vmm: Deprecate static CPU templates

CHANGELOG.md

@@ -48,6 +48,11 @@
 - Added support for the /dev/userfaultfd device available on linux kernels >=
   6.1. This is the default for creating UFFD handlers on these kernel versions.
   If it is unavailable, Firecracker falls back to the userfaultfd syscall.
+- Deprecated `cpu_template` field in `PUT` and `PATCH` requests on `/machine-config`
+  API, which is used to set a static CPU template. Custom CPU templates added in
+  v1.4.0 are available as an improved iteration of the static CPU templates. For
+  more information about the transition from static CPU templates to custom CPU
+  templates, please refer to [this GitHub discussion](https://github.com/firecracker-microvm/firecracker/discussions/4135).
 
 ### Fixed
 

docs/api-change-runbook.md

@@ -247,9 +247,6 @@ Firecracker API.
   * Update any relevant documentation.
 * We update the python integration tests to reflect the change (reference
   implementation in [this commit][4]).
-  * We find the relevant resource in `tests/framework/resources.py` and
-    update its API, in this case by making the `vsock_id` parameter optional
-    in `Vsock.create_json()`.
   * We refactor the relevant
     `tests/integration_tests/functional/test_api.py` test to use the artifact
     model instead of the fixture one. If the test already uses the artifact

docs/cpu_templates/cpu-templates.md

@@ -34,6 +34,13 @@ Firecracker supports two types of CPU templates:
 - Custom CPU templates - users can create their own CPU templates in json
   format and pass them to Firecracker
 
+> **Note**
+Static CPU templates are deprecated starting from v1.5.0 and will be removed in
+accordance with our deprecation policy. Even after the removal, custom CPU
+templates are available as an improved iteration of static CPU templates. For
+more information about the transition from static CPU templates to custom CPU
+templates, please refer to [this GitHub discussion](https://github.com/firecracker-microvm/firecracker/discussions/4135).
+
 > **Note**
 CPU templates for ARM (both static and custom) require the following patch
 to be available in the host kernel: [Support writable CPU ID registers from userspace](https://lore.kernel.org/kvm/20230212215830.2975485-1-jingzhangos@google.com/#t).

src/api_server/src/lib.rs

@@ -227,21 +227,21 @@ mod tests {
     /// test deserialization and logging.
     #[cfg(target_arch = "x86_64")]
     const TEST_UNESCAPED_JSON_TEMPLATE: &str = r#"{
-      "msr_modifiers": [
-        {
-          "addr": "0x0\n\n\n\nTEST\n\n\n\n",
-          "bitmap": "0b00"
-        }
-      ]
+        "msr_modifiers": [
+            {
+                "addr": "0x0\n\n\n\nTEST\n\n\n\n",
+                "bitmap": "0b00"
+            }
+        ]
     }"#;
     #[cfg(target_arch = "aarch64")]
     pub const TEST_UNESCAPED_JSON_TEMPLATE: &str = r#"{
-      "reg_modifiers": [
-        {
-          "addr": "0x0\n\n\n\nTEST\n\n\n\n",
-          "bitmap": "0b00"
-        }
-      ]
+        "reg_modifiers": [
+            {
+                "addr": "0x0\n\n\n\nTEST\n\n\n\n",
+                "bitmap": "0b00"
+            }
+        ]
     }"#;
 
     #[test]

src/api_server/src/request/balloon.rs

@@ -69,82 +69,82 @@ mod tests {
 
         // PATCH with invalid fields.
         let body = r#"{
-                "amount_mib": "bar",
-                "foo": "bar"
-              }"#;
+            "amount_mib": "bar",
+            "foo": "bar"
+        }"#;
         assert!(parse_patch_balloon(&Body::new(body), None).is_err());
 
         // PATCH with invalid types on fields. Adding a polling interval as string instead of bool.
         let body = r#"{
-                "amount_mib": 1000,
-                "stats_polling_interval_s": "false"
-              }"#;
+            "amount_mib": 1000,
+            "stats_polling_interval_s": "false"
+        }"#;
         let res = parse_patch_balloon(&Body::new(body), None);
         assert!(res.is_err());
 
         // PATCH with invalid types on fields. Adding a amount_mib as a negative number.
         let body = r#"{
-                "amount_mib": -1000,
-                "stats_polling_interval_s": true
-              }"#;
+            "amount_mib": -1000,
+            "stats_polling_interval_s": true
+        }"#;
         let res = parse_patch_balloon(&Body::new(body), None);
         assert!(res.is_err());
 
         // PATCH on statistics with missing ppolling interval field.
         let body = r#"{
-                "amount_mib": 100
-              }"#;
+            "amount_mib": 100
+        }"#;
         let res = parse_patch_balloon(&Body::new(body), Some("statistics"));
         assert!(res.is_err());
 
         // PATCH with missing amount_mib field.
         let body = r#"{
-                "stats_polling_interval_s": 0
-              }"#;
+            "stats_polling_interval_s": 0
+        }"#;
         let res = parse_patch_balloon(&Body::new(body), None);
         assert!(res.is_err());
 
