1 files changed, 311 insertions, 0 deletions
diff --git a/arch/x86/kernel/apic/ipi.c b/arch/x86/kernel/apic/ipi.c
new file mode 100644
index 000000000..a44ba7209
--- /dev/null
+++ b/arch/x86/kernel/apic/ipi.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/cpumask.h>
+#include <linux/delay.h>
+#include <linux/smp.h>
+
+#include <asm/io_apic.h>
+
+#include "local.h"
+
+DEFINE_STATIC_KEY_FALSE(apic_use_ipi_shorthand);
+
+#ifdef CONFIG_SMP
+static int apic_ipi_shorthand_off __ro_after_init;
+
+static __init int apic_ipi_shorthand(char *str)
+{
+	get_option(&str, &apic_ipi_shorthand_off);
+	return 1;
+}
+__setup("no_ipi_broadcast=", apic_ipi_shorthand);
+
+static int __init print_ipi_mode(void)
+{
+	pr_info("IPI shorthand broadcast: %s\n",
+		apic_ipi_shorthand_off ? "disabled" : "enabled");
+	return 0;
+}
+late_initcall(print_ipi_mode);
+
+void apic_smt_update(void)
+{
+	/*
+	 * Do not switch to broadcast mode if:
+	 * - Disabled on the command line
+	 * - Only a single CPU is online
+	 * - Not all present CPUs have been at least booted once
+	 *
+	 * The latter is important as the local APIC might be in some
+	 * random state and a broadcast might cause havoc. That's
+	 * especially true for NMI broadcasting.
+	 */
+	if (apic_ipi_shorthand_off || num_online_cpus() == 1 ||
+	    !cpumask_equal(cpu_present_mask, &cpus_booted_once_mask)) {
+		static_branch_disable(&apic_use_ipi_shorthand);
+	} else {
+		static_branch_enable(&apic_use_ipi_shorthand);
+	}
+}
+
+void apic_send_IPI_allbutself(unsigned int vector)
+{
+	if (num_online_cpus() < 2)
+		return;
+
+	if (static_branch_likely(&apic_use_ipi_shorthand))
+		__apic_send_IPI_allbutself(vector);
+	else
+		__apic_send_IPI_mask_allbutself(cpu_online_mask, vector);
+}
+
+/*
+ * Send a 'reschedule' IPI to another CPU. It goes straight through and
+ * wastes no time serializing anything. Worst case is that we lose a
+ * reschedule ...
+ */
+void native_smp_send_reschedule(int cpu)
+{
+	if (unlikely(cpu_is_offline(cpu))) {
+		WARN(1, "sched: Unexpected reschedule of offline CPU#%d!\n", cpu);
+		return;
+	}
+	__apic_send_IPI(cpu, RESCHEDULE_VECTOR);
+}
+
+void native_send_call_func_single_ipi(int cpu)
+{
+	__apic_send_IPI(cpu, CALL_FUNCTION_SINGLE_VECTOR);
+}
+
+void native_send_call_func_ipi(const struct cpumask *mask)
+{
+	if (static_branch_likely(&apic_use_ipi_shorthand)) {
+		unsigned int cpu = smp_processor_id();
+
+		if (!cpumask_or_equal(mask, cpumask_of(cpu), cpu_online_mask))
+			goto sendmask;
+
+		if (cpumask_test_cpu(cpu, mask))
+			__apic_send_IPI_all(CALL_FUNCTION_VECTOR);
+		else if (num_online_cpus() > 1)
+			__apic_send_IPI_allbutself(CALL_FUNCTION_VECTOR);
+		return;
+	}
+
+sendmask:
+	__apic_send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
+}
+
+#endif /* CONFIG_SMP */
+
+static inline int __prepare_ICR2(unsigned int mask)
+{
+	return SET_XAPIC_DEST_FIELD(mask);
+}
+
+u32 apic_mem_wait_icr_idle_timeout(void)
+{
+	int cnt;
+
+	for (cnt = 0; cnt < 1000; cnt++) {
+		if (!(apic_read(APIC_ICR) & APIC_ICR_BUSY))
+			return 0;
+		inc_irq_stat(icr_read_retry_count);
+		udelay(100);
+	}
+	return APIC_ICR_BUSY;
+}
+
+void apic_mem_wait_icr_idle(void)
+{
+	while (native_apic_mem_read(APIC_ICR) & APIC_ICR_BUSY)
+		cpu_relax();
+}
+
+/*
+ * This is safe against interruption because it only writes the lower 32
+ * bits of the APIC_ICR register. The destination field is ignored for
+ * short hand IPIs.
+ *
+ *  wait_icr_idle()
+ *  write(ICR2, dest)
+ *  NMI
+ *	wait_icr_idle()
+ *	write(ICR)
+ *	wait_icr_idle()
+ *  write(ICR)
+ *
+ * This function does not need to disable interrupts as there is no ICR2
+ * interaction. The memory write is direct except when the machine is
+ * affected by the 11AP Pentium erratum, which turns the plain write into
+ * an XCHG operation.
+ */
+static void __default_send_IPI_shortcut(unsigned int shortcut, int vector)
+{
+	/*
+	 * Wait for the previous ICR command to complete.  Use
+	 * safe_apic_wait_icr_idle() for the NMI vector as there have been
+	 * issues where otherwise the system hangs when the panic CPU tries
+	 * to stop the others before launching the kdump kernel.
