From 5a9df7ca86474267384fc1a70976fc12e58a26ee Mon Sep 17 00:00:00 2001
From: Aiken Harris <harraiken91@gmail.com>
Date: Wed, 10 Jun 2026 11:13:28 +0200
Subject: [PATCH] Add helper to set full system processor affinity mask

---
 xtoskrnl/includes/ke/affinity.hh |  1 +
 xtoskrnl/ke/affinity.cc          | 43 ++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/xtoskrnl/includes/ke/affinity.hh b/xtoskrnl/includes/ke/affinity.hh
index 22b3844..44af10a 100644
--- a/xtoskrnl/includes/ke/affinity.hh
+++ b/xtoskrnl/includes/ke/affinity.hh
@@ -37,6 +37,7 @@ namespace KE
                                                         IN PKAFFINITY_MAP AffinityMap);
             STATIC XTAPI ULONG FindNextRightSetProcessor(IN ULONG ThreadSeed,
                                                          IN PKAFFINITY_MAP AffinityMap);
+            STATIC XTFASTCALL VOID SetAllProcessorsAffinity(IN OUT PKAFFINITY_MAP AffinityMap);
             STATIC XTFASTCALL VOID SetProcessorAffinity(IN OUT PKAFFINITY_MAP AffinityMap,
                                                         IN ULONG CpuNumber);
     };
diff --git a/xtoskrnl/ke/affinity.cc b/xtoskrnl/ke/affinity.cc
index 956ccd5..2d13335 100644
--- a/xtoskrnl/ke/affinity.cc
+++ b/xtoskrnl/ke/affinity.cc
@@ -404,6 +404,49 @@ KE::Affinity::FindNextRightSetProcessor(IN ULONG ThreadSeed,
     return 0;
 }
 
+/**
+ * Populates the affinity map with all available processors.
+ *
+ * @param AffinityMap
+ *        Supplies a pointer to the affinity map to be fully populated.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTFASTCALL
+VOID
+KE::Affinity::SetAllProcessorsAffinity(IN OUT PKAFFINITY_MAP AffinityMap)
+{
+    ULONG Cpus, Index;
+
+    /* Get the number of available CPUs */
+    Cpus = KE::Processor::GetInstalledCpus();
+
+    /* Iterate through all allocated blocks in the map */
+    for(Index = 0; Index < AffinityMap->Size; Index++)
+    {
+        /* Evaluate if the remaining logical processors fully saturate the current block */
+        if(Cpus >= 64)
+        {
+            /* Set all 64 bits and decrement the remaining count */
+            AffinityMap->Bitmap[Index] = ~((KAFFINITY)0);
+            Cpus -= 64;
+        }
+        else if(Cpus > 0)
+        {
+            /* Generate a partial bitmask for the tail end of the processors */
+            AffinityMap->Bitmap[Index] = (((KAFFINITY)1 << Cpus) - 1);
+            Cpus = 0;
+        }
+        else
+        {
+            /* Ensure any remaining blocks are safely zeroed */
+            AffinityMap->Bitmap[Index] = 0;
+        }
+    }
+}
+
 /**
  * Sets the affinity bit for a specified processor. This is a non-atomic operation.
  *