chore: Cleanup 4.14 related logic in hugepages feature

Hugepages wasn't supported on host kernel 4.14 due to memfd_create not
allowing the combination of MFD_HUGETLB and MFD_ALLOW_SEALING. Now that

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

src/vmm/src/resources.rs

@@ -501,7 +501,6 @@ mod tests {
     use std::str::FromStr;
 
     use serde_json::{Map, Value};
-    use utils::kernel_version::KernelVersion;
     use utils::net::mac::MacAddr;
     use utils::tempfile::TempFile;
 
@@ -1409,14 +1408,12 @@ mod tests {
             VmConfigError::InvalidMemorySize
         );
 
-        if KernelVersion::get().unwrap() >= KernelVersion::new(5, 10, 0) {
-            // mem_size_mib compatible with huge page configuration
-            aux_vm_config.mem_size_mib = Some(2048);
-            // Remove the balloon device config that's added by `default_vm_resources` as it would
-            // trigger the "ballooning incompatible with huge pages" check.
-            vm_resources.balloon = BalloonBuilder::new();
-            vm_resources.update_vm_config(&aux_vm_config).unwrap();
-        }
+        // mem_size_mib compatible with huge page configuration
+        aux_vm_config.mem_size_mib = Some(2048);
+        // Remove the balloon device config that's added by `default_vm_resources` as it would
+        // trigger the "ballooning incompatible with huge pages" check.
+        vm_resources.balloon = BalloonBuilder::new();
+        vm_resources.update_vm_config(&aux_vm_config).unwrap();
     }
 
     #[test]
@@ -1454,29 +1451,27 @@ mod tests {
 
     #[test]
     fn test_negative_restore_balloon_device_with_huge_pages() {
-        if KernelVersion::get().unwrap() >= KernelVersion::new(4, 16, 0) {
-            let mut vm_resources = default_vm_resources();
-            vm_resources.balloon = BalloonBuilder::new();
-            vm_resources
-                .update_vm_config(&MachineConfigUpdate {
-                    huge_pages: Some(HugePageConfig::Hugetlbfs2M),
-                    ..Default::default()
-                })
-                .unwrap();
-            let err = vm_resources
-                .update_from_restored_device(SharedDeviceType::Balloon(Arc::new(Mutex::new(
-                    Balloon::new(128, false, 0, true).unwrap(),
-                ))))
-                .unwrap_err();
-            assert!(
-                matches!(
-                    err,
-                    ResourcesError::BalloonDevice(BalloonConfigError::HugePages)
-                ),
-                "{:?}",
-                err
-            );
-        }
+        let mut vm_resources = default_vm_resources();
+        vm_resources.balloon = BalloonBuilder::new();
+        vm_resources
+            .update_vm_config(&MachineConfigUpdate {
+                huge_pages: Some(HugePageConfig::Hugetlbfs2M),
+                ..Default::default()
+            })
+            .unwrap();
+        let err = vm_resources
+            .update_from_restored_device(SharedDeviceType::Balloon(Arc::new(Mutex::new(
+                Balloon::new(128, false, 0, true).unwrap(),
+            ))))
+            .unwrap_err();
+        assert!(
+            matches!(
+                err,
+                ResourcesError::BalloonDevice(BalloonConfigError::HugePages)
+            ),
+            "{:?}",
+            err
+        );
     }
 
     #[test]

src/vmm/src/vmm_config/machine_config.rs

@@ -4,7 +4,6 @@ use std::fmt::Debug;
 
 use serde::{Deserialize, Serialize};
 use utils::kernel_version;
-use utils::kernel_version::KernelVersion;
 
 use crate::cpu_config::templates::{CpuTemplateType, CustomCpuTemplate, StaticCpuTemplate};
 
@@ -31,8 +30,6 @@ pub enum VmConfigError {
     SmtNotSupported,
     /// Could not determine host kernel version when checking hugetlbfs compatibility
     KernelVersion,
-    /// Firecracker's hugetlbfs support requires at least host kernel 5.10.
-    HugetlbfsNotSupported,
     /// Firecracker's huge pages support is incompatible with memory ballooning.
     BalloonAndHugePages,
     /// Firecracker's huge pages support is incompatible with initrds.
@@ -243,10 +240,6 @@ impl VmConfig {
             Some(other) => Some(CpuTemplateType::Static(other)),
         };
 
-        if page_config.is_hugetlbfs() && KernelVersion::get()? < KernelVersion::new(4, 16, 0) {
-            return Err(VmConfigError::HugetlbfsNotSupported);
-        }
-
         Ok(VmConfig {
             vcpu_count,
             mem_size_mib,
@@ -283,27 +276,3 @@ impl From<&VmConfig> for MachineConfig {
         }
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use utils::kernel_version::KernelVersion;
-
-    use crate::vmm_config::machine_config::{
-        HugePageConfig, MachineConfigUpdate, VmConfig, VmConfigError,
-    };
-
-    #[test]
-    fn test_hugetlbfs_not_supported_4_14() {
-        if KernelVersion::get().unwrap() < KernelVersion::new(4, 16, 0) {
-            let base_config = VmConfig::default();
-            let update = MachineConfigUpdate {
-                huge_pages: Some(HugePageConfig::Hugetlbfs2M),
-                mem_size_mib: Some(1024),
-                ..Default::default()
-            };
-
-            let err = base_config.update(&update).unwrap_err();
-            assert_eq!(err, VmConfigError::HugetlbfsNotSupported)
-        }
-    }
-}