acrn: support mwait emulation

As we can only emulate unmonitored mwait, some adjust have to be made for kernel idle routing when running as ACRN guest. 1. Mark ecx bit2 for mwait to indicate an unmonitored mwait. 2. Clear TIF_POLLING_NRFLAG so that kernel uses event to wakeup core. Signed-off-by: Wu Zhou <[email protected]>
projectceladon · Nov 21, 2024 · ca78549 · ca78549
1 parent d427fd8
commit ca78549
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
@@ -7,6 +7,7 @@
 
 #include <asm/cpufeature.h>
 #include <asm/nospec-branch.h>
+#include <asm/hypervisor.h>
 
 #define MWAIT_SUBSTATE_MASK		0xf
 #define MWAIT_CSTATE_MASK		0xf
@@ -115,8 +116,13 @@ static inline void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
 		}
 
 		__monitor((void *)&current_thread_info()->flags, 0, 0);
-		if (!need_resched())
+		if (!need_resched()) {
+			if (hypervisor_is_type(X86_HYPER_ACRN)) {
+				current_clr_polling();
+				ecx |= 0x4;
+			}
 			__mwait(eax, ecx);
+		}
 	}
 	current_clr_polling();
 }