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 8D6B5C19F2B for ; Thu, 4 Aug 2022 10:59:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239256AbiHDK7K (ORCPT ); Thu, 4 Aug 2022 06:59:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231440AbiHDK7H (ORCPT ); Thu, 4 Aug 2022 06:59:07 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ECA7013E33 for ; Thu, 4 Aug 2022 03:59:05 -0700 (PDT) Received: from fraeml711-chm.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Lz5GL5vpnz67RRb; Thu, 4 Aug 2022 18:54:50 +0800 (CST) Received: from lhrpeml500003.china.huawei.com (7.191.162.67) by fraeml711-chm.china.huawei.com (10.206.15.60) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 4 Aug 2022 12:59:03 +0200 Received: from [10.195.34.58] (10.195.34.58) by lhrpeml500003.china.huawei.com (7.191.162.67) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 4 Aug 2022 11:59:03 +0100 Message-ID: <17b5e57b-326e-11c1-d8c7-87f3d3d7d0ff@huawei.com> Date: Thu, 4 Aug 2022 11:59:05 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: PCI MSI issue with reinserting a driver From: John Garry To: Marc Zyngier CC: Thomas Gleixner , Zhou Wang , , , "zhanjie (F)" References: <87o8h3lj0n.wl-maz@kernel.org> <8a54fdd0-950b-f801-e83d-750aef73ab3c@huawei.com> <4848792ce8c9ed7490e2205281a3cbda@kernel.org> <28c56995-501a-880b-e6dd-ac76b8290c2c@huawei.com> <3d3d0155e66429968cb4f6b4feeae4b3@kernel.org> In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.195.34.58] X-ClientProxiedBy: lhreml744-chm.china.huawei.com (10.201.108.194) To lhrpeml500003.china.huawei.com (7.191.162.67) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/02/2021 10:45, John Garry wrote: Hi Marc, Just a friendly reminder that we still have the issue with reinseting a PCI driver which does not allocate a power-of-2 MSIs. > On 03/02/2021 17:23, Marc Zyngier wrote: >>> >>> Before: >>>  In free path, we have: >>>      its_irq_domain_free(nvecs = 27) >>>        bitmap_release_region(count order = 5 == 32bits) >>> >>> Current: >>>  In free path, we have: >>>      its_irq_domain_free(nvecs = 1) for free each 27 vecs >>>        bitmap_release_region(count order = 0 == 1bit) >> >> Right. I was focusing on the patch and blindly ignored the explanation >> at the top of the email. Apologies for that. > > Yeah, it was a distraction. > >> >> I'm not overly keen on handling this in the ITS though, and I'd rather >> we try and do it in the generic code. How about this (compile tested >> only)? >> >> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c >> index 6aacd342cd14..cfccad83c2df 100644 >> --- a/kernel/irq/irqdomain.c >> +++ b/kernel/irq/irqdomain.c >> @@ -1399,8 +1399,19 @@ static void >> irq_domain_free_irqs_hierarchy(struct irq_domain *domain, >>           return; >> >>       for (i = 0; i < nr_irqs; i++) { >> -        if (irq_domain_get_irq_data(domain, irq_base + i)) >> -            domain->ops->free(domain, irq_base + i, 1); >> +        int n ; >> + >> +        /* Find the largest possible span of IRQs to free in one go */ >> +        for (n = 0; >> +             ((i + n) < nr_irqs && >> +              irq_domain_get_irq_data(domain, irq_base + i + n)); >> +             n++); >> + >> +        if (!n) >> +            continue; >> + >> +        domain->ops->free(domain, irq_base + i, n); >> +        i += n; >>       } >>   } > > That fixed my problem. > > For my benefit, if MSIs must be allocated in power of 2, could we check > a flag for the dealloc method? Like, if MSI domain, then do as before > 4615fbc3788d. But I'm not sure on the specific scenario which that > commit fixed. Or even whether you want specifics like that in core code. Thanks, John