1 files changed, 78 insertions, 0 deletions
diff --git a/arch/x86/kernel/apic/apic_noop.c b/arch/x86/kernel/apic/apic_noop.c
new file mode 100644
index 000000000..966d7cf10
--- /dev/null
+++ b/arch/x86/kernel/apic/apic_noop.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * NOOP APIC driver.
+ *
+ * Does almost nothing and should be substituted by a real apic driver via
+ * probe routine.
+ *
+ * Though in case if apic is disabled (for some reason) we try
+ * to not uglify the caller's code and allow to call (some) apic routines
+ * like self-ipi, etc...
+ *
+ * FIXME: Remove this gunk. The above argument which was intentionally left
+ * in place is silly to begin with because none of the callbacks except for
+ * APIC::read/write() have a WARN_ON_ONCE() in them. Sigh...
+ */
+#include <linux/cpumask.h>
+#include <linux/thread_info.h>
+
+#include <asm/apic.h>
+
+static void noop_send_IPI(int cpu, int vector) { }
+static void noop_send_IPI_mask(const struct cpumask *cpumask, int vector) { }
+static void noop_send_IPI_mask_allbutself(const struct cpumask *cpumask, int vector) { }
+static void noop_send_IPI_allbutself(int vector) { }
+static void noop_send_IPI_all(int vector) { }
+static void noop_send_IPI_self(int vector) { }
+static void noop_apic_icr_write(u32 low, u32 id) { }
+static int noop_wakeup_secondary_cpu(int apicid, unsigned long start_eip) { return -1; }
+static u64 noop_apic_icr_read(void) { return 0; }
+static int noop_phys_pkg_id(int cpuid_apic, int index_msb) { return 0; }
+static unsigned int noop_get_apic_id(unsigned long x) { return 0; }
+static void noop_apic_eoi(void) { }
+
+static u32 noop_apic_read(u32 reg)
+{
+	WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !apic_is_disabled);
+	return 0;
+}
+
+static void noop_apic_write(u32 reg, u32 val)
+{
+	WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_APIC) && !apic_is_disabled);
+}
+
+struct apic apic_noop __ro_after_init = {
+	.name				= "noop",
+
+	.delivery_mode			= APIC_DELIVERY_MODE_FIXED,
+	.dest_mode_logical		= true,
+
+	.disable_esr			= 0,
+
+	.check_apicid_used		= default_check_apicid_used,
+	.ioapic_phys_id_map		= default_ioapic_phys_id_map,
+	.cpu_present_to_apicid		= default_cpu_present_to_apicid,
+
+	.phys_pkg_id			= noop_phys_pkg_id,
+
+	.max_apic_id			= 0xFE,
+	.get_apic_id			= noop_get_apic_id,
+
+	.calc_dest_apicid		= apic_flat_calc_apicid,
+
+	.send_IPI			= noop_send_IPI,
+	.send_IPI_mask			= noop_send_IPI_mask,
+	.send_IPI_mask_allbutself	= noop_send_IPI_mask_allbutself,
+	.send_IPI_allbutself		= noop_send_IPI_allbutself,
+	.send_IPI_all			= noop_send_IPI_all,
+	.send_IPI_self			= noop_send_IPI_self,
+
+	.wakeup_secondary_cpu		= noop_wakeup_secondary_cpu,
+
+	.read				= noop_apic_read,
+	.write				= noop_apic_write,
+	.eoi				= noop_apic_eoi,
+	.icr_read			= noop_apic_icr_read,
+	.icr_write			= noop_apic_icr_write,
+};