From: Matthew Whitehead tedheadster@gmail.com
[ Upstream commit 2893cc8ff892fa74972d8dc0e1d0dc65116daaa3 ]
Presently we check first if CPUID is enabled. If it is not already enabled, then we next call identify_cpu_without_cpuid() and clear X86_FEATURE_CPUID.
Unfortunately, identify_cpu_without_cpuid() is the function where CPUID becomes _enabled_ on Cyrix 6x86/6x86L CPUs.
Reverse the calling sequence so that CPUID is first enabled, and then check a second time to see if the feature has now been activated.
[ bp: Massage commit message and remove trailing whitespace. ]
Suggested-by: Andy Lutomirski luto@amacapital.net Signed-off-by: Matthew Whitehead tedheadster@gmail.com Signed-off-by: Borislav Petkov bp@suse.de Reviewed-by: Andy Lutomirski luto@amacapital.net Cc: David Woodhouse dwmw@amazon.co.uk Cc: H. Peter Anvin hpa@zytor.com Cc: Ingo Molnar mingo@kernel.org Cc: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Link: http://lkml.kernel.org/r/20180921212041.13096-3-tedheadster@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/cpu/common.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index b33fdfa0ff49e..04622625f8e22 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1104,6 +1104,9 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c) memset(&c->x86_capability, 0, sizeof c->x86_capability); c->extended_cpuid_level = 0;
+ if (!have_cpuid_p()) + identify_cpu_without_cpuid(c); + /* cyrix could have cpuid enabled via c_identify()*/ if (have_cpuid_p()) { cpu_detect(c); @@ -1121,7 +1124,6 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c) if (this_cpu->c_bsp_init) this_cpu->c_bsp_init(c); } else { - identify_cpu_without_cpuid(c); setup_clear_cpu_cap(X86_FEATURE_CPUID); }