x86/entry: Switch XEN/PV hypercall entry to IDTENTRY

Convert the XEN/PV hypercall to IDTENTRY:

  - Emit the ASM stub with DECLARE_IDTENTRY
  - Remove the ASM idtentry in 64-bit
  - Remove the open coded ASM entry code in 32-bit
  - Remove the old prototypes

The handler stubs need to stay in ASM code as they need corner case handling
and adjustment of the stack pointer.

Provide a new C function which invokes the entry/exit handling and calls
into the XEN handler on the interrupt stack if required.

The exit code is slightly different from the regular idtentry_exit() on
non-preemptible kernels. If the hypercall is preemptible and need_resched()
is set then XEN provides a preempt hypercall scheduling function.

Move this functionality into the entry code so it can use the existing
idtentry functionality.

[ mingo: Build fixes. ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Juergen Gross <jgross@suse.com>
Tested-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20200521202118.055270078@linutronix.de

1 files changed, 7 insertions, 12 deletions

diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index 095be1d66f31..39a5580f8feb 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -215,17 +215,7 @@ bool xen_running_on_version_or_later(unsigned int major, unsigned int minor);
 void xen_efi_runtime_setup(void);
 
 
-#ifdef CONFIG_PREEMPTION
-
-static inline void xen_preemptible_hcall_begin(void)
-{
-}
-
-static inline void xen_preemptible_hcall_end(void)
-{
-}
-
-#else
+#if defined(CONFIG_XEN_PV) && !defined(CONFIG_PREEMPTION)
 
 DECLARE_PER_CPU(bool, xen_in_preemptible_hcall);
 
@@ -239,6 +229,11 @@ static inline void xen_preemptible_hcall_end(void)
 	__this_cpu_write(xen_in_preemptible_hcall, false);
 }
 
-#endif /* CONFIG_PREEMPTION */
+#else
+
+static inline void xen_preemptible_hcall_begin(void) { }
+static inline void xen_preemptible_hcall_end(void) { }
+
+#endif /* CONFIG_XEN_PV && !CONFIG_PREEMPTION */
 
 #endif /* INCLUDE_XEN_OPS_H */