[tip: x86/paravirt] x86/xen: Use specific Xen pv interrupt entry for MCE

[tip-bot2 for Juergen Gross]

The following commit has been merged into the x86/paravirt branch of tip:

Commit-ID:     c3d7fa6684b5b3a07a48fc379d27bfb8a96661d9
Gitweb:        https://git.kernel.org/tip/c3d7fa6684b5b3a07a48fc379d27bfb8a96661d9
Author:        Juergen Gross <jgross@xxxxxxxx>
AuthorDate:    Wed, 20 Jan 2021 14:55:42 +01:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Wed, 10 Feb 2021 12:07:10 +01:00

x86/xen: Use specific Xen pv interrupt entry for MCE

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>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20210120135555.32594-3-jgross@xxxxxxxx
---
 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 f656aab..616909e 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 9a5a50c..9db1d31 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -590,6 +590,20 @@ DEFINE_IDTENTRY_RAW(exc_xen_unknown_trap)
 	BUG();
 }
 
+#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);
@@ -610,7 +624,7 @@ 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 53cf8aa..cd330ce 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