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