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12209993e9
There is one user of __kernel_fpu_begin() and before invoking it,
it invokes preempt_disable(). So it could invoke kernel_fpu_begin()
right away. The 32bit version of arch_efi_call_virt_setup() and
arch_efi_call_virt_teardown() does this already.
The comment above *kernel_fpu*() claims that before invoking
__kernel_fpu_begin() preemption should be disabled and that KVM is a
good example of doing it. Well, KVM doesn't do that since commit
f775b13eed ("x86,kvm: move qemu/guest FPU switching out to vcpu_run")
so it is not an example anymore.
With EFI gone as the last user of __kernel_fpu_{begin|end}(), both can
be made static and not exported anymore.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm ML <kvm@vger.kernel.org>
Cc: linux-efi <linux-efi@vger.kernel.org>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20181129150210.2k4mawt37ow6c2vq@linutronix.de
35 lines
1.0 KiB
C
35 lines
1.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 1994 Linus Torvalds
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*
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* Pentium III FXSR, SSE support
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* General FPU state handling cleanups
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* Gareth Hughes <gareth@valinux.com>, May 2000
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* x86-64 work by Andi Kleen 2002
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*/
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#ifndef _ASM_X86_FPU_API_H
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#define _ASM_X86_FPU_API_H
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/*
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* Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It
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* disables preemption so be careful if you intend to use it for long periods
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* of time.
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* If you intend to use the FPU in softirq you need to check first with
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* irq_fpu_usable() if it is possible.
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*/
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extern void kernel_fpu_begin(void);
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extern void kernel_fpu_end(void);
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extern bool irq_fpu_usable(void);
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/*
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* Query the presence of one or more xfeatures. Works on any legacy CPU as well.
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*
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* If 'feature_name' is set then put a human-readable description of
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* the feature there as well - this can be used to print error (or success)
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* messages.
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*/
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extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name);
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#endif /* _ASM_X86_FPU_API_H */
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