qemu: lock guest memory for x86_64 guests on Intel

Configuration/UTMQemuConfiguration+Arguments.swift

@@ -551,6 +551,11 @@ import Virtualization // for getting network interfaces
         }
     }
 
+    /// Keeps guest RAM resident so the host does not compress or swap it.
+    private var isMemoryLockUsed: Bool {
+        system.architecture == .x86_64 && isHypervisorUsed && qemu.hasMemoryLock
+    }
+
     private var isTSOUsed: Bool {
         system.architecture.hasTSOSupport && qemu.hasTSO
     }
@@ -694,6 +699,10 @@ import Virtualization // for getting network interfaces
         f("-m")
         system.memorySize
         f()
+        if isMemoryLockUsed {
+            f("-overcommit")
+            f("mem-lock=on")
+        }
     }
 
     var hasCustomBios: Bool {

Configuration/UTMQemuConfigurationQEMU.swift

@@ -57,6 +57,8 @@ struct UTMQemuConfigurationQEMU: Codable {
 
     /// Add an interrupt remapping IOMMU for x86_64 q35 guests using the hypervisor on Intel.
     var hasInterruptRemapping: Bool = true
+    /// Lock guest RAM in host memory for x86_64 guests using the hypervisor on Intel.
+    var hasMemoryLock: Bool = true
 
     /// QEMU machine property that overrides the default property defined by UTM.
     var machinePropertyOverride: String?
@@ -96,6 +98,7 @@ struct UTMQemuConfigurationQEMU: Codable {
         case hasRTCLocalTime = "RTCLocalTime"
         case hasPS2Controller = "PS2Controller"
         case hasInterruptRemapping = "InterruptRemapping"
+        case hasMemoryLock = "MemoryLock"
         case machinePropertyOverride = "MachinePropertyOverride"
         case additionalArguments = "AdditionalArguments"
     }
@@ -115,6 +118,7 @@ struct UTMQemuConfigurationQEMU: Codable {
         hasRTCLocalTime = try values.decode(Bool.self, forKey: .hasRTCLocalTime)
         hasPS2Controller = try values.decode(Bool.self, forKey: .hasPS2Controller)
         hasInterruptRemapping = try values.decodeIfPresent(Bool.self, forKey: .hasInterruptRemapping) ?? true
+        hasMemoryLock = try values.decodeIfPresent(Bool.self, forKey: .hasMemoryLock) ?? true
         machinePropertyOverride = try values.decodeIfPresent(String.self, forKey: .machinePropertyOverride)
         additionalArguments = try values.decode([QEMUArgument].self, forKey: .additionalArguments)
         if let dataURL = decoder.userInfo[.dataURL] as? URL {
@@ -136,6 +140,7 @@ struct UTMQemuConfigurationQEMU: Codable {
         try container.encode(hasRTCLocalTime, forKey: .hasRTCLocalTime)
         try container.encode(hasPS2Controller, forKey: .hasPS2Controller)
         try container.encode(hasInterruptRemapping, forKey: .hasInterruptRemapping)
+        try container.encode(hasMemoryLock, forKey: .hasMemoryLock)
         try container.encodeIfPresent(machinePropertyOverride, forKey: .machinePropertyOverride)
         try container.encode(additionalArguments, forKey: .additionalArguments)
     }

Platform/Shared/VMConfigQEMUView.swift

@@ -67,6 +67,8 @@ struct VMConfigQEMUView: View {
                     if config.system.architecture == .x86_64 && config.qemu.hasHypervisor {
                         Toggle("Interrupt remapping", isOn: $config.qemu.hasInterruptRemapping)
                             .help("Lets the guest use faster interrupt handling, which reduces stutter and audio dropouts in Windows. Requires the Q35 machine.")
+                        Toggle("Lock guest memory", isOn: $config.qemu.hasMemoryLock)
+                            .help("Keeps the guest's memory resident so macOS does not compress or swap it. The Mac needs enough free memory for the whole guest.")
                     }
                     #endif
                     Toggle("Use local time for base clock", isOn: $config.qemu.hasRTCLocalTime)