[RFC PATCH 02/15] x86/acrn: Add two APIs to add/remove driver-specific upcall ISR handler

[Zhao Yakui]

After the ACRN hypervisor sends the upcall notify interrupt, the upcall ISR
handler will be served. Now almost nothing is handled in upcall ISR handler
except acking EOI.
The driver-specific ISR handler is registered by the driver, which helps to
handle the real notification from ACRN hypervisor.
This is similar to that in XEN/HyperV.

Co-developed-by: Jason Chen CJ <jason.cj.chen@xxxxxxxxx>
Signed-off-by: Jason Chen CJ <jason.cj.chen@xxxxxxxxx>
Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx>
---
 arch/x86/include/asm/acrn.h |  3 +++
 arch/x86/kernel/cpu/acrn.c  | 12 ++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/arch/x86/include/asm/acrn.h b/arch/x86/include/asm/acrn.h
index 4adb13f..857e6244 100644
--- a/arch/x86/include/asm/acrn.h
+++ b/arch/x86/include/asm/acrn.h
@@ -8,4 +8,7 @@ extern void acrn_hv_callback_vector(void);
 #endif
 
 extern void acrn_hv_vector_handler(struct pt_regs *regs);
+
+extern void acrn_setup_intr_irq(void (*handler)(void));
+extern void acrn_remove_intr_irq(void);
 #endif /* _ASM_X86_ACRN_H */
diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
index 95db5c4..a1ce52a 100644
--- a/arch/x86/kernel/cpu/acrn.c
+++ b/arch/x86/kernel/cpu/acrn.c
@@ -56,6 +56,18 @@ __visible void __irq_entry acrn_hv_vector_handler(struct pt_regs *regs)
 	set_irq_regs(old_regs);
 }
 
+void acrn_setup_intr_irq(void (*handler)(void))
+{
+	acrn_intr_handler = handler;
+}
+EXPORT_SYMBOL_GPL(acrn_setup_intr_irq);
+
+void acrn_remove_intr_irq(void)
+{
+	acrn_intr_handler = NULL;
+}
+EXPORT_SYMBOL_GPL(acrn_remove_intr_irq);
+
 const __initconst struct hypervisor_x86 x86_hyper_acrn = {
 	.name                   = "ACRN",
 	.detect                 = acrn_detect,
-- 
2.7.4