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,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 60AAFC433ED for ; Wed, 28 Apr 2021 08:59:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16FE461407 for ; Wed, 28 Apr 2021 08:59:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237868AbhD1JAP (ORCPT ); Wed, 28 Apr 2021 05:00:15 -0400 Received: from mga04.intel.com ([192.55.52.120]:10439 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230191AbhD1JAO (ORCPT ); Wed, 28 Apr 2021 05:00:14 -0400 IronPort-SDR: L+MS+lYa6iXp1Eu4UQpRvwQRZZ0LKlKdZahTEW+O7KcF5V9dbC8AqqSJKUcbyhfuVS+zgz0dGo kNf3sX36YEEg== X-IronPort-AV: E=McAfee;i="6200,9189,9967"; a="194578168" X-IronPort-AV: E=Sophos;i="5.82,257,1613462400"; d="scan'208";a="194578168" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2021 01:59:30 -0700 IronPort-SDR: /bV5FFoRO+Z6/L7jzTEagZTchp/QERVU7eUnbaEtz1zq57djeZbukmJh51NuYDFnfJDkg6smLI ikoeMdXuf1KQ== X-IronPort-AV: E=Sophos;i="5.82,257,1613462400"; d="scan'208";a="423434858" Received: from lingshan-mobl5.ccr.corp.intel.com (HELO [10.254.209.93]) ([10.254.209.93]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2021 01:59:28 -0700 Subject: Re: [PATCH 2/2] vDPA/ifcvf: implement doorbell mapping for ifcvf To: Jason Wang , mst@redhat.com Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210428082133.6766-1-lingshan.zhu@intel.com> <20210428082133.6766-3-lingshan.zhu@intel.com> From: "Zhu, Lingshan" Message-ID: <5052fced-cd9a-e453-5cb2-39cdde60a208@intel.com> Date: Wed, 28 Apr 2021 16:59:26 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 4/28/2021 4:42 PM, Jason Wang wrote: > > 在 2021/4/28 下午4:21, Zhu Lingshan 写道: >> This commit implements doorbell mapping feature for ifcvf. >> This feature maps the notify page to userspace, to eliminate >> vmexit when kick a vq. >> >> Signed-off-by: Zhu Lingshan >> --- >>   drivers/vdpa/ifcvf/ifcvf_main.c | 18 ++++++++++++++++++ >>   1 file changed, 18 insertions(+) >> >> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c >> b/drivers/vdpa/ifcvf/ifcvf_main.c >> index e48e6b74fe2e..afcb71bc0f51 100644 >> --- a/drivers/vdpa/ifcvf/ifcvf_main.c >> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c >> @@ -413,6 +413,23 @@ static int ifcvf_vdpa_get_vq_irq(struct >> vdpa_device *vdpa_dev, >>       return vf->vring[qid].irq; >>   } >>   +static struct vdpa_notification_area >> ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev, >> +                                   u16 idx) >> +{ >> +    struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev); >> +    struct vdpa_notification_area area; >> + >> +    if (vf->notify_pa % PAGE_SIZE) { >> +        area.addr = 0; >> +        area.size = 0; > > > We don't need this since: > > 1) there's a check in the vhost vDPA I think you mean this code block in vdpa.c         notify = ops->get_vq_notification(vdpa, index);         if (notify.addr & (PAGE_SIZE - 1))                 return -EINVAL; This should work, however, I think the parent driver should ensure it passes a PAGE_SIZE aligned address to userspace, to be robust, to be reliable. > 2) device is unaware of the bound driver, non page aligned doorbell > doesn't necessarily meant it can be used Yes, non page aligned doorbell can not be used, so there is a check. Thanks Zhu Lingshan > > Let's leave those polices to the driver. > > Thanks > > >> +    } else { >> +        area.addr = vf->notify_pa; >> +        area.size = PAGE_SIZE; >> +    } >> + >> +    return area; >> +} >> + >>   /* >>    * IFCVF currently does't have on-chip IOMMU, so not >>    * implemented set_map()/dma_map()/dma_unmap() >> @@ -440,6 +457,7 @@ static const struct vdpa_config_ops ifc_vdpa_ops = { >>       .get_config    = ifcvf_vdpa_get_config, >>       .set_config    = ifcvf_vdpa_set_config, >>       .set_config_cb  = ifcvf_vdpa_set_config_cb, >> +    .get_vq_notification = ifcvf_get_vq_notification, >>   }; >>     static int ifcvf_probe(struct pci_dev *pdev, const struct >> pci_device_id *id) >