diff --git a/lib/vagrant/plugin/v2.rb b/lib/vagrant/plugin/v2.rb
index 917caf7a6..91803e648 100644
--- a/lib/vagrant/plugin/v2.rb
+++ b/lib/vagrant/plugin/v2.rb
@@ -1,5 +1,8 @@
 require "log4r"
 
+# We don't autoload components because if we're loading anything in the
+# V2 namespace anyways, then we're going to need the Components class.
+require "vagrant/plugin/v2/components"
 require "vagrant/plugin/v2/errors"
 
 module Vagrant
diff --git a/lib/vagrant/plugin/v2/components.rb b/lib/vagrant/plugin/v2/components.rb
new file mode 100644
index 000000000..b982b8c0a
--- /dev/null
+++ b/lib/vagrant/plugin/v2/components.rb
@@ -0,0 +1,14 @@
+module Vagrant
+  module Plugin
+    module V2
+      # This is the container class for the components of a single plugin.
+      class Components
+        attr_reader :provider_configs
+
+        def initialize
+          @provider_configs = Registry.new
+        end
+      end
+    end
+  end
+end
diff --git a/lib/vagrant/plugin/v2/manager.rb b/lib/vagrant/plugin/v2/manager.rb
index 88f8e2b2a..18ec2e013 100644
--- a/lib/vagrant/plugin/v2/manager.rb
+++ b/lib/vagrant/plugin/v2/manager.rb
@@ -55,25 +55,6 @@ module Vagrant
           result
         end
 
-        # This returns all the registered configuration classes that were
-        # marked as "upgrade safe."
-        #
-        # @return [Hash]
-        def config_upgrade_safe
-          result = {}
-
-          @registered.each do |plugin|
-            configs = plugin.data[:config_upgrade_safe]
-            if configs
-              configs.each do |key|
-                result[key] = plugin.config.get(key)
-              end
-            end
-          end
-
-          result
-        end
-
         # This returns all the registered guests.
         #
         # @return [Hash]
@@ -113,6 +94,19 @@ module Vagrant
           providers
         end
 
+        # This returns all the config classes for the various providers.
+        #
+        # @return [Hash]
+        def provider_configs
+          configs = {}
+
+          @registered.each do |plugin|
+            configs.merge!(plugin.components.provider_configs.to_hash)
+          end
+
+          configs
+        end
+
         # This returns all registered provisioners.
         #
         # @return [Hash]
diff --git a/lib/vagrant/plugin/v2/plugin.rb b/lib/vagrant/plugin/v2/plugin.rb
index 26134572b..28a27a026 100644
--- a/lib/vagrant/plugin/v2/plugin.rb
+++ b/lib/vagrant/plugin/v2/plugin.rb
@@ -2,6 +2,8 @@ require "set"
 
 require "log4r"
 
+require "vagrant/plugin/v2/components"
+
 module Vagrant
   module Plugin
     module V2
@@ -25,6 +27,13 @@ module Vagrant
           @manager ||= Manager.new
         end
 
+        # Returns the {Components} for this plugin.
+        #
+        # @return [Components]
+        def self.components
+          @components ||= Components.new
+        end
+
         # Set the name of the plugin. The moment that this is called, the
         # plugin will be registered and available. Before this is called, a
         # plugin does not exist. The name must be unique among all installed
@@ -118,24 +127,21 @@ module Vagrant
         # without breaking anything in future versions of Vagrant.
         #
         # @param [String] name Configuration key.
-        # @param [Boolean] upgrade_safe If this is true, then this configuration
-        #   key is safe to load during an upgrade, meaning that it depends
-        #   on NO Vagrant internal classes. Do _not_ set this to true unless
-        #   you really know what you're doing, since you can cause Vagrant
-        #   to crash (although Vagrant will output a user-friendly error
-        #   message if this were to happen).
-        def self.config(name=UNSET_VALUE, upgrade_safe=false, &block)
+        # XXX: Document options hash
+        def self.config(name=UNSET_VALUE, options=nil, &block)
           data[:config] ||= Registry.new
 
