refactor memory alignment to VZVirtualMachineInstance (#725)

Move the MiB rounding from LinuxContainer into
`VZVirtualMachineInstance`, so all callers are covered in one place and
the alignment constraint stays with the VMM layer that owns it.

This will also ensure LinuxPod can get memory alignment for free.

Author: yibozhuang

Sources/Containerization/LinuxContainer.swift

@@ -551,8 +551,7 @@ extension LinuxContainer {
             var modifiedRootfs = self.rootfs
             modifiedRootfs.options.removeAll(where: { $0 == "ro" })
 
-            let mib: UInt64 = 1.mib()
-            let vmMemory = (self.memoryInBytes + self.config.memoryOverhead + mib - 1) & ~(mib - 1)
+            let vmMemory = self.memoryInBytes + self.config.memoryOverhead
 
             let vmCpus = self.cpus + self.config.cpuOverhead
 

Sources/Containerization/VZVirtualMachineInstance.swift

@@ -315,7 +315,8 @@ extension VZVirtualMachineInstance.Configuration {
         var config = VZVirtualMachineConfiguration()
 
         config.cpuCount = self.cpus
-        config.memorySize = self.memoryInBytes
+        let mib: UInt64 = 1 << 20
+        config.memorySize = (self.memoryInBytes + mib - 1) & ~(mib - 1)
         config.entropyDevices = [VZVirtioEntropyDeviceConfiguration()]
         config.socketDevices = [VZVirtioSocketDeviceConfiguration()]
 

Sources/Integration/ContainerTests.swift

@@ -33,6 +33,7 @@ extension IntegrationSuite {
         let bs = try await bootstrap(id)
         let container = try LinuxContainer(id, rootfs: bs.rootfs, vmm: bs.vmm) { config in
             config.process.arguments = ["/bin/true"]
+            config.memoryInBytes = 250_000_000
             config.bootLog = bs.bootLog
         }
 

Sources/Integration/PodTests.swift

@@ -495,7 +495,7 @@ extension IntegrationSuite {
         let bs = try await bootstrap(id)
         let pod = try LinuxPod(id, vmm: bs.vmm) { config in
             config.cpus = 4
-            config.memoryInBytes = 1024.mib()
+            config.memoryInBytes = 1_000_000_000
             config.bootLog = bs.bootLog
         }