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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 27D6DC432BE for ; Sat, 7 Aug 2021 07:11:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 084A860E53 for ; Sat, 7 Aug 2021 07:11:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231487AbhHGHL7 (ORCPT ); Sat, 7 Aug 2021 03:11:59 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:7805 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231326AbhHGHLz (ORCPT ); Sat, 7 Aug 2021 03:11:55 -0400 Received: from dggeme758-chm.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4GhYRd1sF5zYdSk; Sat, 7 Aug 2021 15:11:25 +0800 (CST) Received: from [10.67.103.235] (10.67.103.235) by dggeme758-chm.china.huawei.com (10.3.19.104) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Sat, 7 Aug 2021 15:11:34 +0800 Subject: Re: [PATCH V7 9/9] PCI/P2PDMA: Add a 10-Bit Tag check in P2PDMA To: Bjorn Helgaas References: <20210805181233.GA1765293@bjorn-Precision-5520> CC: , , , , , , , , From: Dongdong Liu Message-ID: <11f98331-cc39-ee37-85f7-185fdd1ccea5@huawei.com> Date: Sat, 7 Aug 2021 15:11:34 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20210805181233.GA1765293@bjorn-Precision-5520> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.103.235] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggeme758-chm.china.huawei.com (10.3.19.104) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2021/8/6 2:12, Bjorn Helgaas wrote: > On Wed, Aug 04, 2021 at 09:47:08PM +0800, Dongdong Liu wrote: >> Add a 10-Bit Tag check in the P2PDMA code to ensure that a device with >> 10-Bit Tag Requester doesn't interact with a device that does not >> support 10-BIT Tag Completer. Before that happens, the kernel should >> emit a warning. "echo 0 > /sys/bus/pci/devices/.../10bit_tag" to >> disable 10-BIT Tag Requester for PF device. >> "echo 0 > /sys/bus/pci/devices/.../sriov_vf_10bit_tag_ctl" to disable >> 10-BIT Tag Requester for VF device. > > s/10-BIT/10-Bit/ several times. Will fix. > > Add blank lines between paragraphs. Will fix. > >> Signed-off-by: Dongdong Liu >> --- >> drivers/pci/p2pdma.c | 40 ++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 40 insertions(+) >> >> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c >> index 50cdde3..948f2be 100644 >> --- a/drivers/pci/p2pdma.c >> +++ b/drivers/pci/p2pdma.c >> @@ -19,6 +19,7 @@ >> #include >> #include >> #include >> +#include "pci.h" >> >> enum pci_p2pdma_map_type { >> PCI_P2PDMA_MAP_UNKNOWN = 0, >> @@ -410,6 +411,41 @@ static unsigned long map_types_idx(struct pci_dev *client) >> (client->bus->number << 8) | client->devfn; >> } >> >> +static bool check_10bit_tags_vaild(struct pci_dev *a, struct pci_dev *b, > > s/vaild/valid/ > > Or maybe s/valid/safe/ or s/valid/supported/, since "valid" isn't > quite the right word here. We want to know whether the source is > enabled to generate 10-bit tags, and if so, whether the destination > can handle them. > > "if (check_10bit_tags_valid())" does not make sense because > "check_10bit_tags_valid()" is not a question with a yes/no answer. > > "10bit_tags_valid()" *might* be, because "if (10bit_tags_valid())" > makes sense. But I don't think you can start with a digit. > > Or maybe you want to invert the sense, e.g., > "10bit_tags_unsupported()", since that avoids negation at the caller: > > if (10bit_tags_unsupported(a, b) || > 10bit_tags_unsupported(b, a)) > map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED; Good suggestion. add a pci_ prefix. if (pci_10bit_tags_unsupported(a, b) || pci_10bit_tags_unsupported(b, a)) map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED; > Doesn't this patch need to be at the very beginning, before you start > enabling 10-bit tags? Otherwise there's a hole in the middle where we > enable them and P2P DMA might break. Yes, will do. > >> + bool verbose) >> +{ >> + bool req; >> + bool comp; >> + u16 ctl2; >> + >> + if (a->is_virtfn) { >> +#ifdef CONFIG_PCI_IOV >> + req = !!(a->physfn->sriov->ctrl & >> + PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN); >> +#endif >> + } else { >> + pcie_capability_read_word(a, PCI_EXP_DEVCTL2, &ctl2); >> + req = !!(ctl2 & PCI_EXP_DEVCTL2_10BIT_TAG_REQ_EN); >> + } >> + >> + comp = !!(b->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_COMP); >> + if (req && (!comp)) { >> + if (verbose) { >> + pci_warn(a, "cannot be used for peer-to-peer DMA as 10-Bit Tag Requester enable is set in device (%s), but peer device (%s) does not support the 10-Bit Tag Completer\n", >> + pci_name(a), pci_name(b)); > > No point in printing pci_name(a) twice. pci_warn() prints it already; > that should be enough. Will fix. > > I think you can simplify this a little, e.g., > > if (!req) /* 10-bit tags not enabled on requester */ > return true; > > if (comp) /* completer can handle anything */ > return true; > > /* error case */ > if (!verbose) > return false; > > pci_warn(...); > return false; Good point, this will make code more clean and readable. Thanks, Dongdong > >> + if (a->is_virtfn) >> + pci_warn(a, "to disable 10-Bit Tag Requester for this device, echo 0 > /sys/bus/pci/devices/%s/sriov_vf_10bit_tag_ctl\n", >> + pci_name(a)); >> + else >> + pci_warn(a, "to disable 10-Bit Tag Requester for this device, echo 0 > /sys/bus/pci/devices/%s/10bit_tag\n", >> + pci_name(a)); >> + } >> + return false; >> + } >> + >> + return true; >> +} >> + >> /* >> * Calculate the P2PDMA mapping type and distance between two PCI devices. >> * >> @@ -532,6 +568,10 @@ calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client, >> map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED; >> } >> done: >> + if (!check_10bit_tags_vaild(client, provider, verbose) || >> + !check_10bit_tags_vaild(provider, client, verbose)) >> + map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED; >> + >> rcu_read_lock(); >> p2pdma = rcu_dereference(provider->p2pdma); >> if (p2pdma) >> -- >> 2.7.4 >> > . >