From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E9B4C4361B for ; Tue, 8 Dec 2020 17:44:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3794023B44 for ; Tue, 8 Dec 2020 17:44:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730824AbgLHRoa (ORCPT ); Tue, 8 Dec 2020 12:44:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:37234 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726810AbgLHRoa (ORCPT ); Tue, 8 Dec 2020 12:44:30 -0500 Date: Tue, 8 Dec 2020 19:43:44 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607449429; bh=4jaDJ4cW63InYyAcO+7Mk8fItHOLvl2IgoGj31CddDo=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=Kjwf8bc9wBpKUStdt/Oyw4IP3gAG4BibCF9WYfQgVPv+530xR3xCu2Guf/wEDpTZv odhZaT7q1+aavhFe4b2TwB68KYqEcC1kF2y9aUSB5cXcJiD941XmhB0McgOaLPIEJZ W6EZWxrOQyyvxUrb5Mf1z7g3bFls0bNk46P43gtUy1NO6N+uFlxU64F95VY7/6AWyG OWgWWRXFITVRhgvY37HEXXKb0NHWftCC9dIlynHB6m10QZ3d/yFn87P6/tvsnbzcv+ 57bNV7FET+rx6QNmQmTuf5rn0vCg/xB205fxkg3kHIYDsPhCRE+KLbVn//7RPnEhKi ZsEcFzQdWFaPA== From: Jarkko Sakkinen To: James Bottomley Cc: Jason Gunthorpe , Thomas Gleixner , Jerry Snitselaar , linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Peter Huewe , Matthew Garrett , Hans de Goede Subject: Re: [PATCH v3 3/4] tpm_tis: Disable interrupts if interrupt storm detected Message-ID: <20201208174344.GC58213@kernel.org> References: <20201205014340.148235-1-jsnitsel@redhat.com> <20201205014340.148235-4-jsnitsel@redhat.com> <87tusy7n3b.fsf@nanos.tec.linutronix.de> <20201207192803.GH5487@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 07, 2020 at 11:58:44AM -0800, James Bottomley wrote: > On Mon, 2020-12-07 at 15:28 -0400, Jason Gunthorpe wrote: > > On Sun, Dec 06, 2020 at 08:26:16PM +0100, Thomas Gleixner wrote: > > > Just as a side note. I was looking at tpm_tis_probe_irq_single() > > > and that function is leaking the interrupt request if any of the > > > checks afterwards fails, except for the final interrupt probe check > > > which does a cleanup. That means on fail before that the interrupt > > > handler stays requested up to the point where the module is > > > removed. If that's a shared interrupt and some other device is > > > active on the same line, then each interrupt from that device will > > > call into the TPM code. Something like the below is needed. > > > > > > Also the X86 autoprobe mechanism is interesting: > > > > > > if (IS_ENABLED(CONFIG_X86)) > > > for (i = 3; i <= 15; i++) > > > if (!tpm_tis_probe_irq_single(chip, intmask, 0, > > > i)) > > > return; > > > > > > The third argument is 'flags' which is handed to request_irq(). So > > > that won't ever be able to probe a shared interrupt. But if an > > > interrupt number > 0 is handed to tpm_tis_core_init() the interrupt > > > is requested with IRQF_SHARED. Same issue when the chip has an > > > interrupt number in the register. It's also requested exclusive > > > which is pretty likely to fail on ancient x86 machines. > > > > It is very likely none of this works any more, it has been repeatedly > > reworked over the years and just left behind out of fear someone > > needs it. I've thought it should be deleted for a while now. > > > > I suppose the original logic was to try and probe without SHARED > > because a probe would need exclusive access to the interrupt to tell > > if the TPM was actually the source, not some other device. > > > > It is all very old and very out of step with current thinking, IMHO. > > I skeptical that TPM interrupts were ever valuable enough to deserve > > this in the first place. > > For what it's worth, I agree. Trying to probe all 15 ISA interrupts is > last millennium thinking we should completely avoid. If it's not > described in ACPI then you don't get an interrupt full stop. > > James Maybe you could add this as part of your patches? /Jarkko