[PATCH v4 02/15] x86/xen: use specific Xen pv interrupt entry for MCE

[Juergen Gross <jgross@xxxxxxxx>]

Xen PV guests don't use IST. For machine check interrupts switch to
the same model as debug interrupts.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 arch/x86/include/asm/idtentry.h |  3 +++
 arch/x86/xen/enlighten_pv.c     | 16 +++++++++++++++-
 arch/x86/xen/xen-asm.S          |  2 +-
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 247a60a47331..5dd64404715a 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -585,6 +585,9 @@ DECLARE_IDTENTRY_MCE(X86_TRAP_MC,   exc_machine_check);
 #else
 DECLARE_IDTENTRY_RAW(X86_TRAP_MC,      exc_machine_check);
 #endif
+#ifdef CONFIG_XEN_PV
+DECLARE_IDTENTRY_RAW(X86_TRAP_MC,      xenpv_exc_machine_check);
+#endif
 #endif
 
 /* NMI */
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 4409306364dc..9f5e44c1f70a 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -583,6 +583,20 @@ DEFINE_IDTENTRY_RAW(xenpv_exc_debug)
                exc_debug(regs);
 }
 
+#ifdef CONFIG_X86_MCE
+DEFINE_IDTENTRY_RAW(xenpv_exc_machine_check)
+{
+       /*
+        * There's no IST on Xen PV, but we still need to dispatch
+        * to the correct handler.
+        */
+       if (user_mode(regs))
+               noist_exc_machine_check(regs);
+       else
+               exc_machine_check(regs);
+}
+#endif
+
 struct trap_array_entry {
        void (*orig)(void);
        void (*xen)(void);
@@ -603,7 +617,7 @@ static struct trap_array_entry trap_array[] = {
        TRAP_ENTRY_REDIR(exc_debug,                     true  ),
        TRAP_ENTRY(exc_double_fault,                    true  ),
 #ifdef CONFIG_X86_MCE
-       TRAP_ENTRY(exc_machine_check,                   true  ),
+       TRAP_ENTRY_REDIR(exc_machine_check,             true  ),
 #endif
        TRAP_ENTRY_REDIR(exc_nmi,                       true  ),
        TRAP_ENTRY(exc_int3,                            false ),
diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index 1cb0e84b9161..bc2586730a5b 100644
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -172,7 +172,7 @@ xen_pv_trap asm_exc_spurious_interrupt_bug
 xen_pv_trap asm_exc_coprocessor_error
 xen_pv_trap asm_exc_alignment_check
 #ifdef CONFIG_X86_MCE
-xen_pv_trap asm_exc_machine_check
+xen_pv_trap asm_xenpv_exc_machine_check
 #endif /* CONFIG_X86_MCE */
 xen_pv_trap asm_exc_simd_coprocessor_error
 #ifdef CONFIG_IA32_EMULATION
-- 
2.26.2