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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57680 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kNLqn-0006Y1-U3 for qemu-devel@archiver.kernel.org; Tue, 29 Sep 2020 16:03:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52280) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kNLYi-0000QO-Fu for qemu-devel@nongnu.org; Tue, 29 Sep 2020 15:45:08 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:35891) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kNLYg-0007Gv-4C for qemu-devel@nongnu.org; Tue, 29 Sep 2020 15:45:08 -0400 Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1601408704; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ApZGxpY8y8F7xmMMII2LWwpwh5Cnnxx2AjaMg3GtiCI=; b=bLVu7BnXEA+KxLJzNqWDuQnrtGiI5TndZ6wCBwAbODjA4e+QEwST7qd431DFExRIoq8z4V wcFYEoNXIu32wlJi4dxlqS5dIMXxvtBncJRU8WxA8rl6AjHEaV7dmgkrmCdvE88ie/pG8w xO7Hk7L9/r49JnEwQMAbHh16juj6d90= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-140-wweYFVZrOKye_q78H9BtWg-1; Tue, 29 Sep 2020 15:45:00 -0400 X-MC-Unique: wweYFVZrOKye_q78H9BtWg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 93FCB186841B; Tue, 29 Sep 2020 19:44:59 +0000 (UTC) Received: from [10.36.113.210] (ovpn-113-210.ams2.redhat.com [10.36.113.210]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 33D7655795; Tue, 29 Sep 2020 19:44:50 +0000 (UTC) Subject: Re: [PATCH v2 2/2] util/vfio-helpers: Rework the IOVA allocator to avoid IOVA reserved regions To: Stefan Hajnoczi References: <20200929085550.30926-1-eric.auger@redhat.com> <20200929085550.30926-3-eric.auger@redhat.com> <20200929155951.GB191675@stefanha-x1.localdomain> From: Auger Eric Message-ID: <6ebdb1f7-792b-6fbe-d4b3-f06aafc8deef@redhat.com> Date: Tue, 29 Sep 2020 21:44:48 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200929155951.GB191675@stefanha-x1.localdomain> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eric.auger@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/28 22:47:55 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.687, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, lvivier@redhat.com, cohuck@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, alex.williamson@redhat.com, qemu-arm@nongnu.org, kwolf@redhat.com, philmd@redhat.com, eric.auger.pro@gmail.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Stefan, On 9/29/20 5:59 PM, Stefan Hajnoczi wrote: > On Tue, Sep 29, 2020 at 10:55:50AM +0200, Eric Auger wrote: >> diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c >> index ba0ee6e21c..71145970f3 100644 >> --- a/util/vfio-helpers.c >> +++ b/util/vfio-helpers.c >> @@ -667,6 +667,50 @@ static bool qemu_vfio_verify_mappings(QEMUVFIOState *s) >> return true; >> } >> >> +static int >> +qemu_vfio_find_fixed_iova(QEMUVFIOState *s, size_t size, uint64_t *iova) >> +{ >> + int i; >> + >> + for (i = 0; i < s->nb_iova_ranges; i++) { >> + if (s->usable_iova_ranges[i].end < s->low_water_mark) { >> + continue; >> + } >> + s->low_water_mark = >> + MAX(s->low_water_mark, s->usable_iova_ranges[i].start); >> + >> + if (s->usable_iova_ranges[i].end - s->low_water_mark + 1 >= size || >> + s->usable_iova_ranges[i].end - s->low_water_mark + 1 == 0) { > > I don't understand the == 0 case. It seems like we are allocating an > IOVA beyond usable_iova_ranges[i].end?> It is meant to handle the case were low_water_mark = 0 and s->usable_iova_ranges[0].end = ULLONG_MAX (I know it cannot exist at the moment but may happen in the future) where we get an overflow. Given the if (s->usable_iova_ranges[i].end < s->low_water_mark) { continue; } I think this prevents us from allocating beyond usable_iova_ranges[i].end or do I miss something? Thanks Eric