From 8d3b4ff95a63a51eb9b63e7e002e9294669247d5 Mon Sep 17 00:00:00 2001
From: Aiken Harris <harraiken91@gmail.com>
Date: Wed, 31 Jul 2024 21:16:39 +0200
Subject: [PATCH] Start application processors

---
 xtoskrnl/hl/init.c      |  3 ++
 xtoskrnl/hl/x86/cpu.c   | 80 +++++++++++++++++++++++++++++++++++++++++
 xtoskrnl/includes/hli.h |  9 +++++
 3 files changed, 92 insertions(+)

diff --git a/xtoskrnl/hl/init.c b/xtoskrnl/hl/init.c
index 6119f9a..6d526c3 100644
--- a/xtoskrnl/hl/init.c
+++ b/xtoskrnl/hl/init.c
@@ -36,6 +36,9 @@ HlInitializeSystem(VOID)
         return Status;
     }
 
+    /* Start all application processors */
+    HlStartAllProcessors();
+
     /* Return success */
     return STATUS_SUCCESS;
 }
diff --git a/xtoskrnl/hl/x86/cpu.c b/xtoskrnl/hl/x86/cpu.c
index b585ca6..4bec2db 100644
--- a/xtoskrnl/hl/x86/cpu.c
+++ b/xtoskrnl/hl/x86/cpu.c
@@ -78,3 +78,83 @@ HlStartProcessor(IN ULONG CpuId,
     /* Return success */
     return STATUS_SUCCESS;
 }
+
+XTAPI
+XTSTATUS
+HlStartAllProcessors(VOID)
+{
+    PHYSICAL_ADDRESS ApPhysicalAddress;
+    PVOID ApVirtualAddress;
+    BOOLEAN Interrupts;
+    XTSTATUS Status;
+    USHORT Cpu;
+
+/* Temp bootstrap code size */
+#define AP_SPINUP_PAGE_COUNT 5
+
+    /* Check if at least one AP is present */
+    if(HlpSystemInfo.CpuCount > 1)
+    {
+        /* Allocate 5 pages for AP bootstrap code and ensure it is low memory */
+        Status = MmAllocateHardwareMemory(AP_SPINUP_PAGE_COUNT, FALSE, &ApPhysicalAddress);
+        if(Status != STATUS_SUCCESS || ApPhysicalAddress.QuadPart > (0x100000 - AP_SPINUP_PAGE_COUNT * MM_PAGE_SIZE))
+        {
+            /* Not enough free pages at low memory available, return error */
+            return STATUS_INSUFFICIENT_RESOURCES;
+        }
+
+        /* Map AP bootstrap code */
+        Status = MmMapHardwareMemory(ApPhysicalAddress, AP_SPINUP_PAGE_COUNT, TRUE, &ApVirtualAddress);
+        if(Status != STATUS_SUCCESS)
+        {
+            /* Failed to map AP bootstrap code, return error */
+            return STATUS_INSUFFICIENT_RESOURCES;
+        }
+
+        /* Copy AP bootstrap code into low memory */
+        RtlCopyMemory(ApVirtualAddress, &ArStartApplicationProcessor, AP_SPINUP_PAGE_COUNT * MM_PAGE_SIZE);
+
+        /* Iterate over all CPUs and start them */
+        for(Cpu = 0; Cpu < HlpSystemInfo.CpuCount; Cpu++)
+        {
+            /* Check if this CPU is the BSP */
+            if(HlpSystemInfo.CpuInfo[Cpu].ApicId == HlpGetCpuApicId())
+            {
+                /* This is the BSP, set proper flag and mark as started */
+                HlpSystemInfo.CpuInfo[Cpu].Bsp = TRUE;
+                HlpSystemInfo.CpuInfo[Cpu].Started = TRUE;
+
+                /* Continue with next CPU */
+                continue;
+            }
+
+            /* Temp debugging */
+            DebugPrint(L"Starting CPU #%lu (ACPI ID: %u, APIC ID: %u)\n", Cpu, HlpSystemInfo.CpuInfo[Cpu].AcpiId, HlpSystemInfo.CpuInfo[Cpu].ApicId);
+
+            /* Check if interrupts are enabled and disable them */
+            Interrupts = ArInterruptsEnabled();
+            ArClearInterruptFlag();
+
+            /* Start the AP */
+            Status = HlStartProcessor(HlpSystemInfo.CpuInfo[Cpu].ApicId, ApPhysicalAddress);
+            if(Status == STATUS_SUCCESS)
+            {
+                /* Mark AP as started */
+                HlpSystemInfo.CpuInfo[Cpu].Started = TRUE;
+            }
+
+            /* Check if interrupts were originally enabled */
+            if(Interrupts)
+            {
+                /* Re-enable interrupts */
+                ArSetInterruptFlag();
+            }
+        }
+
+        /* Unmap AP bootstrap code */
+        MmUnmapHardwareMemory(ApVirtualAddress, AP_SPINUP_PAGE_COUNT, TRUE);
+    }
+
+    /* Return success */
+    return STATUS_SUCCESS;
+}
diff --git a/xtoskrnl/includes/hli.h b/xtoskrnl/includes/hli.h
index b32c9a3..bca7e06 100644
--- a/xtoskrnl/includes/hli.h
+++ b/xtoskrnl/includes/hli.h
@@ -82,6 +82,15 @@ XTFASTCALL
 VOID
 HlSetRunLevel(IN KRUNLEVEL RunLevel);
 
+XTAPI
+XTSTATUS
+HlStartAllProcessors(VOID);
+
+XTAPI
+XTSTATUS
+HlStartProcessor(IN ULONG CpuId,
+                 IN PHYSICAL_ADDRESS ApEntryPoint);
+
 XTAPI
 VOID
 HlpCacheAcpiTable(IN PACPI_DESCRIPTION_HEADER AcpiTable);