+	 */
+	if (unlikely(vector == NMI_VECTOR))
+		apic_mem_wait_icr_idle_timeout();
+	else
+		apic_mem_wait_icr_idle();
+
+	/* Destination field (ICR2) and the destination mode are ignored */
+	native_apic_mem_write(APIC_ICR, __prepare_ICR(shortcut, vector, 0));
+}
+
+/*
+ * This is used to send an IPI with no shorthand notation (the destination is
+ * specified in bits 56 to 63 of the ICR).
+ */
+void __default_send_IPI_dest_field(unsigned int dest_mask, int vector,
+				   unsigned int dest_mode)
+{
+	/* See comment in __default_send_IPI_shortcut() */
+	if (unlikely(vector == NMI_VECTOR))
+		apic_mem_wait_icr_idle_timeout();
+	else
+		apic_mem_wait_icr_idle();
+
+	/* Set the IPI destination field in the ICR */
+	native_apic_mem_write(APIC_ICR2, __prepare_ICR2(dest_mask));
+	/* Send it with the proper destination mode */
+	native_apic_mem_write(APIC_ICR, __prepare_ICR(0, vector, dest_mode));
+}
+
+void default_send_IPI_single_phys(int cpu, int vector)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	__default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid, cpu),
+				      vector, APIC_DEST_PHYSICAL);
+	local_irq_restore(flags);
+}
+
+void default_send_IPI_mask_sequence_phys(const struct cpumask *mask, int vector)
+{
+	unsigned long flags;
+	unsigned long cpu;
+
+	local_irq_save(flags);
+	for_each_cpu(cpu, mask) {
+		__default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid,
+				cpu), vector, APIC_DEST_PHYSICAL);
+	}
+	local_irq_restore(flags);
+}
+
+void default_send_IPI_mask_allbutself_phys(const struct cpumask *mask,
+						 int vector)
+{
+	unsigned int cpu, this_cpu = smp_processor_id();
+	unsigned long flags;
+
+	local_irq_save(flags);
+	for_each_cpu(cpu, mask) {
+		if (cpu == this_cpu)
+			continue;
+		__default_send_IPI_dest_field(per_cpu(x86_cpu_to_apicid,
+				 cpu), vector, APIC_DEST_PHYSICAL);
+	}
+	local_irq_restore(flags);
+}
+
+/*
+ * Helper function for APICs which insist on cpumasks
+ */
+void default_send_IPI_single(int cpu, int vector)
+{
+	__apic_send_IPI_mask(cpumask_of(cpu), vector);
+}
+
+void default_send_IPI_allbutself(int vector)
+{
+	__default_send_IPI_shortcut(APIC_DEST_ALLBUT, vector);
+}
+
+void default_send_IPI_all(int vector)
+{
+	__default_send_IPI_shortcut(APIC_DEST_ALLINC, vector);
+}
+
+void default_send_IPI_self(int vector)
+{
+	__default_send_IPI_shortcut(APIC_DEST_SELF, vector);
+}
+
+#ifdef CONFIG_X86_32
+void default_send_IPI_mask_sequence_logical(const struct cpumask *mask, int vector)
+{
+	unsigned long flags;
+	unsigned int cpu;
+
+	local_irq_save(flags);
+	for_each_cpu(cpu, mask)
+		__default_send_IPI_dest_field(1U << cpu, vector, APIC_DEST_LOGICAL);
+	local_irq_restore(flags);
+}
+
+void default_send_IPI_mask_allbutself_logical(const struct cpumask *mask,
+						 int vector)
+{
+	unsigned int cpu, this_cpu = smp_processor_id();
+	unsigned long flags;
+
+	local_irq_save(flags);
+	for_each_cpu(cpu, mask) {
+		if (cpu == this_cpu)
+			continue;
+		__default_send_IPI_dest_field(1U << cpu, vector, APIC_DEST_LOGICAL);
+	}
+	local_irq_restore(flags);
+}
+
+void default_send_IPI_mask_logical(const struct cpumask *cpumask, int vector)
+{
+	unsigned long mask = cpumask_bits(cpumask)[0];
+	unsigned long flags;
+
+	if (!mask)
+		return;
+
+	local_irq_save(flags);
+	WARN_ON(mask & ~cpumask_bits(cpu_online_mask)[0]);
+	__default_send_IPI_dest_field(mask, vector, APIC_DEST_LOGICAL);
+	local_irq_restore(flags);
+}
+
+#ifdef CONFIG_SMP
+static int convert_apicid_to_cpu(int apic_id)
+{
+	int i;
+
+	for_each_possible_cpu(i) {
+		if (per_cpu(x86_cpu_to_apicid, i) == apic_id)
+			return i;
+	}
+	return -1;
+}
+
+int safe_smp_processor_id(void)
+{
+	int apicid, cpuid;
+
+	if (!boot_cpu_has(X86_FEATURE_APIC))
+		return 0;
+
+	apicid = read_apic_id();
+	if (apicid == BAD_APICID)
+		return 0;
+
+	cpuid = convert_apicid_to_cpu(apicid);
+
+	return cpuid >= 0 ? cpuid : 0;
+}
+#endif
+#endif