1 files changed, 151 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/paravirt.c b/arch/loongarch/kernel/paravirt.c
new file mode 100644
index 0000000000..1633ed4f69
--- /dev/null
+++ b/arch/loongarch/kernel/paravirt.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/export.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/jump_label.h>
+#include <linux/kvm_para.h>
+#include <linux/static_call.h>
+#include <asm/paravirt.h>
+
+struct static_key paravirt_steal_enabled;
+struct static_key paravirt_steal_rq_enabled;
+
+static u64 native_steal_clock(int cpu)
+{
+	return 0;
+}
+
+DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
+
+#ifdef CONFIG_SMP
+static void pv_send_ipi_single(int cpu, unsigned int action)
+{
+	int min, old;
+	irq_cpustat_t *info = &per_cpu(irq_stat, cpu);
+
+	old = atomic_fetch_or(BIT(action), &info->message);
+	if (old)
+		return;
+
+	min = cpu_logical_map(cpu);
+	kvm_hypercall3(KVM_HCALL_FUNC_IPI, 1, 0, min);
+}
+
+#define KVM_IPI_CLUSTER_SIZE	(2 * BITS_PER_LONG)
+
+static void pv_send_ipi_mask(const struct cpumask *mask, unsigned int action)
+{
+	int i, cpu, min = 0, max = 0, old;
+	__uint128_t bitmap = 0;
+	irq_cpustat_t *info;
+
+	if (cpumask_empty(mask))
+		return;
+
+	action = BIT(action);
+	for_each_cpu(i, mask) {
+		info = &per_cpu(irq_stat, i);
+		old = atomic_fetch_or(action, &info->message);
+		if (old)
+			continue;
+
+		cpu = cpu_logical_map(i);
+		if (!bitmap) {
+			min = max = cpu;
+		} else if (cpu < min && cpu > (max - KVM_IPI_CLUSTER_SIZE)) {
+			/* cpu < min, and bitmap still enough */
+			bitmap <<= min - cpu;
+			min = cpu;
+		} else if (cpu > min && cpu < (min + KVM_IPI_CLUSTER_SIZE)) {
+			/* cpu > min, and bitmap still enough */
+			max = cpu > max ? cpu : max;
+		} else {
+			/*
+			 * With cpu, bitmap will exceed KVM_IPI_CLUSTER_SIZE,
+			 * send IPI here directly and skip the remaining CPUs.
+			 */
+			kvm_hypercall3(KVM_HCALL_FUNC_IPI, (unsigned long)bitmap,
+				      (unsigned long)(bitmap >> BITS_PER_LONG), min);
+			min = max = cpu;
+			bitmap = 0;
+		}
+		__set_bit(cpu - min, (unsigned long *)&bitmap);
+	}
+
+	if (bitmap)
+		kvm_hypercall3(KVM_HCALL_FUNC_IPI, (unsigned long)bitmap,
+			      (unsigned long)(bitmap >> BITS_PER_LONG), min);
+}
+
+static irqreturn_t pv_ipi_interrupt(int irq, void *dev)
+{
+	u32 action;
+	irq_cpustat_t *info;
+
+	/* Clear SWI interrupt */
+	clear_csr_estat(1 << INT_SWI0);
+	info = this_cpu_ptr(&irq_stat);
+	action = atomic_xchg(&info->message, 0);
+
+	if (action & SMP_RESCHEDULE) {
+		scheduler_ipi();
+		info->ipi_irqs[IPI_RESCHEDULE]++;
+	}
+
+	if (action & SMP_CALL_FUNCTION) {
+		generic_smp_call_function_interrupt();
+		info->ipi_irqs[IPI_CALL_FUNCTION]++;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void pv_init_ipi(void)
+{
+	int r, swi;
+
+	swi = get_percpu_irq(INT_SWI0);
+	if (swi < 0)
+		panic("SWI0 IRQ mapping failed\n");
+	irq_set_percpu_devid(swi);
+	r = request_percpu_irq(swi, pv_ipi_interrupt, "SWI0-IPI", &irq_stat);
+	if (r < 0)
+		panic("SWI0 IRQ request failed\n");
+}
+#endif
+
+static bool kvm_para_available(void)
+{
+	int config;
+	static int hypervisor_type;
+
+	if (!hypervisor_type) {
+		config = read_cpucfg(CPUCFG_KVM_SIG);
+		if (!memcmp(&config, KVM_SIGNATURE, 4))
+			hypervisor_type = HYPERVISOR_KVM;
+	}
+
+	return hypervisor_type == HYPERVISOR_KVM;
+}
+
+int __init pv_ipi_init(void)
+{
+	int feature;
+
+	if (!cpu_has_hypervisor)
+		return 0;
+	if (!kvm_para_available())
+		return 0;
+
+	feature = read_cpucfg(CPUCFG_KVM_FEATURE);
+	if (!(feature & KVM_FEATURE_IPI))
+		return 0;
+
+#ifdef CONFIG_SMP
+	mp_ops.init_ipi		= pv_init_ipi;
+	mp_ops.send_ipi_single	= pv_send_ipi_single;
+	mp_ops.send_ipi_mask	= pv_send_ipi_mask;
+#endif
+
+	return 0;
+}