From 7205dd7463dbef7c9f9390aa2da4e55e4d3eac14 Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Tue, 12 Apr 2022 20:17:27 -0600
Subject: [PATCH] Unmap xAPIC page if already mapped

---
 src/arch/x86_64/device/local_apic.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/arch/x86_64/device/local_apic.rs b/src/arch/x86_64/device/local_apic.rs
index ab2c784..913781e 100644
--- a/src/arch/x86_64/device/local_apic.rs
+++ b/src/arch/x86_64/device/local_apic.rs
@@ -48,8 +48,16 @@ impl LocalApic {
         if ! self.x2 {
             let page = Page::containing_address(VirtualAddress::new(self.address));
             let frame = Frame::containing_address(PhysicalAddress::new(self.address - crate::PHYS_OFFSET));
+            log::info!("Detected xAPIC at {:#x}", frame.start_address().data());
+            if active_table.translate_page(page).is_some() {
+                // Unmap xAPIC page if already mapped
+                let (result, _frame) = active_table.unmap_return(page, true);
+                result.flush();
+            }
             let result = active_table.map_to(page, frame, PageFlags::new().write(true));
             result.flush();
+        } else {
+            log::info!("Detected x2APIC");
         }
 
         self.init_ap();