x86/entry: Convert XEN hypercall vector to IDTENTRY_SYSVEC

Convert the last oldstyle defined vector to IDTENTRY_SYSVEC:

  - Implement the C entry point with DEFINE_IDTENTRY_SYSVEC
  - Emit the ASM stub with DECLARE_IDTENTRY_SYSVEC
  - Remove the ASM idtentries in 64-bit
  - Remove the BUILD_INTERRUPT entries in 32-bit
  - Remove the old prototypes

Fixup the related XEN code by providing the primary C entry point in x86 to
avoid cluttering the generic code with X86'isms.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200521202119.741950104@linutronix.de

arch/x86/entry/entry_32.S

@@ -1340,11 +1340,6 @@ SYM_FUNC_START(xen_failsafe_callback)
 SYM_FUNC_END(xen_failsafe_callback)
 #endif /* CONFIG_XEN_PV */
 
-#ifdef CONFIG_XEN_PVHVM
-BUILD_INTERRUPT3(xen_hvm_callback_vector, HYPERVISOR_CALLBACK_VECTOR,
-		 xen_evtchn_do_upcall)
-#endif
-
 SYM_CODE_START_LOCAL_NOALIGN(handle_exception)
 	/* the function address is in %gs's slot on the stack */
 	SAVE_ALL switch_stacks=1 skip_gs=1 unwind_espfix=1

arch/x86/entry/entry_64.S

@@ -1111,11 +1111,6 @@ SYM_CODE_START(xen_failsafe_callback)
 SYM_CODE_END(xen_failsafe_callback)
 #endif /* CONFIG_XEN_PV */
 
-#ifdef CONFIG_XEN_PVHVM
-apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \
-	xen_hvm_callback_vector xen_evtchn_do_upcall
-#endif
-
 /*
  * Save all registers in pt_regs, and switch gs if needed.
  * Use slow, but surefire "are we in kernel?" check.

arch/x86/include/asm/idtentry.h

@@ -644,6 +644,10 @@ DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_STIMER0_VECTOR,	sysvec_hyperv_stimer0);
 DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_CALLBACK_VECTOR,	sysvec_acrn_hv_callback);
 #endif
 
+#ifdef CONFIG_XEN_PVHVM
+DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_CALLBACK_VECTOR,	sysvec_xen_hvm_callback);
+#endif
+
 #undef X86_TRAP_OTHER
 
 #endif

arch/x86/xen/enlighten_hvm.c

@@ -13,6 +13,7 @@
 #include <asm/smp.h>
 #include <asm/reboot.h>
 #include <asm/setup.h>
+#include <asm/idtentry.h>
 #include <asm/hypervisor.h>
 #include <asm/e820/api.h>
 #include <asm/early_ioremap.h>
@@ -118,6 +119,17 @@ static void __init init_hvm_pv_info(void)
 		this_cpu_write(xen_vcpu_id, smp_processor_id());
 }
 
+DEFINE_IDTENTRY_SYSVEC(sysvec_xen_hvm_callback)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	inc_irq_stat(irq_hv_callback_count);
+
+	xen_hvm_evtchn_do_upcall();
+
+	set_irq_regs(old_regs);
+}
+
 #ifdef CONFIG_KEXEC_CORE
 static void xen_hvm_shutdown(void)
 {

drivers/xen/events/events_base.c

@@ -37,6 +37,7 @@
 #ifdef CONFIG_X86
 #include <asm/desc.h>
 #include <asm/ptrace.h>
+#include <asm/idtentry.h>
 #include <asm/irq.h>
 #include <asm/io_apic.h>
 #include <asm/i8259.h>
@@ -1236,9 +1237,6 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
 	struct pt_regs *old_regs = set_irq_regs(regs);
 
 	irq_enter();
-#ifdef CONFIG_X86
-	inc_irq_stat(irq_hv_callback_count);
-#endif
 
 	__xen_evtchn_do_upcall();
 
@@ -1658,7 +1656,7 @@ static __init void xen_alloc_callback_vector(void)
 		return;
 
 	pr_info("Xen HVM callback vector for event delivery is enabled\n");
-	alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, xen_hvm_callback_vector);
+	alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_xen_hvm_callback);
 }
 #else
 void xen_setup_callback_vector(void) {}

include/xen/events.h

@@ -90,13 +90,6 @@ unsigned int irq_from_evtchn(evtchn_port_t evtchn);
 int irq_from_virq(unsigned int cpu, unsigned int virq);
 evtchn_port_t evtchn_from_irq(unsigned irq);
 
-#ifdef CONFIG_XEN_PVHVM
-/* Xen HVM evtchn vector callback */
-void xen_hvm_callback_vector(void);
-#ifdef CONFIG_TRACING
-#define trace_xen_hvm_callback_vector xen_hvm_callback_vector
-#endif
-#endif
 int xen_set_callback_via(uint64_t via);
 void xen_evtchn_do_upcall(struct pt_regs *regs);
 void xen_hvm_evtchn_do_upcall(void);