KVM: Simplify coalesced mmio initialization

- add destructor function
- move related allocation into constructor
- add stubs for !CONFIG_KVM_MMIO

Signed-off-by: Avi Kivity <avi@redhat.com>

3 files changed, 34 insertions, 8 deletions

diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index 04d69cd7049b..d68e6c68e0ff 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -92,11 +92,19 @@ static const struct kvm_io_device_ops coalesced_mmio_ops = {
 int kvm_coalesced_mmio_init(struct kvm *kvm)
 {
         struct kvm_coalesced_mmio_dev *dev;
+        struct page *page;
         int ret;
 
+        ret = -ENOMEM;
+        page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+        if (!page)
+                goto out_err;
+        kvm->coalesced_mmio_ring = page_address(page);
+
+        ret = -ENOMEM;
         dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
         if (!dev)
-                return -ENOMEM;
+                goto out_free_page;
         spin_lock_init(&dev->lock);
         kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
         dev->kvm = kvm;
@@ -104,11 +112,24 @@ int kvm_coalesced_mmio_init(struct kvm *kvm)
 
         ret = kvm_io_bus_register_dev(kvm, &kvm->mmio_bus, &dev->dev);
         if (ret < 0)
-                kfree(dev);
+                goto out_free_dev;
+
+        return ret;
 
+out_free_dev:
+        kfree(dev);
+out_free_page:
+        __free_page(page);
+out_err:
         return ret;
 }
 
+void kvm_coalesced_mmio_free(struct kvm *kvm)
+{
+        if (kvm->coalesced_mmio_ring)
+                free_page((unsigned long)kvm->coalesced_mmio_ring);
+}
+
 int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
                                          struct kvm_coalesced_mmio_zone *zone)
 {
diff --git a/virt/kvm/coalesced_mmio.h b/virt/kvm/coalesced_mmio.h
index e7033469733d..8a5959e3535f 100644
--- a/virt/kvm/coalesced_mmio.h
+++ b/virt/kvm/coalesced_mmio.h
@@ -10,6 +10,8 @@
  *
  */
 
+#ifdef CONFIG_KVM_MMIO
+
 #define KVM_COALESCED_MMIO_ZONE_MAX 100
 
 struct kvm_coalesced_mmio_dev {
@@ -21,9 +23,17 @@ struct kvm_coalesced_mmio_dev {
 };
 
 int kvm_coalesced_mmio_init(struct kvm *kvm);
+void kvm_coalesced_mmio_free(struct kvm *kvm);
 int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
                                        struct kvm_coalesced_mmio_zone *zone);
 int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
                                          struct kvm_coalesced_mmio_zone *zone);
 
+#else
+
+static inline int kvm_coalesced_mmio_init(struct kvm *kvm) { return 0; }
+static inline void kvm_coalesced_mmio_free(struct kvm *kvm) { }
+
+#endif
+
 #endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c10d117c4317..bc23b8e0609b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -51,9 +51,7 @@
 #include <asm/pgtable.h>
 #include <asm-generic/bitops/le.h>
 
-#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
 #include "coalesced_mmio.h"
-#endif
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/kvm.h>
@@ -468,10 +466,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
         kvm_free_irq_routing(kvm);
         kvm_io_bus_destroy(&kvm->pio_bus);
         kvm_io_bus_destroy(&kvm->mmio_bus);
-#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
-        if (kvm->coalesced_mmio_ring != NULL)
-                free_page((unsigned long)kvm->coalesced_mmio_ring);
-#endif
+        kvm_coalesced_mmio_free(kvm);
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
         mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
 #else