1 files changed, 69 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
new file mode 100644
index 000000000000..676022e71791
--- /dev/null
+++ b/arch/x86/kernel/cpu/acrn.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACRN detection support
+ *
+ * Copyright (C) 2019 Intel Corporation. All rights reserved.
+ *
+ * Jason Chen CJ <jason.cj.chen@intel.com>
+ * Zhao Yakui <yakui.zhao@intel.com>
+ *
+ */
+
+#include <linux/interrupt.h>
+#include <asm/acrn.h>
+#include <asm/apic.h>
+#include <asm/desc.h>
+#include <asm/hypervisor.h>
+#include <asm/irq_regs.h>
+
+static uint32_t __init acrn_detect(void)
+{
+	return hypervisor_cpuid_base("ACRNACRNACRN\0\0", 0);
+}
+
+static void __init acrn_init_platform(void)
+{
+	/* Setup the IDT for ACRN hypervisor callback */
+	alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, acrn_hv_callback_vector);
+}
+
+static bool acrn_x2apic_available(void)
+{
+	/*
+	 * x2apic is not supported for now. Future enablement will have to check
+	 * X86_FEATURE_X2APIC to determine whether x2apic is supported in the
+	 * guest.
+	 */
+	return false;
+}
+
+static void (*acrn_intr_handler)(void);
+
+__visible void __irq_entry acrn_hv_vector_handler(struct pt_regs *regs)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	/*
+	 * The hypervisor requires that the APIC EOI should be acked.
+	 * If the APIC EOI is not acked, the APIC ISR bit for the
+	 * HYPERVISOR_CALLBACK_VECTOR will not be cleared and then it
+	 * will block the interrupt whose vector is lower than
+	 * HYPERVISOR_CALLBACK_VECTOR.
+	 */
+	entering_ack_irq();
+	inc_irq_stat(irq_hv_callback_count);
+
+	if (acrn_intr_handler)
+		acrn_intr_handler();
+
+	exiting_irq();
+	set_irq_regs(old_regs);
+}
+
+const __initconst struct hypervisor_x86 x86_hyper_acrn = {
+	.name                   = "ACRN",
+	.detect                 = acrn_detect,
+	.type			= X86_HYPER_ACRN,
+	.init.init_platform     = acrn_init_platform,
+	.init.x2apic_available  = acrn_x2apic_available,
+};