Messages in this thread Patch in this message | | | From | Andy Lutomirski <> | Subject | [RFC PATCH 3/6] x86/cpu: Re-apply forced caps every time cpu caps are re-read | Date | Mon, 5 Dec 2016 17:01:12 -0800 |
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Calling get_cpu_cap() will reset a bunch of CPU features. This will cause the system to lose track of force-set and force-cleared featueres in the words that are reset until the end of CPU initialization. This can cause X86_FEATURE_FPU, for example, to change back and forth during boot and potentially confuse CPU setup.
To minimize the chance of confusion, re-apply forced caps every time get_cpu_cap() is called.
Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/kernel/cpu/common.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 347ae0a19380..24e1e4004d42 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -758,6 +758,13 @@ void get_cpu_cap(struct cpuinfo_x86 *c) c->x86_capability[CPUID_8000_000A_EDX] = cpuid_edx(0x8000000a); init_scattered_cpuid_features(c); + + /* + * Clear/Set all flags overridden by options, after probe. + * This needs to happen each time we re-probe, which may happen + * several times during CPU initialization. + */ + apply_forced_caps(c); } static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c) -- 2.9.3
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