From 58deafb1d845d0e5cdbf8d139fca8ed1ecc4ab34 Mon Sep 17 00:00:00 2001
From: Aiken Harris <harraiken91@gmail.com>
Date: Mon, 27 Apr 2026 22:11:30 +0200
Subject: [PATCH] Add support for sending broadcast IPIs

---
 xtoskrnl/hl/x86/pic.cc      | 65 ++++++++++++++++++++++++++++++++++++-
 xtoskrnl/includes/hl/pic.hh |  8 +++--
 2 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/xtoskrnl/hl/x86/pic.cc b/xtoskrnl/hl/x86/pic.cc
index 2b82955..b7005fb 100644
--- a/xtoskrnl/hl/x86/pic.cc
+++ b/xtoskrnl/hl/x86/pic.cc
@@ -726,6 +726,69 @@ HL::Pic::ResolveInterruptOverride(IN UCHAR Irq,
     *Gsi = (ULONG)Irq;
 }
 
+/**
+ * Sends a Broadcast IPI (Inter-Processor Interrupt) to all processors in the system.
+ *
+ * @param Vector
+ *        Supplies the hardware interrupt vector to trigger on the target processors.
+ *
+ * @param Self
+ *        Supplies a boolean value indicating the broadcast scope.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+HL::Pic::SendBroadcastIpi(IN ULONG Vector,
+                          IN BOOLEAN Self)
+{
+    APIC_COMMAND_REGISTER Register;
+    BOOLEAN Interrupts;
+
+    /* Check whether interrupts are enabled */
+    Interrupts = AR::CpuFunc::InterruptsEnabled();
+
+    /* Disable interrupts */
+    AR::CpuFunc::ClearInterruptFlag();
+
+    /* Prepare the APIC command register */
+    Register.LongLong = 0;
+    Register.DeliveryMode = APIC_DM_FIXED;
+    Register.DestinationShortHand = Self ? APIC_DSH_AllIncludingSelf : APIC_DSH_AllExclusingSelf;
+    Register.Level = 1;
+    Register.TriggerMode = APIC_TGM_EDGE;
+    Register.Vector = Vector;
+
+    /* Check current APIC mode */
+    if(ApicMode == APIC_MODE_X2APIC)
+    {
+        /* In x2APIC mode, writing the full 64-bit value to the ICR MSR is sufficient */
+        WriteApicRegister(APIC_ICR0, Register.LongLong);
+    }
+    else
+    {
+        /* Wait for the APIC to clear the delivery status */
+        while((ReadApicRegister(APIC_ICR0) & 0x1000) != 0)
+        {
+            /* Yield the processor */
+            AR::CpuFunc::YieldProcessor();
+        }
+
+        /* In xAPIC compatibility mode, write the command to the ICR registers */
+        WriteApicRegister(APIC_ICR1, Register.Long1);
+        WriteApicRegister(APIC_ICR0, Register.Long0);
+    }
+
+    /* Check whether interrupts need to be re-enabled */
+    if(Interrupts)
+    {
+        /* Re-enable interrupts */
+        AR::CpuFunc::SetInterruptFlag();
+    }
+}
+
 /**
  * Signals to the APIC that handling an interrupt is complete.
  *
@@ -818,7 +881,7 @@ HL::Pic::SendSelfIpi(IN ULONG Vector)
             AR::CpuFunc::YieldProcessor();
         }
 
-        /* In xAPIC compatibility mode, ICR0 is used */
+        /* In xAPIC compatibility mode, write the command to the ICR registers */
         WriteApicRegister(APIC_ICR1, Register.Long1);
         WriteApicRegister(APIC_ICR0, Register.Long0);
 
diff --git a/xtoskrnl/includes/hl/pic.hh b/xtoskrnl/includes/hl/pic.hh
index da6578a..19c41d4 100644
--- a/xtoskrnl/includes/hl/pic.hh
+++ b/xtoskrnl/includes/hl/pic.hh
@@ -26,11 +26,16 @@ namespace HL
             STATIC UCHAR MappedVectors[256];
 
         public:
+            STATIC XTAPI VOID AllocateSystemInterrupt(IN UCHAR Irq,
+                                                      IN UCHAR RunLevel,
+                                                      IN UCHAR Vector);
             STATIC XTAPI VOID ClearApicErrors(VOID);
             STATIC XTAPI ULONG GetCpuApicId(VOID);
             STATIC XTAPI VOID InitializeIOApic(VOID);
             STATIC XTAPI VOID InitializePic(VOID);
             STATIC XTFASTCALL ULONGLONG ReadApicRegister(IN APIC_REGISTER Register);
+            STATIC XTAPI VOID SendBroadcastIpi(IN ULONG Vector,
+                                               IN BOOLEAN Self);
             STATIC XTAPI VOID SendEoi(VOID);
             STATIC XTAPI VOID SendIpi(IN ULONG ApicId,
                                       IN ULONG Vector);
@@ -39,9 +44,6 @@ namespace HL
                                                      IN ULONGLONG Value);
 
         private:
-            STATIC XTAPI VOID AllocateSystemInterrupt(IN UCHAR Irq,
-                                                      IN UCHAR RunLevel,
-                                                      IN UCHAR Vector);
             STATIC XTAPI BOOLEAN CheckApicSupport(VOID);
             STATIC XTAPI BOOLEAN CheckX2ApicSupport(VOID);
             STATIC XTAPI XTSTATUS DetectIoApicControllers(VOID);