           # Register a new config class only if a name was given.
           if name != UNSET_VALUE
-            data[:config].register(name.to_sym, &block)
+            options ||= {}
 
-            # If we were told this is an upgrade safe configuration class
-            # then we add it to the set.
-            if upgrade_safe
-              data[:config_upgrade_safe] ||= Set.new
-              data[:config_upgrade_safe].add(name.to_sym)
+            if options[:provider]
+              # This config is for a specific provider. Register it as
+              # a provider config component.
+              components.provider_configs.register(name.to_sym, &block)
+            else
+              # This is a generic configuration plugin, register it as such.
+              data[:config].register(name.to_sym, &block)
             end
           end
 
diff --git a/plugins/kernel_v2/config/vm.rb b/plugins/kernel_v2/config/vm.rb
index 818b09350..9e3c1379f 100644
--- a/plugins/kernel_v2/config/vm.rb
+++ b/plugins/kernel_v2/config/vm.rb
@@ -29,7 +29,7 @@ module VagrantPlugins
         @forwarded_ports = []
         @shared_folders = {}
         @networks = []
-        @providers = []
+        @providers = {}
         @provisioners = []
         @customizations = []
       end
@@ -76,8 +76,9 @@ module VagrantPlugins
       # Configures a provider for this VM.
       #
       # @param [Symbol] name The name of the provider.
-      def provider(name)
-        @providers << VagrantConfigProvider.new(name)
+      def provider(name, &block)
+        # TODO: Error if a provider is defined multiple times.
+        @providers[name] = VagrantConfigProvider.new(name, block)
       end
 
       def provision(name, options=nil, &block)
diff --git a/plugins/kernel_v2/config/vm_provider.rb b/plugins/kernel_v2/config/vm_provider.rb
index ae326b1f3..cb1abac1e 100644
--- a/plugins/kernel_v2/config/vm_provider.rb
+++ b/plugins/kernel_v2/config/vm_provider.rb
@@ -1,16 +1,48 @@
+require "log4r"
+
+require "vagrant/util/stacked_proc_runner"
+
 module VagrantPlugins
   module Kernel_V2
     # Represents a single configured provider for a VM. This may or may
-    # not be a valid provider.
+    # not be a valid provider. Validation is deferred until later.
     class VagrantConfigProvider
       attr_reader :name
+      attr_reader :config
 
       # Initializes a new provider configuration for a VM. This should
       # only be instantiated internally by calling `config.vm.provider`.
       #
       # @param [Symbol] name The name of the provider that is registered.
-      def initialize(name)
-        @name = name
+      def initialize(name, block)
+        @name   = name
+        @config = nil
+        @logger = Log4r::Logger.new("vagrant::config::vm::provider")
+
+        # If we were given a block to configure with, then let's try
+        # to do that.
+        load_config(block) if block
+      end
+
+      protected
+
+      # This takes the config block given to define the provider and
+      # attempts to turn this into a real configuration object. If the
+      # provider plugin is not found then it is simply ignored. This allows
+      # people to share Vagrantfiles that have configuration for providers
+      # which may not be setup on every user's system.
+      #
+      # @param [Proc] config_proc
+      def load_config(config_proc)
+        config_class = Vagrant.plugin("2").manager.provider_configs[@name]
+        if !config_class
+          @logger.info("Provider config for #{@name} not found, ignoring that config.")
+          return
+        end
+
+        @logger.info("Configuring provider #{@name} with #{config_class}")
+        @config = config_class.new
+        config_proc.call(@config)
       end
     end
   end
diff --git a/plugins/kernel_v2/plugin.rb b/plugins/kernel_v2/plugin.rb
index 36b6233b6..55cfcc0dc 100644
--- a/plugins/kernel_v2/plugin.rb
+++ b/plugins/kernel_v2/plugin.rb
@@ -11,31 +11,31 @@ module VagrantPlugins
       basic functionality of Vagrant version 2.
       DESC
 
