linux-kernel - [GIT pull] x86 pti updates for 4.18

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Date:   Sun, 24 Jun 2018 13:29:00 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
cc:     LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...nel.org>
Subject: [GIT pull] x86 pti updates for 4.18

Linus,

please pull the latest x86-pti-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-pti-for-linus

Two small updates for the speculative distractions:

  - Make it more clear to the compiler that array_index_mask_nospec()
    is not subject for optimizations. It's not perfect, but ...

  - Don't report XEN PV guests as vulnerable because their mitigation state
    depends on the hypervisor. Report unknown and refer to the hypervisor
    requirement.

Thanks,

	tglx

------------------>
Dan Williams (1):
      x86/spectre_v1: Disable compiler optimizations over array_index_mask_nospec()

Jiri Kosina (1):
      x86/pti: Don't report XenPV as vulnerable


 arch/x86/include/asm/barrier.h | 2 +-
 arch/x86/kernel/cpu/bugs.c     | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index 042b5e892ed1..14de0432d288 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -38,7 +38,7 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
 {
 	unsigned long mask;
 
-	asm ("cmp %1,%2; sbb %0,%0;"
+	asm volatile ("cmp %1,%2; sbb %0,%0;"
 			:"=r" (mask)
 			:"g"(size),"r" (index)
 			:"cc");
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index cd0fda1fff6d..404df26b7de8 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -27,6 +27,7 @@
 #include <asm/pgtable.h>
 #include <asm/set_memory.h>
 #include <asm/intel-family.h>
+#include <asm/hypervisor.h>
 
 static void __init spectre_v2_select_mitigation(void);
 static void __init ssb_select_mitigation(void);
@@ -664,6 +665,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
 		if (boot_cpu_has(X86_FEATURE_PTI))
 			return sprintf(buf, "Mitigation: PTI\n");
 
+		if (hypervisor_is_type(X86_HYPER_XEN_PV))
+			return sprintf(buf, "Unknown (XEN PV detected, hypervisor mitigation required)\n");
+
 		break;
 
 	case X86_BUG_SPECTRE_V1: