From 6b20f1fb19eaf881cdc021a64015357b07de9f53 Mon Sep 17 00:00:00 2001
From: "Justin C. Miller" <justin@devjustinian.com>
Date: Tue, 4 Oct 2022 20:10:41 -0700
Subject: [PATCH] [kernel] Make sure high bits are 0 writing SFMASK MSR

QEMU handles bits bring written in the (reserved) high bits of SFMASK
just fine, but KVM gives a #GP exception.
---
 src/kernel/syscall.s | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/kernel/syscall.s b/src/kernel/syscall.s
index ad41c2d..69a4253 100644
--- a/src/kernel/syscall.s
+++ b/src/kernel/syscall.s
@@ -116,6 +116,7 @@ syscall_enable:
 
 	mov rcx, MSR_FMASK
 	mov rax, FMASK_VAL
+	mov rdx, 0
 	wrmsr
 
 	pop rbp