linux-kernel - [PATCH] x86/speculation/mds: Apply more accurate check on hypervisor platform

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Date:   Thu, 25 Jul 2019 10:39:09 +0800
From:   Zhenzhong Duan <zhenzhong.duan@...cle.com>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, Zhenzhong Duan <zhenzhong.duan@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: [PATCH] x86/speculation/mds: Apply more accurate check on hypervisor platform

X86_HYPER_NATIVE isn't accurate for checking if running on native
platform, e.g. CONFIG_HYPERVISOR_GUEST isn't set or "nopv" is enabled.

Checking cpu flag X86_FEATURE_HYPERVISOR to determine if it's running
on native platform is more accurate.

This still doesn't consider the old platform where even
X86_FEATURE_HYPERVISOR is unsupported, e.g. vmware.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...cle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Juergen Gross <jgross@...e.com>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
---
 arch/x86/kernel/cpu/bugs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 66ca906..801ecd1 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1226,7 +1226,7 @@ static ssize_t l1tf_show_state(char *buf)
 
 static ssize_t mds_show_state(char *buf)
 {
-	if (!hypervisor_is_type(X86_HYPER_NATIVE)) {
+	if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
 		return sprintf(buf, "%s; SMT Host state unknown\n",
 			       mds_strings[mds_mitigation]);
 	}
-- 
1.8.3.1