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| author | Matthew Whitehead <tedheadster@gmail.com> | 2018-09-21 17:20:41 -0400 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2018-09-22 11:47:39 +0200 |
| commit | 2893cc8ff892fa74972d8dc0e1d0dc65116daaa3 (patch) | |
| tree | 849969e84a3b820861b15734b52f37458805fb74 /arch/x86/kernel/cpu/common.c | |
| parent | 03b099bdcdf7125d4a63dc9ddeefdd454e05123d (diff) | |
| download | lwn-2893cc8ff892fa74972d8dc0e1d0dc65116daaa3.tar.gz lwn-2893cc8ff892fa74972d8dc0e1d0dc65116daaa3.zip | |
x86/CPU: Change query logic so CPUID is enabled before testing
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
Diffstat (limited to 'arch/x86/kernel/cpu/common.c')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 44c4ef3d989b..658c85d16a9b 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1076,6 +1076,9 @@ 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); @@ -1093,7 +1096,6 @@ 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); } |