From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "Borislav Petkov" <bp@alien8.de>,
x86@kernel.org, "Ingo Molnar" <mingo@kernel.org>,
linux-kernel@vger.kernel.org, "Andy Lutomirski" <luto@kernel.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
kvm@vger.kernel.org, "Jason A. Donenfeld" <Jason@zx2c4.com>,
"Rik van Riel" <riel@surriel.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>
Subject: Re: [PATCH] x86/fpu: Disable BH while while loading FPU registers in __fpu__restore_sig()
Date: Mon, 19 Nov 2018 12:41:51 +0100 [thread overview]
Message-ID: <20181119114151.e4mbs7ktfjojl3uf@linutronix.de> (raw)
In-Reply-To: <433cec57-57a9-afff-22f3-68308eda682b@intel.com>
On 2018-11-12 09:48:08 [-0800], Dave Hansen wrote:
> On 11/12/18 7:56 AM, Sebastian Andrzej Siewior wrote:
> > Use local_bh_disable() around the restore sequence to avoid the race. BH
> > needs to be disabled because BH is allowed to run (even with preemption
> > disabled) and might invoke kernel_fpu_begin().
>
> FWIW, that would make nice comment fodder for the local_bh_disable().
> I'd much rather run into it there than in a changelog.
Hmm. Should I really resent a v2 of this with the additional comment?
This patch should go stable to the fix the bug and at the end of this
series I remove/replace this hunk anyway.
I can do either way, just wanted to check first.
Sebastian
next prev parent reply other threads:[~2018-11-19 11:42 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-07 19:48 [PATCH v4] x86: load FPU registers on return to userland Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 01/23] x86/fpu: Use ULL for shift in xfeature_uncompacted_offset() Sebastian Andrzej Siewior
2018-11-08 11:38 ` Borislav Petkov
2018-11-09 16:56 ` Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 02/23] x86/fpu: Remove fpu->initialized usage in __fpu__restore_sig() Sebastian Andrzej Siewior
2018-11-08 14:57 ` Borislav Petkov
2018-11-09 17:35 ` Sebastian Andrzej Siewior
2018-11-09 18:52 ` Borislav Petkov
2018-11-09 23:25 ` Sebastian Andrzej Siewior
2018-11-12 15:56 ` [PATCH] x86/fpu: Disable BH while while loading FPU registers " Sebastian Andrzej Siewior
2018-11-12 17:48 ` Dave Hansen
2018-11-19 11:41 ` Sebastian Andrzej Siewior [this message]
2018-11-19 15:04 ` Dave Hansen
2018-11-19 15:06 ` Sebastian Andrzej Siewior
2018-11-19 15:08 ` Dave Hansen
2018-11-19 15:19 ` Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 03/23] x86/fpu: Remove fpu__restore() Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 04/23] x86/entry/32: Remove asm/math_emu.h include Sebastian Andrzej Siewior
2018-11-08 18:45 ` Andy Lutomirski
2018-11-07 19:48 ` [PATCH 05/23] x86/fpu: Remove preempt_disable() in fpu__clear() Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 06/23] x86/fpu: Always init the `state' " Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 07/23] x86/fpu: Remove fpu->initialized usage in copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 08/23] x86/fpu: Remove fpu->initialized Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 09/23] x86/fpu: Remove user_fpu_begin() Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 10/23] x86/entry: Remove _TIF_ALLWORK_MASK Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 11/23] x86/fpu: Add (__)make_fpregs_active helpers Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 12/23] x86/fpu: Make __raw_xsave_addr() use feature number instead of mask Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 13/23] x86/fpu: Make get_xsave_field_ptr() and get_xsave_addr() " Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 14/23] x86/pkeys: Make init_pkru_value static Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 15/23] x86/fpu: Only write PKRU if it is different from current Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 16/23] x86/pkeys: Don't check if PKRU is zero before writting it Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 17/23] x86/fpu: Eager switch PKRU state Sebastian Andrzej Siewior
2018-11-08 11:12 ` Paolo Bonzini
2018-11-19 18:17 ` Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 18/23] x86/entry: Add TIF_NEED_FPU_LOAD Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 19/23] x86/fpu: Always store the registers in copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 20/23] x86/fpu: Prepare copy_fpstate_to_sigframe() for TIF_NEED_FPU_LOAD Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 21/23] x86/fpu: Update xstate's PKRU value on write_pkru() Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 22/23] x86/fpu: Don't restore the FPU state directly from userland in __fpu__restore_sig() Sebastian Andrzej Siewior
2018-11-08 18:25 ` Andy Lutomirski
2018-11-09 19:09 ` Sebastian Andrzej Siewior
2018-11-07 19:48 ` [PATCH 23/23] x86/fpu: Defer FPU state load until return to userspace Sebastian Andrzej Siewior
2018-11-08 8:33 ` Sebastian Andrzej Siewior
2018-11-12 3:02 ` [PATCH v4] x86: load FPU registers on return to userland Wanpeng Li
2018-11-12 3:26 ` Jason A. Donenfeld
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