make kernel bindings mutually exclusive

When the crate is built with --all-features we have a bunch of errors
because we are not excluding the 4.14 and 4.20 bindings. Whenever
all features is specified now, the 4.20 bindings are going to be
used. This change is required for switching to rust-vmm-ci where
the tests are run using --all-features flag.

Signed-off-by: Andreea Florescu <fandree@amazon.com>

Author: andreeaflorescu

src/arm/mod.rs

@@ -1,24 +1,25 @@
 // Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-#[cfg(feature = "kvm-v4_14_0")]
+// Export 4.14 bindings when the feature kvm-v4_20_0 is not specified.
+#[cfg(all(feature = "kvm-v4_14_0", not(feature = "kvm-v4_20_0")))]
 mod bindings_v4_14_0;
-#[cfg(feature = "kvm-v4_20_0")]
-mod bindings_v4_20_0;
 
-// Major hack to have a default version in case no feature is specified:
-// If no version is specified by using the features, just use the latest one
-// which currently is 4.20.
-#[cfg(all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0")))]
+// Export 4.20 bindings when kvm-v4_20_0 is specified or no kernel version
+// related features are specified.
+#[cfg(any(
+    feature = "kvm-v4_20_0",
+    all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0"))
+))]
 mod bindings_v4_20_0;
 
 pub mod bindings {
-    #[cfg(feature = "kvm-v4_14_0")]
+    #[cfg(all(feature = "kvm-v4_14_0", not(feature = "kvm-v4_20_0")))]
     pub use super::bindings_v4_14_0::*;
 
-    #[cfg(feature = "kvm-v4_20_0")]
-    pub use super::bindings_v4_20_0::*;
-
-    #[cfg(all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0")))]
+    #[cfg(any(
+        feature = "kvm-v4_20_0",
+        all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0"))
+    ))]
     pub use super::bindings_v4_20_0::*;
 }

src/arm64/mod.rs

@@ -1,24 +1,25 @@
 // Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-#[cfg(feature = "kvm-v4_14_0")]
+// Export 4.14 bindings when the feature kvm-v4_20_0 is not specified.
+#[cfg(all(feature = "kvm-v4_14_0", not(feature = "kvm-v4_20_0")))]
 mod bindings_v4_14_0;
-#[cfg(feature = "kvm-v4_20_0")]
-mod bindings_v4_20_0;
 
-// Major hack to have a default version in case no feature is specified:
-// If no version is specified by using the features, just use the latest one
-// which currently is 4.20.
-#[cfg(all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0")))]
+// Export 4.20 bindings when kvm-v4_20_0 is specified or no kernel version
+// related features are specified.
+#[cfg(any(
+    feature = "kvm-v4_20_0",
+    all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0"))
+))]
 mod bindings_v4_20_0;
 
 pub mod bindings {
-    #[cfg(feature = "kvm-v4_14_0")]
+    #[cfg(all(feature = "kvm-v4_14_0", not(feature = "kvm-v4_20_0")))]
     pub use super::bindings_v4_14_0::*;
 
-    #[cfg(feature = "kvm-v4_20_0")]
-    pub use super::bindings_v4_20_0::*;
-
-    #[cfg(all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0")))]
+    #[cfg(any(
+        feature = "kvm-v4_20_0",
+        all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0"))
+    ))]
     pub use super::bindings_v4_20_0::*;
 }

src/x86/mod.rs

@@ -4,25 +4,26 @@
 #[cfg(feature = "fam-wrappers")]
 mod fam_wrappers;
 
-#[cfg(feature = "kvm-v4_14_0")]
+// Export 4.14 bindings when the feature kvm-v4_20_0 is not specified.
+#[cfg(all(feature = "kvm-v4_14_0", not(feature = "kvm-v4_20_0")))]
 mod bindings_v4_14_0;
-#[cfg(feature = "kvm-v4_20_0")]
-mod bindings_v4_20_0;
 
-// Major hack to have a default version in case no feature is specified:
-// If no version is specified by using the features, just use the latest one
-// which currently is 4.20.
-#[cfg(all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0")))]
+// Export 4.20 bindings when kvm-v4_20_0 is specified or no kernel version
+// related features are specified.
+#[cfg(any(
+    feature = "kvm-v4_20_0",
+    all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0"))
+))]
 mod bindings_v4_20_0;
 
 pub mod bindings {
-    #[cfg(feature = "kvm-v4_14_0")]
+    #[cfg(all(feature = "kvm-v4_14_0", not(feature = "kvm-v4_20_0")))]
     pub use super::bindings_v4_14_0::*;
 
-    #[cfg(feature = "kvm-v4_20_0")]
-    pub use super::bindings_v4_20_0::*;
-
-    #[cfg(all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0")))]
+    #[cfg(any(
+        feature = "kvm-v4_20_0",
+        all(not(feature = "kvm-v4_14_0"), not(feature = "kvm-v4_20_0"))
+    ))]
     pub use super::bindings_v4_20_0::*;
 
     #[cfg(feature = "fam-wrappers")]