         // PATCH that tries to update something else other than allowed fields.
         let body = r#"{
-                "amount_mib": "dummy_id",
-                "stats_polling_interval_s": "dummy_host"
-              }"#;
+            "amount_mib": "dummy_id",
+            "stats_polling_interval_s": "dummy_host"
+        }"#;
         let res = parse_patch_balloon(&Body::new(body), None);
         assert!(res.is_err());
 
         // PATCH with payload that is not a json.
         let body = r#"{
-                "fields": "dummy_field"
-              }"#;
+            "fields": "dummy_field"
+        }"#;
         assert!(parse_patch_balloon(&Body::new(body), None).is_err());
 
         // PATCH on unrecognized path.
         let body = r#"{
             "fields": "dummy_field"
-          }"#;
+        }"#;
         assert!(parse_patch_balloon(&Body::new(body), Some("config")).is_err());
 
         let body = r#"{
-                "amount_mib": 1
-              }"#;
-        #[allow(clippy::match_wild_err_arm)]
-        match vmm_action_from_request(parse_patch_balloon(&Body::new(body), None).unwrap()) {
-            VmmAction::UpdateBalloon(balloon_cfg) => assert_eq!(balloon_cfg.amount_mib, 1),
-            _ => panic!("Test failed: Invalid parameters"),
-        };
+            "amount_mib": 1
+        }"#;
+        let expected_config = BalloonUpdateConfig { amount_mib: 1 };
+        assert_eq!(
+            vmm_action_from_request(parse_patch_balloon(&Body::new(body), None).unwrap()),
+            VmmAction::UpdateBalloon(expected_config)
+        );
 
         let body = r#"{
-                "stats_polling_interval_s": 1
-            }"#;
-        #[allow(clippy::match_wild_err_arm)]
-        match vmm_action_from_request(
-            parse_patch_balloon(&Body::new(body), Some("statistics")).unwrap(),
-        ) {
-            VmmAction::UpdateBalloonStatistics(balloon_cfg) => {
-                assert_eq!(balloon_cfg.stats_polling_interval_s, 1)
-            }
-            _ => panic!("Test failed: Invalid parameters"),
+            "stats_polling_interval_s": 1
+        }"#;
+        let expected_config = BalloonUpdateStatsConfig {
+            stats_polling_interval_s: 1,
         };
+        assert_eq!(
+            vmm_action_from_request(
+                parse_patch_balloon(&Body::new(body), Some("statistics")).unwrap()
+            ),
+            VmmAction::UpdateBalloonStatistics(expected_config)
+        );
     }
 
     #[test]
@@ -153,17 +153,17 @@ mod tests {
 
         // PUT with invalid fields.
         let body = r#"{
-                "amount_mib": "bar",
-                "is_read_only": false
-              }"#;
+            "amount_mib": "bar",
+            "is_read_only": false
+        }"#;
         assert!(parse_put_balloon(&Body::new(body)).is_err());
 
         // PUT with valid input fields.
         let body = r#"{
-                "amount_mib": 1000,
-                "deflate_on_oom": true,
-                "stats_polling_interval_s": 0
-            }"#;
+            "amount_mib": 1000,
+            "deflate_on_oom": true,
+            "stats_polling_interval_s": 0
+        }"#;
         assert!(parse_put_balloon(&Body::new(body)).is_ok());
     }
 }

src/api_server/src/request/boot_source.rs

@@ -27,10 +27,10 @@ mod tests {
         assert!(parse_put_boot_source(&Body::new("invalid_payload")).is_err());
 
         let body = r#"{
-                "kernel_image_path": "/foo/bar",
-                "initrd_path": "/bar/foo",
-                "boot_args": "foobar"
-              }"#;
+            "kernel_image_path": "/foo/bar",
+            "initrd_path": "/bar/foo",
+            "boot_args": "foobar"
+        }"#;
         let same_body = BootSourceConfig {
             kernel_image_path: String::from("/foo/bar"),
             initrd_path: Some(String::from("/bar/foo")),

src/api_server/src/request/cpu_configuration.rs

@@ -40,18 +40,14 @@ mod tests {
         );
         let cpu_template_json = cpu_config_json_result.unwrap();
 
-        {
-            match vmm_action_from_request(
-                parse_put_cpu_config(&Body::new(cpu_template_json.as_bytes())).unwrap(),
-            ) {
-                VmmAction::PutCpuConfiguration(received_cpu_template) => {
-                    // Test that the CPU config to be used for KVM config is the
-                    // the same that was read in from a test file.
-                    assert_eq!(cpu_template, received_cpu_template);
-                }
-                _ => panic!("Test failed - Expected VmmAction::PutCpuConfiguration() call"),
-            }
-        }
+        // Test that the CPU config to be used for KVM config is the same that
+        // was read in from a test file.
+        assert_eq!(
+            vmm_action_from_request(
+                parse_put_cpu_config(&Body::new(cpu_template_json.as_bytes())).unwrap()
+            ),
+            VmmAction::PutCpuConfiguration(cpu_template)
+        );
 
         // Test empty request succeeds
         let parse_cpu_config_result = parse_put_cpu_config(&Body::new(r#"{ }"#));