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From: Thomas Gleixner <tglx@linutronix.de>
To: "Bae, Chang Seok" <chang.seok.bae@intel.com>
Cc: "bp@suse.de" <bp@suse.de>, "Lutomirski, Andy" <luto@kernel.org>,
	"mingo@kernel.org" <mingo@kernel.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"Brown, Len" <len.brown@intel.com>,
	"lenb@kernel.org" <lenb@kernel.org>,
	"Hansen, Dave" <dave.hansen@intel.com>,
	"Macieira, Thiago" <thiago.macieira@intel.com>,
	"Liu, Jing2" <jing2.liu@intel.com>,
	"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v10 13/28] x86/fpu/xstate: Use feature disable (XFD) to protect dynamic user state
Date: Mon, 04 Oct 2021 14:35:18 +0200	[thread overview]
Message-ID: <87bl45ge7t.ffs@tglx> (raw)
In-Reply-To: <E5C66E6E-8AB8-4258-814D-C8E94446E2C4@intel.com>

On Sun, Oct 03 2021 at 22:38, Chang Seok Bae wrote:
> On Oct 1, 2021, at 08:10, Thomas Gleixner <tglx@linutronix.de> wrote:
>> 	local_irq_enable();
>
> v1 had some similar ones (not the same though) [1]. FWIW, I think Andy’s point
> is worth to be noted here:
>
>     First, you can't just enable IRQs here. If IRQs are off, they're off for a
>     reason. Secondly, if they're *on*, you just forgot that fact.

The #NM comes from user space where interrupts are always enabled. So we
can enable interrupts _after_ doing the sanity checks.

Also we reenable interrupts in various other trap handlers when the trap
comes from user space as well. That's perfectly fine and required. How
would e.g. fault handling or single stepping ever work otherwise?

I have no idea where you had places the local_irq_enable(), but the code
I outlined is correct.

Thanks,

        tglx


  reply	other threads:[~2021-10-04 12:35 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-25 15:53 [PATCH v10 00/28] x86: Support Intel Advanced Matrix Extensions Chang S. Bae
2021-08-25 15:53 ` [PATCH v10 01/28] x86/fpu/xstate: Fix the state copy function to the XSTATE buffer Chang S. Bae
2021-10-01 12:44   ` Thomas Gleixner
2021-10-03 22:34     ` Bae, Chang Seok
2021-08-25 15:53 ` [PATCH v10 02/28] x86/fpu/xstate: Modify the initialization helper to handle both static and dynamic buffers Chang S. Bae
2021-10-01 12:45   ` Thomas Gleixner
2021-10-03 22:35     ` Bae, Chang Seok
2021-08-25 15:53 ` [PATCH v10 03/28] x86/fpu/xstate: Modify state copy helpers " Chang S. Bae
2021-10-01 12:47   ` Thomas Gleixner
2021-10-03 22:42     ` Bae, Chang Seok
2021-08-25 15:53 ` [PATCH v10 04/28] x86/fpu/xstate: Modify address finders " Chang S. Bae
2021-10-01 13:15   ` Thomas Gleixner
2021-10-03 22:35     ` Bae, Chang Seok
2021-10-04 12:54       ` Thomas Gleixner
2021-08-25 15:53 ` [PATCH v10 05/28] x86/fpu/xstate: Add a new variable to indicate dynamic user states Chang S. Bae
2021-10-01 13:16   ` Thomas Gleixner
2021-10-03 22:35     ` Bae, Chang Seok
2021-10-04 12:57       ` Thomas Gleixner
2021-08-25 15:53 ` [PATCH v10 06/28] x86/fpu/xstate: Add new variables to indicate dynamic XSTATE buffer size Chang S. Bae
2021-10-01 13:32   ` Thomas Gleixner
2021-10-03 22:36     ` Bae, Chang Seok
2021-08-25 15:53 ` [PATCH v10 07/28] x86/fpu/xstate: Calculate and remember dynamic XSTATE buffer sizes Chang S. Bae
2021-08-25 15:53 ` [PATCH v10 08/28] x86/fpu/xstate: Convert the struct fpu 'state' field to a pointer Chang S. Bae
2021-08-25 15:53 ` [PATCH v10 09/28] x86/fpu/xstate: Introduce helpers to manage the XSTATE buffer dynamically Chang S. Bae
2021-10-01 14:20   ` Thomas Gleixner
2021-10-03 22:36     ` Bae, Chang Seok
2021-08-25 15:53 ` [PATCH v10 10/28] x86/fpu/xstate: Update the XSTATE save function to support dynamic states Chang S. Bae
2021-10-01 15:41   ` Thomas Gleixner
2021-10-02 21:31     ` Thomas Gleixner
2021-10-02 22:54       ` Bae, Chang Seok
2021-10-05  8:16         ` Paolo Bonzini
2021-10-05  7:50       ` Paolo Bonzini
2021-10-05  9:55         ` Thomas Gleixner
2021-08-25 15:53 ` [PATCH v10 11/28] x86/fpu/xstate: Update the XSTATE buffer address finder " Chang S. Bae
2021-08-25 15:53 ` [PATCH v10 12/28] x86/fpu/xstate: Update the XSTATE context copy function " Chang S. Bae
2021-08-25 15:53 ` [PATCH v10 13/28] x86/fpu/xstate: Use feature disable (XFD) to protect dynamic user state Chang S. Bae
2021-10-01 15:02   ` Thomas Gleixner
2021-10-01 15:10     ` Thomas Gleixner
2021-10-03 22:38       ` Bae, Chang Seok
2021-10-04 12:35         ` Thomas Gleixner [this message]
2021-10-01 20:20     ` Thomas Gleixner
2021-10-03 22:39       ` Bae, Chang Seok
2021-10-04 19:03         ` Thomas Gleixner
2021-10-03 22:41     ` Bae, Chang Seok
2021-08-25 15:53 ` [PATCH v10 14/28] x86/fpu/xstate: Support ptracer-induced XSTATE buffer expansion Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 15/28] x86/arch_prctl: Create ARCH_SET_STATE_ENABLE/ARCH_GET_STATE_ENABLE Chang S. Bae
2021-08-25 16:36   ` Bae, Chang Seok
2021-08-25 15:54 ` [PATCH v10 16/28] x86/fpu/xstate: Support both legacy and expanded signal XSTATE size Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 17/28] x86/fpu/xstate: Adjust the XSAVE feature table to address gaps in state component numbers Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 18/28] x86/fpu/xstate: Disable XSTATE support if an inconsistent state is detected Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 19/28] x86/cpufeatures/amx: Enumerate Advanced Matrix Extension (AMX) feature bits Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 20/28] x86/fpu/amx: Define AMX state components and have it used for boot-time checks Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 21/28] x86/fpu/amx: Initialize child's AMX state Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 22/28] x86/fpu/amx: Enable the AMX feature in 64-bit mode Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 23/28] x86/fpu/xstate: Skip writing zeros to signal frame for dynamic user states if in INIT-state Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 24/28] selftest/x86/amx: Test cases for the AMX state management Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 25/28] x86/insn/amx: Add TILERELEASE instruction to the opcode map Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 26/28] intel_idle/amx: Add SPR support with XTILEDATA capability Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 27/28] x86/fpu/xstate: Add a sanity check for XFD state when saving XSTATE Chang S. Bae
2021-08-25 15:54 ` [PATCH v10 28/28] x86/arch_prctl: ARCH_GET_FEATURES_WITH_KERNEL_ASSISTANCE Chang S. Bae
2021-09-30 21:12 ` [PATCH v10 00/28] x86: Support Intel Advanced Matrix Extensions Len Brown

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