MIPS: Add code for new system 'paravirt'

For para-virtualized guests running under KVM or other equivalent
hypervisor.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: James Hogan <james.hogan@imgtec.com>
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7004/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 148 insertions, 0 deletions

diff --git a/arch/mips/paravirt/paravirt-smp.c b/arch/mips/paravirt/paravirt-smp.c
new file mode 100644
index 000000000000..73a123e08c28
--- /dev/null
+++ b/arch/mips/paravirt/paravirt-smp.c
@@ -0,0 +1,148 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2013 Cavium, Inc.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/cpumask.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+
+#include <asm/mipsregs.h>
+#include <asm/setup.h>
+#include <asm/time.h>
+#include <asm/smp.h>
+
+/*
+ * Writing the sp releases the CPU, so writes must be ordered, gp
+ * first, then sp.
+ */
+unsigned long paravirt_smp_sp[NR_CPUS];
+unsigned long paravirt_smp_gp[NR_CPUS];
+
+static int numcpus = 1;
+
+static int __init set_numcpus(char *str)
+{
+	int newval;
+
+	if (get_option(&str, &newval)) {
+		if (newval < 1 || newval >= NR_CPUS)
+			goto bad;
+		numcpus = newval;
+		return 0;
+	}
+bad:
+	return -EINVAL;
+}
+early_param("numcpus", set_numcpus);
+
+
+static void paravirt_smp_setup(void)
+{
+	int id;
+	unsigned int cpunum = get_ebase_cpunum();
+
+	if (WARN_ON(cpunum >= NR_CPUS))
+		return;
+
+	/* The present CPUs are initially just the boot cpu (CPU 0). */
+	for (id = 0; id < NR_CPUS; id++) {
+		set_cpu_possible(id, id == 0);
+		set_cpu_present(id, id == 0);
+	}
+	__cpu_number_map[cpunum] = 0;
+	__cpu_logical_map[0] = cpunum;
+
+	for (id = 0; id < numcpus; id++) {
+		set_cpu_possible(id, true);
+		set_cpu_present(id, true);
+		__cpu_number_map[id] = id;
+		__cpu_logical_map[id] = id;
+	}
+}
+
+void irq_mbox_ipi(int cpu, unsigned int actions);
+static void paravirt_send_ipi_single(int cpu, unsigned int action)
+{
+	irq_mbox_ipi(cpu, action);
+}
+
+static void paravirt_send_ipi_mask(const struct cpumask *mask, unsigned int action)
+{
+	unsigned int cpu;
+
+	for_each_cpu_mask(cpu, *mask)
+		paravirt_send_ipi_single(cpu, action);
+}
+
+static void paravirt_init_secondary(void)
+{
+	unsigned int sr;
+
+	sr = set_c0_status(ST0_BEV);
+	write_c0_ebase((u32)ebase);
+
+	sr |= STATUSF_IP2; /* Interrupt controller on IP2 */
+	write_c0_status(sr);
+
+	irq_cpu_online();
+}
+
+static void paravirt_smp_finish(void)
+{
+	/* to generate the first CPU timer interrupt */
+	write_c0_compare(read_c0_count() + mips_hpt_frequency / HZ);
+	local_irq_enable();
+}
+
+static void paravirt_cpus_done(void)
+{
+}
+
+static void paravirt_boot_secondary(int cpu, struct task_struct *idle)
+{
+	paravirt_smp_gp[cpu] = (unsigned long)task_thread_info(idle);
+	smp_wmb();
+	paravirt_smp_sp[cpu] = __KSTK_TOS(idle);
+}
+
+static irqreturn_t paravirt_reched_interrupt(int irq, void *dev_id)
+{
+	scheduler_ipi();
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t paravirt_function_interrupt(int irq, void *dev_id)
+{
+	smp_call_function_interrupt();
+	return IRQ_HANDLED;
+}
+
+static void paravirt_prepare_cpus(unsigned int max_cpus)
+{
+	if (request_irq(MIPS_IRQ_MBOX0, paravirt_reched_interrupt,
+			IRQF_PERCPU | IRQF_NO_THREAD, "Scheduler",
+			paravirt_reched_interrupt)) {
+		panic("Cannot request_irq for SchedulerIPI");
+	}
+	if (request_irq(MIPS_IRQ_MBOX1, paravirt_function_interrupt,
+			IRQF_PERCPU | IRQF_NO_THREAD, "SMP-Call",
+			paravirt_function_interrupt)) {
+		panic("Cannot request_irq for SMP-Call");
+	}
+}
+
+struct plat_smp_ops paravirt_smp_ops = {
+	.send_ipi_single	= paravirt_send_ipi_single,
+	.send_ipi_mask		= paravirt_send_ipi_mask,
+	.init_secondary		= paravirt_init_secondary,
+	.smp_finish		= paravirt_smp_finish,
+	.cpus_done		= paravirt_cpus_done,
+	.boot_secondary		= paravirt_boot_secondary,
+	.smp_setup		= paravirt_smp_setup,
+	.prepare_cpus		= paravirt_prepare_cpus,
+};