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[23.128.96.18]) by mx.google.com with ESMTP id j7si2125319ejm.492.2021.09.15.18.15.06; Wed, 15 Sep 2021 18:15:30 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=bwVgtzzG; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233602AbhIPBMx (ORCPT + 99 others); Wed, 15 Sep 2021 21:12:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:44275 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231335AbhIPBMx (ORCPT ); Wed, 15 Sep 2021 21:12:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631754693; 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: in-reply-to:in-reply-to:references:references; bh=74EoAWXmDLcPB3Fwyw9DAw7gIYO7nWQCSI4r7V+M3G4=; b=bwVgtzzGhYIOfVt39zH7eNUsm9vc68P/Edyq/QUUiUEDLGxyFirqcWSKSrlT/rqLNWRdZ+ g52jQ2Szr5gv2GOCihucFhTjpoi9PrFEwu7a+gZiCJDSc2HjK3A2WjaDgP1OaZJNjkP5/Z nmd9n17zKp1uCc9LcEy+krUBuemzNc0= Received: from mail-lf1-f70.google.com (mail-lf1-f70.google.com [209.85.167.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-171-n56PSBDTM2mguvxBCs-crA-1; Wed, 15 Sep 2021 21:11:32 -0400 X-MC-Unique: n56PSBDTM2mguvxBCs-crA-1 Received: by mail-lf1-f70.google.com with SMTP id v19-20020a056512349300b003f72647edb4so2380525lfr.6 for ; Wed, 15 Sep 2021 18:11:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=74EoAWXmDLcPB3Fwyw9DAw7gIYO7nWQCSI4r7V+M3G4=; b=WXTw5eJWJuopEnY1k5Lf83l+PYUzDmgj7alvWMtz24JGgROEFVhvHEBngmOOnCaGmw 3Bxhf8uSISc8OYCkS8EMtBmIJtqjNSzoMCMRso+kq1CuhTT6aJ5TC5yEz3W7uZl5qTC5 V1+sLhzymjPmj10rOZcB8yrRIGg2BGJ6DUEVD3Ov2PwdRENfzlo0pDWrzcD3Op9jyTOr EG+8cwzonlMQiWInYq5FzwN/067RMm2w6UAHvJGZsZdrvXKzy/kYw8Cfiy/qI0guGhUv q27ypFOXGSsX0SAVNV54S7SMY48vU8bRH6dWXFIfxxGCIfSXuba7vLrau40bU5q8wS1a UyAw== X-Gm-Message-State: AOAM532cQQS9UhpblRsnMIpGZJavt+40ylMnj5c3oWDZffRODIf2jzXn 6pc8ye/OssNX16JA+SZslPok/75QtiK/uhdkwekTfbcLoz0S4If0gdqyYQCDx/9/4Dh88Rz1QQV l/4Ivo97B6E6RB1MD/ZcLsqSSmdDrnQoDMe0342qF X-Received: by 2002:a05:6512:32ca:: with SMTP id f10mr2106908lfg.498.1631754690412; Wed, 15 Sep 2021 18:11:30 -0700 (PDT) X-Received: by 2002:a05:6512:32ca:: with SMTP id f10mr2106898lfg.498.1631754690171; Wed, 15 Sep 2021 18:11:30 -0700 (PDT) MIME-Version: 1.0 References: <834528d24c839080215b2e077f100e9ed5073edc.1631621507.git.wuzongyong@linux.alibaba.com> <20210914085711-mutt-send-email-mst@kernel.org> <20210915033756-mutt-send-email-mst@kernel.org> <20210915070805-mutt-send-email-mst@kernel.org> <20210915121234.GA19232@L-PF27918B-1352.localdomain> In-Reply-To: <20210915121234.GA19232@L-PF27918B-1352.localdomain> From: Jason Wang Date: Thu, 16 Sep 2021 09:11:19 +0800 Message-ID: Subject: Re: [PATCH v2 4/5] vdpa: add new vdpa attribute VDPA_ATTR_DEV_F_VERSION_1 To: Wu Zongyong Cc: "Michael S. Tsirkin" , virtualization , linux-kernel , wei.yang1@linux.alibaba.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 15, 2021 at 8:12 PM Wu Zongyong wrote: > > On Wed, Sep 15, 2021 at 07:08:51AM -0400, Michael S. Tsirkin wrote: > > On Wed, Sep 15, 2021 at 04:06:57PM +0800, Jason Wang wrote: > > > On Wed, Sep 15, 2021 at 3:38 PM Michael S. Tsirkin wrote: > > > > > > > > On Wed, Sep 15, 2021 at 11:18:06AM +0800, Jason Wang wrote: > > > > > On Tue, Sep 14, 2021 at 8:58 PM Michael S. Tsirkin wrote: > > > > > > > > > > > > On Tue, Sep 14, 2021 at 08:24:51PM +0800, Wu Zongyong wrote: > > > > > > > This new attribute advertises whether the vdpa device is legacy or not. > > > > > > > Users can pick right virtqueue size if the vdpa device is legacy which > > > > > > > doesn't support to change virtqueue size. > > > > > > > > > > > > > > Signed-off-by: Wu Zongyong > > > > > > > > > > > > So if we are bothering with legacy, > > > > > > > > > > I