-      # Core configuration keys provided by the kernel. Note that all
-      # the kernel configuration classes are marked as _upgrade safe_ (the
-      # true 2nd param). This means that these can be loaded in ANY version
-      # of the core of Vagrant.
-      config("ssh", true) do
+      # Core configuration keys provided by the kernel. Note that unlike
+      # "kernel_v1", none of these configuration classes are upgradable.
+      # This is by design, since we can't be sure if they're upgradable
+      # until another version is available.
+      config("ssh") do
         require File.expand_path("../config/ssh", __FILE__)
         SSHConfig
       end
 
-      config("nfs", true) do
+      config("nfs") do
         require File.expand_path("../config/nfs", __FILE__)
         NFSConfig
       end
 
-      config("package", true) do
+      config("package") do
         require File.expand_path("../config/package", __FILE__)
         PackageConfig
       end
 
-      config("vagrant", true) do
+      config("vagrant") do
         require File.expand_path("../config/vagrant", __FILE__)
         VagrantConfig
       end
 
-      config("vm", true) do
+      config("vm") do
         require File.expand_path("../config/vm", __FILE__)
         VMConfig
       end
diff --git a/test/unit/vagrant/plugin/v2/components_test.rb b/test/unit/vagrant/plugin/v2/components_test.rb
new file mode 100644
index 000000000..30c2df403
--- /dev/null
+++ b/test/unit/vagrant/plugin/v2/components_test.rb
@@ -0,0 +1,9 @@
+require File.expand_path("../../../../base", __FILE__)
+
+describe Vagrant::Plugin::V2::Components do
+  let(:instance) { described_class.new }
+
+  it "should have provider configs" do
+    instance.provider_configs.should be_kind_of(Vagrant::Registry)
+  end
+end
diff --git a/test/unit/vagrant/plugin/v2/manager_test.rb b/test/unit/vagrant/plugin/v2/manager_test.rb
index 0929bc5f0..46d044ece 100644
--- a/test/unit/vagrant/plugin/v2/manager_test.rb
+++ b/test/unit/vagrant/plugin/v2/manager_test.rb
@@ -45,22 +45,6 @@ describe Vagrant::Plugin::V2::Manager do
     instance.config[:bar].should == "baz"
   end
 
-  it "should enumerate registered upgrade safe config classes" do
-    pA = plugin do |p|
-      p.config("foo", true) { "bar" }
-    end
-
-    pB = plugin do |p|
-      p.config("bar") { "baz" }
-    end
-
-    instance.register(pA)
-    instance.register(pB)
-
-    instance.config_upgrade_safe.length.should == 1
-    instance.config_upgrade_safe[:foo].should == "bar"
-  end
-
   it "should enumerate registered guest classes" do
     pA = plugin do |p|
       p.guest("foo") { "bar" }
@@ -111,4 +95,22 @@ describe Vagrant::Plugin::V2::Manager do
     instance.providers[:foo].should == "bar"
     instance.providers[:bar].should == "baz"
   end
+
+  it "provides the collection of registered provider configs" do
+    pA = plugin do |p|
+      p.config("foo", :provider => true) { "foo" }
+    end
+
+    pB = plugin do |p|
+      p.config("bar", :provider => true) { "bar" }
+      p.config("baz") { "baz" }
+    end
+
+    instance.register(pA)
+    instance.register(pB)
+
+    instance.provider_configs.length.should == 2
+    instance.provider_configs[:foo].should == "foo"
+    instance.provider_configs[:bar].should == "bar"
+  end
 end
diff --git a/test/unit/vagrant/plugin/v2/plugin_test.rb b/test/unit/vagrant/plugin/v2/plugin_test.rb
index c12cc32b0..d6acb0128 100644
--- a/test/unit/vagrant/plugin/v2/plugin_test.rb
+++ b/test/unit/vagrant/plugin/v2/plugin_test.rb
@@ -126,6 +126,14 @@ describe Vagrant::Plugin::V2::Plugin do
         plugin.config[:foo]
       }.to raise_error(StandardError)
     end
+
+    it "should register configuration classes for providers" do
+      plugin = Class.new(described_class) do
+        config("foo", :provider => true) { "bar" }
+      end
+
+      plugin.components.provider_configs[:foo].should == "bar"
+    end
   end
 
   describe "easy commands" do