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

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

[Zhenzhong Duan]

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@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.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

[tip:x86/urgent] x86/speculation/mds: Apply more accurate check on hypervisor platform

[tip-bot for Zhenzhong Duan]

Commit-ID:  517c3ba00916383af6411aec99442c307c23f684
Gitweb:     https://git.kernel.org/tip/517c3ba00916383af6411aec99442c307c23f684
Author:     Zhenzhong Duan <zhenzhong.duan@oracle.com>
AuthorDate: Thu, 25 Jul 2019 10:39:09 +0800
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 25 Jul 2019 12:51:55 +0200

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 the CPU feature bit X86_FEATURE_HYPERVISOR to determine if it's
running on native platform is more accurate.

This still doesn't cover the platforms on which X86_FEATURE_HYPERVISOR is
unsupported, e.g. VMware, but there is nothing which can be done about this
scenario.

Fixes: 8a4b06d391b0 ("x86/speculation/mds: Add sysfs reporting for MDS")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1564022349-17338-1-git-send-email-zhenzhong.duan@oracle.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 66ca906aa790..801ecd1c3fd5 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]);
 	}