From: Borislav Petkov <bp@alien8.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, "Chang S. Bae" <chang.seok.bae@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Arjan van de Ven <arjan@linux.intel.com>,
kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
"Liu, Jing2" <jing2.liu@intel.com>,
Sean Christopherson <seanjc@google.com>,
Xiaoyao Li <xiaoyao.li@intel.com>
Subject: Re: [patch V2 23/30] x86/fpu: Move fpregs_restore_userregs() to core
Date: Tue, 19 Oct 2021 20:11:07 +0200 [thread overview]
Message-ID: <YW8KO9sfDeB72yUd@zn.tnic> (raw)
In-Reply-To: <20211015011539.686806639@linutronix.de>
On Fri, Oct 15, 2021 at 03:16:30AM +0200, Thomas Gleixner wrote:
> +static inline void fpregs_deactivate(struct fpu *fpu)
> +{
> + __this_cpu_write(fpu_fpregs_owner_ctx, NULL);
> + trace_x86_fpu_regs_deactivated(fpu);
> +}
> +
> +static inline void fpregs_activate(struct fpu *fpu)
> +{
> + __this_cpu_write(fpu_fpregs_owner_ctx, fpu);
> + trace_x86_fpu_regs_activated(fpu);
You're silently changing here the percpu writes to the __ variants and
AFAICT, there's no difference on x86:
# arch/x86/kernel/fpu/context.h:50: this_cpu_write(fpu_fpregs_owner_ctx, fpu);
#APP
# 50 "arch/x86/kernel/fpu/context.h" 1
movq %rsi, %gs:fpu_fpregs_owner_ctx(%rip) # fpu, fpu_fpregs_owner_ctx
# 0 "" 2
VS
# arch/x86/kernel/fpu/context.h:50: __this_cpu_write(fpu_fpregs_owner_ctx, fpu);
#APP
# 50 "arch/x86/kernel/fpu/context.h" 1
movq %rsi, %gs:fpu_fpregs_owner_ctx(%rip) # fpu, fpu_fpregs_owner_ctx
# 0 "" 2
except maybe the __ variant doesn't use the "volatile" inline asm
qualifier in the lower-level raw_cpu_write_8() vs this_cpu_write_8().
And there's the preemption check, ofc.
Or maybe this could have something to do with RT...?
Commit message could mention this change, though.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-10-19 18:11 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-15 1:15 [patch V2 00/30] x86/fpu: Preparatory cleanups for AMX support (part 1) Thomas Gleixner
2021-10-15 1:15 ` [patch V2 01/30] x86/fpu: Remove pointless argument from switch_fpu_finish() Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:15 ` [patch V2 02/30] x86/fpu: Update stale comments Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:15 ` [patch V2 03/30] x86/pkru: Remove useless include Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:15 ` [patch V2 04/30] x86/fpu: Restrict xsaves()/xrstors() to independent states Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 05/30] x86/fpu: Cleanup the on_boot_cpu clutter Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 06/30] x86/fpu: Remove pointless memset in fpu_clone() Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 07/30] x86/process: Clone FPU in copy_thread() Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 08/30] x86/fpu: Do not inherit FPU context for kernel and IO worker threads Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 09/30] x86/fpu: Cleanup xstate xcomp_bv initialization Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 10/30] x86/fpu/xstate: Provide and use for_each_xfeature() Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 11/30] x86/fpu/xstate: Mark all init only functions __init Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 12/30] x86/fpu: Move KVMs FPU swapping to FPU core Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 13/30] x86/fpu: Replace KVMs home brewed FPU copy from user Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 14/30] x86/fpu: Rework copy_xstate_to_uabi_buf() Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 15/30] x86/fpu: Replace KVMs home brewed FPU copy to user Thomas Gleixner
2021-10-21 15:12 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 16/30] x86/fpu: Mark fpu__init_prepare_fx_sw_frame() as __init Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 17/30] x86/fpu: Move context switch and exit to user inlines into sched.h Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 18/30] x86/fpu: Clean up cpu feature tests Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] x86/fpu: Clean up CPU " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 19/30] x86/fpu: Make os_xrstor_booting() private Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 20/30] x86/fpu: Move os_xsave() and os_xrstor() to core Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 21/30] x86/fpu: Move legacy ASM wrappers " Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 22/30] x86/fpu: Make WARN_ON_FPU() private Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 23/30] x86/fpu: Move fpregs_restore_userregs() to core Thomas Gleixner
2021-10-19 18:11 ` Borislav Petkov [this message]
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 24/30] x86/fpu: Move mxcsr related code " Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 25/30] x86/fpu: Move fpstate functions to api.h Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 26/30] x86/fpu: Remove internal.h dependency from fpu/signal.h Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 27/30] x86/sev: Include fpu/xcr.h Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 28/30] x86/fpu: Mop up the internal.h leftovers Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 29/30] x86/fpu: Replace the includes of fpu/internal.h Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-10-15 1:16 ` [patch V2 30/30] x86/fpu: Provide a proper function for ex_handler_fprestore() Thomas Gleixner
2021-10-20 13:44 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
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