Commit-ID: 60e528d6ce3f60a058bbb64f8acb2a07f84b172a Gitweb: https://git.kernel.org/tip/60e528d6ce3f60a058bbb64f8acb2a07f84b172a Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> AuthorDate: Wed, 3 Apr 2019 18:41:32 +0200 Committer: Borislav Petkov <bp@xxxxxxx> CommitDate: Tue, 9 Apr 2019 19:27:46 +0200 x86/fpu: Remove preempt_disable() in fpu__clear() The preempt_disable() section was introduced in commit a10b6a16cdad8 ("x86/fpu: Make the fpu state change in fpu__clear() scheduler-atomic") and it was said to be temporary. fpu__initialize() initializes the FPU struct to its initial value and then sets ->initialized to 1. The last part is the important one. The content of the state does not matter because it gets set via copy_init_fpstate_to_fpregs(). A preemption here has little meaning because the registers will always be set to the same content after copy_init_fpstate_to_fpregs(). A softirq with a kernel_fpu_begin() could also force to save FPU's registers after fpu__initialize() without changing the outcome here. Remove the preempt_disable() section in fpu__clear(), preemption here does not hurt. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Dave Hansen <dave.hansen@xxxxxxxxx> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: "Jason A. Donenfeld" <Jason@xxxxxxxxx> Cc: kvm ML <kvm@xxxxxxxxxxxxxxx> Cc: Nicolai Stange <nstange@xxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxxx> Cc: x86-ml <x86@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20190403164156.19645-4-bigeasy@xxxxxxxxxxxxx --- arch/x86/kernel/fpu/core.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 1d3ae7988f7f..1940319268ae 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -366,11 +366,9 @@ void fpu__clear(struct fpu *fpu) * Make sure fpstate is cleared and initialized. */ if (static_cpu_has(X86_FEATURE_FPU)) { - preempt_disable(); fpu__initialize(fpu); user_fpu_begin(); copy_init_fpstate_to_fpregs(); - preempt_enable(); } }
