[PATCH v3 01/15] x86/xen: use specific Xen pv interrupt entry for MCE

Juergen Gross
2020-12-17T09:32:50Z

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@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---
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