>From 35fca27b47edaa4c4b9bb3f932e67da7cf78b91a Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Tue, 25 Apr 2017 16:01:47 +0200 Subject: [PATCH] x86/amd: don't set X86_BUG_SYSRET_SS_ATTRS if forced to zero When running as Xen pv guest X86_BUG_SYSRET_SS_ATTRS must not be set on AMD cpus. Xen will disable this via setup_clear_cpu_cap(), so test cpu_caps_cleared to not have disabled this bug. Signed-off-by: Juergen Gross --- arch/x86/kernel/cpu/amd.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index c36140d788fe..f659b6f534b7 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -800,7 +800,9 @@ static void init_amd(struct cpuinfo_x86 *c) set_cpu_cap(c, X86_FEATURE_3DNOWPREFETCH); /* AMD CPUs don't reset SS attributes on SYSRET */ - set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS); + if (!test_bit(X86_BUG_SYSRET_SS_ATTRS, + (unsigned long *)cpu_caps_cleared)) + set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS); } #ifdef CONFIG_X86_32 -- 2.12.0