Messages in this thread Patch in this message |  | | From | Ben Hutchings <> | Date | Sat, 22 Sep 2018 01:15:42 +0100 | Subject | [PATCH 3.16 01/63] x86/fpu: Fix the 'nofxsr' boot parameter to also clear X86_FEATURE_FXSR_OPT |
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3.16.58-rc1 review patch. If anyone has any objections, please let me know.
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From: Ingo Molnar <mingo@kernel.org>
commit d364a7656c1855c940dfa4baf4ebcc3c6a9e6fd2 upstream.
I tried to simulate an ancient CPU via this option, and found that it still has fxsr_opt enabled, confusing the FPU code.
Make the 'nofxsr' option also clear FXSR_OPT flag.
Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- arch/x86/kernel/cpu/common.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)
--- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -199,6 +199,15 @@ static int __init x86_noinvpcid_setup(ch } early_param("noinvpcid", x86_noinvpcid_setup); +static int __init x86_fxsr_setup(char *s) +{ + setup_clear_cpu_cap(X86_FEATURE_FXSR); + setup_clear_cpu_cap(X86_FEATURE_FXSR_OPT); + setup_clear_cpu_cap(X86_FEATURE_XMM); + return 1; +} +__setup("nofxsr", x86_fxsr_setup); + #ifdef CONFIG_X86_32 static int cachesize_override = -1; static int disable_x86_serial_nr = 1; @@ -210,14 +219,6 @@ static int __init cachesize_setup(char * } __setup("cachesize=", cachesize_setup); -static int __init x86_fxsr_setup(char *s) -{ - setup_clear_cpu_cap(X86_FEATURE_FXSR); - setup_clear_cpu_cap(X86_FEATURE_XMM); - return 1; -} -__setup("nofxsr", x86_fxsr_setup); - static int __init x86_sep_setup(char *s) { setup_clear_cpu_cap(X86_FEATURE_SEP);
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