        kvm_mmu_destroy(vcpu);
+        free_page((unsigned long)vcpu->pio_data);
+        free_page((unsigned long)vcpu->run);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_uninit);
+
 static struct kvm *kvm_create_vm(void)
 {
         struct kvm *kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL);
-        int i;
 
         if (!kvm)
                 return ERR_PTR(-ENOMEM);
@@ -303,14 +356,6 @@ static struct kvm *kvm_create_vm(void)
         spin_lock_init(&kvm->lock);
         INIT_LIST_HEAD(&kvm->active_mmu_pages);
         kvm_io_bus_init(&kvm->mmio_bus);
-        for (i = 0; i < KVM_MAX_VCPUS; ++i) {
-                struct kvm_vcpu *vcpu = &kvm->vcpus[i];
-
-                mutex_init(&vcpu->mutex);
-                vcpu->cpu = -1;
-                vcpu->kvm = kvm;
-                vcpu->mmu.root_hpa = INVALID_PAGE;
-        }
         spin_lock(&kvm_lock);
         list_add(&kvm->vm_list, &vm_list);
         spin_unlock(&kvm_lock);
@@ -367,30 +412,11 @@ static void free_pio_guest_pages(struct kvm_vcpu *vcpu)
 
 static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
 {
-        if (!vcpu->valid)
-                return;
-
         vcpu_load(vcpu);
         kvm_mmu_unload(vcpu);
         vcpu_put(vcpu);
 }
 
-static void kvm_free_vcpu(struct kvm_vcpu *vcpu)
-{
-        if (!vcpu->valid)
-                return;
-
-        vcpu_load(vcpu);
-        kvm_mmu_destroy(vcpu);
-        vcpu_put(vcpu);
-        kvm_arch_ops->vcpu_free(vcpu);
-        free_page((unsigned long)vcpu->run);
-        vcpu->run = NULL;
-        free_page((unsigned long)vcpu->pio_data);
-        vcpu->pio_data = NULL;
-        free_pio_guest_pages(vcpu);
-}
-
 static void kvm_free_vcpus(struct kvm *kvm)
 {
         unsigned int i;
@@ -399,9 +425,15 @@ static void kvm_free_vcpus(struct kvm *kvm)
          * Unpin any mmu pages first.
          */
         for (i = 0; i < KVM_MAX_VCPUS; ++i)
-                kvm_unload_vcpu_mmu(&kvm->vcpus[i]);
-        for (i = 0; i < KVM_MAX_VCPUS; ++i)
-                kvm_free_vcpu(&kvm->vcpus[i]);
+                if (kvm->vcpus[i])
+                        kvm_unload_vcpu_mmu(kvm->vcpus[i]);
+        for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+                if (kvm->vcpus[i]) {
+                        kvm_arch_ops->vcpu_free(kvm->vcpus[i]);
+                        kvm->vcpus[i] = NULL;
+                }
+        }
+
 }
 
 static int kvm_dev_release(struct inode *inode, struct file *filp)
@@ -2372,77 +2404,47 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
 {
         int r;
         struct kvm_vcpu *vcpu;
-        struct page *page;
 
-        r = -EINVAL;
         if (!valid_vcpu(n))
-                goto out;
-
-        vcpu = &kvm->vcpus[n];
-        vcpu->vcpu_id = n;
-
-        mutex_lock(&vcpu->mutex);
-
-        if (vcpu->valid) {
-                mutex_unlock(&vcpu->mutex);
-                return -EEXIST;
-        }
-
-        page = alloc_page(GFP_KERNEL | __GFP_ZERO);
-        r = -ENOMEM;
-        if (!page)
-                goto out_unlock;
-        vcpu->run = page_address(page);
-
-        page = alloc_page(GFP_KERNEL | __GFP_ZERO);
-        r = -ENOMEM;
-        if (!page)
-                goto out_free_run;
-        vcpu->pio_data = page_address(page);
-
-        vcpu->host_fx_image = (char*)ALIGN((hva_t)vcpu->fx_buf,
-                                           FX_IMAGE_ALIGN);
-        vcpu->guest_fx_image = vcpu->host_fx_image + FX_IMAGE_SIZE;
-        vcpu->cr0 = 0x10;
-
-        r = kvm_arch_ops->vcpu_create(vcpu);
-        if (r < 0)
-                goto out_free_vcpus;
+                return -EINVAL;
 
