WIP x86 SMP

arch/x86/mp.c

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2024 Travis Geiselbrecht
+ *
+ * Use of this source code is governed by a MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT
+ */
+#include <arch/x86/mp.h>
+
+#include <assert.h>
+#include <arch/x86.h>
+#include <sys/types.h>
+
+// the boot cpu's percpu struct
+static x86_percpu_t x86_boot_percpu;
+// pointer to an array of percpu structs for each of the secondary cpus
+static x86_percpu_t **x86_ap_percpus;
+
+static x86_percpu_t *percpu_for_cpu(uint cpu_num) {
+    DEBUG_ASSERT(cpu_num < SMP_MAX_CPUS);
+    if (cpu_num == 0) {
+        return &x86_boot_percpu;
+    }
+    DEBUG_ASSERT(x86_ap_percpus);
+    return x86_ap_percpus[cpu_num - 1];
+}
+
+void x86_percpu_init_early(uint cpu_num, uint apic_id) {
+    x86_percpu_t *percpu = percpu_for_cpu(cpu_num);
+
+    percpu->self = percpu;
+    percpu->cpu_num = cpu_num;
+    percpu->apic_id = apic_id;
+
+    // XXX load into gs:/fs/etc
+#if ARCH_X86_64
+    write_msr(X86_MSR_IA32_KERNEL_GS_BASE, 0);
+    write_msr(X86_MSR_IA32_GS_BASE, (uint64_t)percpu);
+#else
+//#error implement
+#endif
+}