[Xen-devel] Patch "x86/amd: revert commit 944e0fc51a89c9827b9" has been added to the 4.9-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    x86/amd: revert commit 944e0fc51a89c9827b9

to the 4.9-stable tree which can be found at:
    
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-amd-revert-commit-944e0fc51a89c9827b9.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


From foo@baz Sat Jun  2 15:10:07 CEST 2018
From: Juergen Gross <jgross@xxxxxxxx>
Date: Wed, 30 May 2018 13:09:56 +0200
Subject: x86/amd: revert commit 944e0fc51a89c9827b9
To: stable@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
Cc: dwmw@xxxxxxxxxxxx, boris.ostrovsky@xxxxxxxxxx, Juergen Gross 
<jgross@xxxxxxxx>
Message-ID: <20180530110958.19413-2-jgross@xxxxxxxx>

From: Juergen Gross <jgross@xxxxxxxx>

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@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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
@@ -1977,8 +1977,10 @@ 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)


Patches currently in stable-queue which might be from jgross@xxxxxxxx are

queue-4.9/x86-amd-don-t-set-x86_bug_sysret_ss_attrs-when-running-under-xen.patch
queue-4.9/x86-amd-revert-commit-944e0fc51a89c9827b9.patch
queue-4.9/xen-set-cpu-capabilities-from-xen_start_kernel.patch

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