[PATCH 08/18] xen: add xen nmi trap entry

Andy Lutomirski
2017-10-26T08:27:33Z

From: Juergen Gross <jgross@suse.com>

Instead of trying to execute any NMI via the bare metal's NMI trap
handler use a Xen specific one for pv domains, like we do for e.g.
debug traps. As in a pv domain the NMI is handled via the normal
kernel stack this is the correct thing to do.

This will enable us to get rid of the very fragile and questionable
dependencies between the bare metal NMI handler and Xen assumptions
believed to be broken anyway.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/entry/entry_64.S | 2 +-
arch/x86/include/asm/traps.h | 2 +-
arch/x86/xen/enlighten_pv.c | 2 +-
arch/x86/xen/xen-asm_64.S | 2 +-
4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index c855ee91a3a5..bf650fad94ce 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1074,6 +1074,7 @@ idtentry int3 do_int3 has_error_code=0 paranoid=1 shift_ist=DEBUG_STACK
idtentry stack_segment do_stack_segment has_error_code=1

#ifdef CONFIG_XEN
+idtentry xennmi do_nmi has_error_code=0
idtentry xendebug do_debug has_error_code=0
idtentry xenint3 do_int3 has_error_code=0
#endif
@@ -1236,7 +1237,6 @@ ENTRY(error_exit)
END(error_exit)

/* Runs on exception stack */
-/* XXX: broken on Xen PV */
ENTRY(nmi)
UNWIND_HINT_IRET_REGS
/*
diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
index 5545f6459bf5..26f1a88e42da 100644
--- a/arch/x86/include/asm/traps.h
+++ b/arch/x86/include/asm/traps.h
@@ -37,9 +37,9 @@ asmlinkage void simd_coprocessor_error(void);

#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)
asmlinkage void xen_divide_error(void);
+asmlinkage void xen_xennmi(void);
asmlinkage void xen_xendebug(void);
asmlinkage void xen_xenint3(void);
-asmlinkage void xen_nmi(void);
asmlinkage void xen_overflow(void);
asmlinkage void xen_bounds(void);
asmlinkage void xen_invalid_op(void);
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 69b9deff7e5c..8da4eff19c2a 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -600,7 +600,7 @@ static struct trap_array_entry trap_array[] = {
#ifdef CONFIG_X86_MCE
{ machine_check, xen_machine_check, true },
#endif
- { nmi, xen_nmi, true },
+ { nmi, xen_xennmi, true },
{ overflow, xen_overflow, false },
#ifdef CONFIG_IA32_EMULATION
{ entry_INT80_compat, xen_entry_INT80_compat, false },
diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index dae2cc33afb5..286ecc198562 100644
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -29,7 +29,7 @@ xen_pv_trap debug
xen_pv_trap xendebug
xen_pv_trap int3
xen_pv_trap xenint3
-xen_pv_trap nmi
+xen_pv_trap xennmi
xen_pv_trap overflow
xen_pv_trap bounds
xen_pv_trap invalid_op
--
2.13.6