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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34D49C433F5 for ; Wed, 30 Mar 2022 15:17:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348088AbiC3PTL (ORCPT ); Wed, 30 Mar 2022 11:19:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348229AbiC3PSw (ORCPT ); Wed, 30 Mar 2022 11:18:52 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96CFF15282F; Wed, 30 Mar 2022 08:17:05 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 4BA13B81B2F; Wed, 30 Mar 2022 15:17:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5162DC340EE; Wed, 30 Mar 2022 15:17:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648653423; bh=u2jR/AODUADFu7Jvj8F3udIhitEKoWuiVbotMtsdjZs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tcE7B86EEgq0AXr8xciTdsqSMhDD0atGPgD2K1pgNdDbr04q3R1psgAFvGIoOkYlw OMG50Q+MwKVxawsSOWEQwateeCigV6G68saMpMUH+EceUbschdTnfEwg3UojvbLBpe 0dTMu7CqKNJcAfuri3W0BDjAkp4JLtPBZnMPO7Q6LSkN9OzEo8cjuI7CdCnta++I37 uhLuBHbEkQaqyGmtg1donjJV/ZLwQHXhERcEAjdEMsdqyjSywPYGYzpGB/0lJQWohP he04cmeyoZg1qwd9qLKmbHacX7VW50yXyAQIDwgQAqwPMLu5EH8wPOBAJau2r63Yi+ ZID4HoM7MdcuA== Date: Wed, 30 Mar 2022 18:18:09 +0300 From: Jarkko Sakkinen To: Michael =?iso-8859-1?Q?Niew=F6hner?= Cc: Lino Sanfilippo , peterhuewe@gmx.de, jgg@ziepe.ca, stefanb@linux.vnet.ibm.com, stefanb@linux.ibm.com, James.Bottomley@hansenpartnership.com, keescook@chromium.org, jsnitsel@redhat.com, ml.linux@elloe.vision, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, twawrzynczak@chromium.org Subject: Re: [PATCH v3 0/4] Fixes for TPM interrupt handling Message-ID: References: <20210501135727.17747-1-LinoSanfilippo@gmx.de> <20210501135727.17747-3-LinoSanfilippo@gmx.de> <6722bf6f-1a3f-ee9c-55e2-cf63c64266a9@gmx.de> <2a1a1cf61732eff1608aeae74054a0c135c1671f.camel@mniewoehner.de> <0d6c22b40a2f17d4b260f287d4c479a96a88b0b1.camel@mniewoehner.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <0d6c22b40a2f17d4b260f287d4c479a96a88b0b1.camel@mniewoehner.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 25, 2022 at 01:32:25PM +0100, Michael Niewöhner wrote: > On Fri, 2022-03-25 at 04:14 +0200, Jarkko Sakkinen wrote: > > On Thu, Mar 24, 2022 at 06:04:23PM +0100, Michael Niewöhner wrote: > > > Hi guys, > > > > > > On Thu, 2021-05-06 at 04:47 +0300, Jarkko Sakkinen wrote: > > > > On Wed, May 05, 2021 at 01:15:29AM +0200, Lino Sanfilippo wrote: > > > > > Hi, > > > > > > > > > > On 03.05.21 at 17:50, Jarkko Sakkinen wrote: > > > > > > What the heck is "simplification" and what that has to do with fixing > > > > > > anything? I don't understand your terminology. > > > > > > > > > > > > > > > The intention for this patch is not to fix anything. Please read the > > > > > cover > > > > > letter and the commit message. > > > > > This patch is about making the locality handling easier by not > > > > > claiming/releasing > > > > > it multiple times over the driver life time, but claiming it once at > > > > > driver > > > > > startup and only releasing it at driver shutdown. > > > > > > > > > > Right now we have locality request/release combos in > > > > > > > > > > - probe_itpm() > > > > > - tpm_tis_gen_interrupt() > > > > > - tpm_tis_core_init() > > > > > - tpm_chip_start() > > > > > > > > > > and there is still one combo missing for > > > > > > > > > > - tpm2_get_timeouts() > > > > > > > > > > which is the reason why we get the "TPM returned invalid status" bug in > > > > > case > > > > > of TPM2 (and this is the bug which is _incidentally_ fixed by this > > > > > patch, > > > > > see > > > > > below). > > > > > > > > > > And if we are going to enable interrupts, we have to introduce yet > > > > > another > > > > > combo, > > > > > for accessing the status register in the interrupt handler, since TPM > > > > > 2.0 > > > > > requires holding the locality for writing to the status register. That > > > > > makes > > > > > 6 different code places in which we take and release the locality. > > > > > > > > > > With this patch applied we only take the locality at one place. > > > > > Furthermore > > > > > with interrupts enabled we dont have to claim the locality for each > > > > > handler > > > > > execution, saving us countless claim/release combinations at runtime. > > > > > > > > > > Hence the term "simplification" which is perfectly justified IMO. > > > > > > > > > > So again, this patch is "only" in preparation for the next patch when > > > > > interrupts > > > > > are actually enabled and we would have to take the locality in the > > > > > interrupt > > > > > handler without this patch. > > > > > > > > So: what problem this patch does solve? > > > > > > > > /Jarkko > > > > > > > > > > first, thank you very much, Lino, for working on this! I've been debugging > > > issues with the tis driver in the last days and was about to start with the > > > same > > > approach as yours when I luckily discovered your patch! > > > > > > Jarkko, while I agree, that the commit message is not optimal, Lino tried > > > hard > > > to explain what the problems with the current code are and how they are / > > > can be > > > fixed. Further, I too don't see why simplification / optimization is such a > > > bad > > > thing. This driver is actually a very good example. I had a hard time, too, > > > figuring out what's going on there. A clean rewrite is a very valid approach > > > here IMO. It's not "polishing for nothing", as you described it, but > > > actually > > > solving problems. > > > > > > Interrupt detection is broken for years now and finally a volunteer worked > > > on a > > > solution. Don't you think this should be valued? Let's get this problem > > > sorted > > > out :-) > > > > > > Lino, I'd be happy to test the patches, when you have time and interest to > > > work > > > on this again! > > > > > > Thanks, Michael > > > > It's quite easy to test them out. Both fixes are in the mainline GIT tree. > > E.g. give a shot rc1, and please report if any issues persists to: > > > >   linux-integrity@vger.kernel.org  > > > > BR, Jarkko > > I don't see Linos patches on mainline. Also, the series included four patches: > [PATCH v3 0/4] Fixes for TPM interrupt handling > [PATCH v3 1/4] tpm: Use a threaded interrupt handler > [PATCH v3 2/4] tpm: Simplify locality handling > [PATCH v3 3/4] tpm: Fix test for interrupts > [PATCH v3 4/4] tpm: Only enable supported irqs > > Three of them are relevant for the interrupt problem, which is still present in > mainline, as these patches were refused: > [PATCH v3 1/4] tpm: Use a threaded interrupt handler > [PATCH v3 2/4] tpm: Simplify locality handling > [PATCH v3 3/4] tpm: Fix test for interrupts > > Michael There was some unaddressed feedback, most of not that hard to address. I'm waiting for v4. BR, Jarkko