[PATCH 02/17] x86/acrn: Introduce acrn_{setup, remove}_intr_handler()

[shuo . a . liu]

From: Shuo Liu <shuo.a.liu@xxxxxxxxx>

The ACRN Hypervisor builds an I/O request when a trapped I/O access
happens in User VM. Then, ACRN Hypervisor issues an upcall by sending
a notification interrupt to the Service VM. HSM in the Service VM needs
to hook the notification interrupt to handle I/O requests.

Notification interrupts from ACRN Hypervisor are already supported and
a, currently uninitialized, callback called.

Export two APIs for HSM to setup/remove its callback.

Originally-by: Yakui Zhao <yakui.zhao@xxxxxxxxx>
Signed-off-by: Shuo Liu <shuo.a.liu@xxxxxxxxx>
Reviewed-by: Zhi Wang <zhi.a.wang@xxxxxxxxx>
Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Fengwei Yin <fengwei.yin@xxxxxxxxx>
Cc: Zhi Wang <zhi.a.wang@xxxxxxxxx>
Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
Cc: Yu Wang <yu1.wang@xxxxxxxxx>
Cc: Reinette Chatre <reinette.chatre@xxxxxxxxx>
---
 arch/x86/include/asm/acrn.h |  8 ++++++++
 arch/x86/kernel/cpu/acrn.c  | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+)
 create mode 100644 arch/x86/include/asm/acrn.h

diff --git a/arch/x86/include/asm/acrn.h b/arch/x86/include/asm/acrn.h
new file mode 100644
index 000000000000..ff259b69cde7
--- /dev/null
+++ b/arch/x86/include/asm/acrn.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_ACRN_H
+#define _ASM_X86_ACRN_H
+
+void acrn_setup_intr_handler(void (*handler)(void));
+void acrn_remove_intr_handler(void);
+
+#endif /* _ASM_X86_ACRN_H */
diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
index 0b2c03943ac6..bd1d7e759a0f 100644
--- a/arch/x86/kernel/cpu/acrn.c
+++ b/arch/x86/kernel/cpu/acrn.c
@@ -9,7 +9,11 @@
  *
  */
 
+#define pr_fmt(fmt) "acrn: " fmt
+
 #include <linux/interrupt.h>
+
+#include <asm/acrn.h>
 #include <asm/apic.h>
 #include <asm/cpufeatures.h>
 #include <asm/desc.h>
@@ -55,6 +59,21 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_acrn_hv_callback)
 	set_irq_regs(old_regs);
 }
 
+void acrn_setup_intr_handler(void (*handler)(void))
+{
+	if (acrn_intr_handler)
+		pr_warn("Overwrite the acrn_intr_handler.\n");
+
+	acrn_intr_handler = handler;
+}
+EXPORT_SYMBOL_GPL(acrn_setup_intr_handler);
+
+void acrn_remove_intr_handler(void)
+{
+	acrn_intr_handler = NULL;
+}
+EXPORT_SYMBOL_GPL(acrn_remove_intr_handler);
+
 const __initconst struct hypervisor_x86 x86_hyper_acrn = {
 	.name                   = "ACRN",
 	.detect                 = acrn_detect,
-- 
2.28.0