kern/amd64: mp: Add multiprocessing groundwork

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 134 insertions, 0 deletions

diff --git a/sys/arch/amd64/cpu/mp.c b/sys/arch/amd64/cpu/mp.c
new file mode 100644
index 0000000..09c824e
--- /dev/null
+++ b/sys/arch/amd64/cpu/mp.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/cdefs.h>
+#include <acpi/acpi.h>
+#include <os/trace.h>
+#include <kern/panic.h>
+#include <dev/clkdev/hpet.h>
+#include <lib/string.h>
+#include <md/lapic.h>
+#include <mu/cpu.h>
+#include <vm/vm.h>
+
+#define dtrace(fmt, ...) trace("mp: " fmt, ##__VA_ARGS__)
+
+/*
+ * The startup code is copied to the processor bring up area
+ * to which it is executed in real mode. This area must fit
+ * within a page and be no larger and no smaller.
+ */
+#define AP_BUA_LEN   0x1000                     /* Bring up area length in bytes */
+#define AP_BUA_PADDR 0x1000                     /* Bring up area [physical] */
+#define AP_BUA_VADDR PHYS_TO_VIRT(AP_BUA_PADDR) /* Bring up area [virtual] */
+
+__section(".trampoline") static char ap_code[4096];
+
+static int
+cpu_lapic_cb(struct apic_header *h, size_t arg)
+{
+    struct local_apic *lapic;
+    struct cpu_info *self;
+    struct mcb *mcb;
+    struct lapic_ipi ipi;
+    int error;
+
+    self = cpu_self();
+    if (self == NULL) {
+        panic("mp: could not get self\n");
+    }
+
+    mcb = &self->mcb;
+
+    /* Skip ourselves */
+    lapic = (struct local_apic *)h;
+    if (lapic->apic_id == arg) {
+        return -1;
+    }
+
+    /* Prepare the IPI packet */
+    ipi.dest_id = lapic->apic_id;
+    ipi.vector = 0;
+    ipi.delmod = IPI_DELMOD_INIT;
+    ipi.shorthand = IPI_SHAND_NONE;
+    ipi.logical_dest = 0;
+    error = lapic_send_ipi(mcb, &ipi);
+    if (error < 0) {
+        panic("mp: failed to send INIT IPI\n");
+    }
+
+    /* Give it 20ms then prep a STARTUP */
+    hpet_msleep(20);
+    ipi.delmod = IPI_DELMOD_STARTUP;
+    ipi.vector = (AP_BUA_PADDR >> 12);
+
+    /* The MPSpec says to send two */
+    for (uint8_t i = 0; i < 2; ++i) {
+        error = lapic_send_ipi(mcb, &ipi);
+        if (error != 0) {
+            panic("mp: failed to send STARTUP IPI\n");
+        }
+        hpet_msleep(2);
+    }
+
+    dtrace("bootstrapping lapic %d\n", lapic->apic_id);
+    return -1;  /* Keep going */
+}
+
+void
+cpu_start_aps(struct cpu_info *ci)
+{
+    struct cpu_info *self;
+    struct mcb *mcb;
+    size_t bua_len;
+    uint8_t *bua;
+
+    if (ci == NULL) {
+        return;
+    }
+
+    self = cpu_self();
+    if (self == NULL) {
+        panic("mp: could not get current processor\n");
+    }
+
+    /* Copy the bring up code to the BUA */
+    bua = AP_BUA_VADDR;
+    memcpy(bua, ap_code, AP_BUA_LEN);
+
+    /* Start up the APs */
+    mcb = &self->mcb;
+    dtrace("bringing up application processors...\n");
+    acpi_read_madt(
+        APIC_TYPE_LOCAL_APIC,
+        cpu_lapic_cb,
+        lapic_read_id(mcb)
+    );
+}