linux-kernel - [PATCH 4.9 15/61] x86/amd: revert commit 944e0fc51a89c9827b9

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Message-Id: <20180605170118.591023264@linuxfoundation.org>
Date:   Tue,  5 Jun 2018 19:01:36 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "dwmw@...zon.co.uk, boris.ostrovsky@...cle.com, Juergen Gross" 
        <jgross@...e.com>, Juergen Gross <jgross@...e.com>
Subject: [PATCH 4.9 15/61] x86/amd: revert commit 944e0fc51a89c9827b9

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Juergen Gross <jgross@...e.com>

Revert commit 944e0fc51a89c9827b98813d65dc083274777c7f ("x86/amd: don't
set X86_BUG_SYSRET_SS_ATTRS when running under Xen") as it is lacking
a prerequisite patch and is making things worse.

Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/cpu/amd.c |    5 ++---
 arch/x86/xen/enlighten.c  |    4 +++-
 2 files changed, 5 insertions(+), 4 deletions(-)

--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -857,9 +857,8 @@ static void init_amd(struct cpuinfo_x86
 		if (cpu_has(c, X86_FEATURE_3DNOW) || cpu_has(c, X86_FEATURE_LM))
 			set_cpu_cap(c, X86_FEATURE_3DNOWPREFETCH);
 
-	/* AMD CPUs don't reset SS attributes on SYSRET, Xen does. */
-	if (!cpu_has(c, X86_FEATURE_XENPV))
-		set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
+	/* AMD CPUs don't reset SS attributes on SYSRET */
+	set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
 }
 
 #ifdef CONFIG_X86_32
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1980,8 +1980,10 @@ EXPORT_SYMBOL_GPL(xen_hvm_need_lapic);
 
 static void xen_set_cpu_features(struct cpuinfo_x86 *c)
 {
-	if (xen_pv_domain())
+	if (xen_pv_domain()) {
+		clear_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
 		set_cpu_cap(c, X86_FEATURE_XENPV);
+	}
 }
 
 static void xen_pin_vcpu(int cpu)