IPI TLB shootdowns

core/mem/shootdown.c

@@ -0,0 +1,47 @@
+#include <zinnia/atomic.h>
+#include <zinnia/irq.h>
+#include <zinnia/percpu.h>
+#include <zinnia/pmap.h>
+#include <arch/cpu.h>
+
+[[__percpu]]
+static atomic_size_t shootdown_req;
+
+[[__percpu]]
+static atomic_size_t shootdown_ack;
+
+void pmap_shootdown_handle() {
+    const size_t req = atomic_load(percpu_ref(shootdown_req), ATOMIC_ACQUIRE);
+    if (atomic_load(percpu_ref(shootdown_ack), ATOMIC_RELAXED) == req)
+        return;
+    pte_flush_all();
+    atomic_store(percpu_ref(shootdown_ack), req, ATOMIC_RELEASE);
+}
+
+void pmap_shootdown(struct pmap* pt) {
+    const size_t count = percpu_count();
+    if (count < 2)
+        return;
+
+    irq_lock();
+    struct percpu* self = percpu_get();
+    for (size_t i = 0; i < count; i++) {
+        struct percpu* cpu = percpu_cpu(i);
+        if (cpu == self || !cpu->online)
+            continue;
+        atomic_fetch_add(percpu_ref_on(cpu, shootdown_req), 1, ATOMIC_RELEASE);
+        pte_shootdown_kick(cpu);
+    }
+
+    for (size_t i = 0; i < count; i++) {
+        struct percpu* cpu = percpu_cpu(i);
+        if (cpu == self || !cpu->online)
+            continue;
+        const size_t req = atomic_load(percpu_ref_on(cpu, shootdown_req), ATOMIC_RELAXED);
+        while ((ptrdiff_t)(req - atomic_load(percpu_ref_on(cpu, shootdown_ack), ATOMIC_ACQUIRE)) > 0) {
+            pmap_shootdown_handle();
+            arch_cpu_pause();
+        }
+    }
+    irq_unlock();
+}