-        r = kvm_mmu_create(vcpu);
-        if (r < 0)
-                goto out_free_vcpus;
+        vcpu = kvm_arch_ops->vcpu_create(kvm, n);
+        if (IS_ERR(vcpu))
+                return PTR_ERR(vcpu);
 
-        kvm_arch_ops->vcpu_load(vcpu);
+        vcpu_load(vcpu);
         r = kvm_mmu_setup(vcpu);
-        if (r >= 0)
-                r = kvm_arch_ops->vcpu_setup(vcpu);
         vcpu_put(vcpu);
-
         if (r < 0)
-                goto out_free_vcpus;
+                goto free_vcpu;
 
+        spin_lock(&kvm->lock);
+        if (kvm->vcpus[n]) {
+                r = -EEXIST;
+                spin_unlock(&kvm->lock);
+                goto mmu_unload;
+        }
+        kvm->vcpus[n] = vcpu;
+        spin_unlock(&kvm->lock);
+
+        /* Now it's all set up, let userspace reach it */
         r = create_vcpu_fd(vcpu);
         if (r < 0)
-                goto out_free_vcpus;
-
-        spin_lock(&kvm_lock);
-        if (n >= kvm->nvcpus)
-                kvm->nvcpus = n + 1;
-        spin_unlock(&kvm_lock);
+                goto unlink;
+        return r;
 
-        vcpu->valid = 1;
+unlink:
+        spin_lock(&kvm->lock);
+        kvm->vcpus[n] = NULL;
+        spin_unlock(&kvm->lock);
 
-        return r;
+mmu_unload:
+        vcpu_load(vcpu);
+        kvm_mmu_unload(vcpu);
+        vcpu_put(vcpu);
 
-out_free_vcpus:
-        kvm_free_vcpu(vcpu);
-out_free_run:
-        free_page((unsigned long)vcpu->run);
-        vcpu->run = NULL;
-out_unlock:
-        mutex_unlock(&vcpu->mutex);
-out:
+free_vcpu:
+        kvm_arch_ops->vcpu_free(vcpu);
         return r;
 }
 
@@ -2935,9 +2937,12 @@ static void decache_vcpus_on_cpu(int cpu)
         int i;
 
         spin_lock(&kvm_lock);
-        list_for_each_entry(vm, &vm_list, vm_list)
+        list_for_each_entry(vm, &vm_list, vm_list) {
+                spin_lock(&vm->lock);
                 for (i = 0; i < KVM_MAX_VCPUS; ++i) {
-                        vcpu = &vm->vcpus[i];
+                        vcpu = vm->vcpus[i];
+                        if (!vcpu)
+                                continue;
                         /*
                          * If the vcpu is locked, then it is running on some
                          * other cpu and therefore it is not cached on the
@@ -2954,6 +2959,8 @@ static void decache_vcpus_on_cpu(int cpu)
                                 mutex_unlock(&vcpu->mutex);
                         }
                 }
+                spin_unlock(&vm->lock);
+        }
         spin_unlock(&kvm_lock);
 }
 
@@ -3078,8 +3085,9 @@ static u64 stat_get(void *_offset)
         spin_lock(&kvm_lock);
         list_for_each_entry(kvm, &vm_list, vm_list)
                 for (i = 0; i < KVM_MAX_VCPUS; ++i) {
-                        vcpu = &kvm->vcpus[i];
-                        total += *(u32 *)((void *)vcpu + offset);
+                        vcpu = kvm->vcpus[i];
+                        if (vcpu)
+                                total += *(u32 *)((void *)vcpu + offset);
                 }
         spin_unlock(&kvm_lock);
         return total;