Add VTimer as alternative interrupt method on Apple Hypervisor (#5663)

* Add VTimer as alternative interrupt method on Apple Hypervisor

* Fix naming violations on TimeApi

* Fix timer interval (was 16us rather than 16ms)

* Fix delta ticks calculation

* Missing ThrowOnError call

* Add SupportedOSPlatform attribute on AppleHv classes

src/Ryujinx.Cpu/AppleHv/HvVcpu.cs

@@ -1,7 +1,15 @@
+using System.Diagnostics;
+using System.Runtime.Versioning;
+
 namespace Ryujinx.Cpu.AppleHv
 {
+    [SupportedOSPlatform("macos")]
     unsafe class HvVcpu
     {
+        private const ulong InterruptIntervalNs = 16 * 1000000; // 16 ms
+
+        private static ulong _interruptTimeDeltaTicks = 0;
+
         public readonly ulong Handle;
         public readonly HvVcpuExit* ExitInfo;
         public readonly IHvExecutionContext ShadowContext;
@@ -21,5 +29,28 @@ namespace Ryujinx.Cpu.AppleHv
             NativeContext = nativeContext;
             IsEphemeral = isEphemeral;
         }
+
+        public void EnableAndUpdateVTimer()
+        {
+            // We need to ensure interrupts will be serviced,
+            // and for that we set up the VTime to trigger an interrupt at fixed intervals.
+
+            ulong deltaTicks = _interruptTimeDeltaTicks;
+
+            if (deltaTicks == 0)
+            {
+                // Calculate our time delta in ticks based on the current clock frequency.
+
+                int result = TimeApi.mach_timebase_info(out var timeBaseInfo);
+
+                Debug.Assert(result == 0);
+
+                deltaTicks = ((InterruptIntervalNs * timeBaseInfo.Denom) + (timeBaseInfo.Numer - 1)) / timeBaseInfo.Numer;
+                _interruptTimeDeltaTicks = deltaTicks;
+            }
+
+            HvApi.hv_vcpu_set_sys_reg(Handle, HvSysReg.CNTV_CTL_EL0, 1).ThrowOnError();
+            HvApi.hv_vcpu_set_sys_reg(Handle, HvSysReg.CNTV_CVAL_EL0, TimeApi.mach_absolute_time() + deltaTicks).ThrowOnError();
+        }
     }
 }