think we'd better not. I guess the following may work: > > > > > > > > > > 1) disable the driver on BE host > > > > > 2) present VERSION_1 with ACCESS_PLATFORM in get_features() > > > > > 3) extend the management to advertise max_queue_size and > > > > > min_queue_size, for ENI they are the same so management layer knows it > > > > > needs to set the queue_size correctly during launching qemu > > > > > > > > > > Thoughts? > > > > > > > > > > Thanks > > > > > > > > There are other subtle differences such as header size without > > > > mergeable buffers for net. > > > > > > This can be solved by mandating the feature of a mergeable buffer? > > > > > > Thanks > > > > PXE and some dpdk versions are only some of the guests that > > disable mergeable buffers feature. > > > So what about this: > > 1) disable the driver on BE host > AFAIK, there are no use cases for ENI to be used in a BE machine. So > just disable the driver on BE machine, it will make things simper. > 2) present ACCESS_PLATFORM but not VERSION_1 in get_features() This sounds like a violation of the virtio spec. ACCESS_PLATFORM depends on VERSION_1. > 3) extend the management to advertise min_queue_size > min_queue_size is the same as with max_queue_size for ENI. > > Another choice for 3): > extend the management to advertise the flag F_VERSION_1 just like > this patch This will bring a lot of trouble, notice that the legacy/transitional device doesn't work in several layers (both vdpa kernel and qemu). If we can afford mandating mergeable rx buffers in the driver, it's the most simple way. I guess you should have the plan for the next generation ENI which should support VERSION_1 and RING_PACKED. Thanks > > > > > > > > > > > > > > I think there are > > > > > > several things to do when building the interface > > > > > > - support transitional devices, that is allow userspace > > > > > > to tell device it's in legacy mode > > > > > > - support reporting/setting supporting endian-ness > > > > > > > > > > > > > --- > > > > > > > drivers/vdpa/vdpa.c | 6 ++++++ > > > > > > > drivers/virtio/virtio_vdpa.c | 7 ++++++- > > > > > > > include/uapi/linux/vdpa.h | 1 + > > > > > > > 3 files changed, 13 insertions(+), 1 deletion(-) > > > > > > > > > > > > > > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c > > > > > > > index 1dc121a07a93..533d7f589eee 100644 > > > > > > > --- a/drivers/vdpa/vdpa.c > > > > > > > +++ b/drivers/vdpa/vdpa.c > > > > > > > @@ -12,6 +12,7 @@ > > > > > > > #include > > > > > > > #include > > > > > > > #include > > > > > > > +#include > > > > > > > #include > > > > > > > #include > > > > > > > > > > > > > > @@ -494,6 +495,7 @@ vdpa_dev_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq > > > > > > > u16 max_vq_size; > > > > > > > u32 device_id; > > > > > > > u32 vendor_id; > > > > > > > + u64 features; > > > > > > > void *hdr; > > > > > > > int err; > > > > > > > > > > > > > > @@ -508,6 +510,7 @@ vdpa_dev_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq > > > > > > > device_id = vdev->config->get_device_id(vdev); > > > > > > > vendor_id = vdev->config->get_vendor_id(vdev); > > > > > > > max_vq_size = vdev->config->get_vq_num_max(vdev); > > > > > > > + features = vdev->config->get_features(vdev); > > > > > > > > > > > > > > err = -EMSGSIZE; > > > > > > > if (nla_put_string(msg, VDPA_ATTR_DEV_NAME, dev_name(&vdev->dev))) > > > > > > > @@ -520,6 +523,9 @@ vdpa_dev_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq > > > > > > > goto msg_err; > > > > > > > if (nla_put_u16(msg, VDPA_ATTR_DEV_MAX_VQ_SIZE, max_vq_size)) > > > > > > > goto msg_err; > > > > > > > + if (features & BIT_ULL(VIRTIO_F_VERSION_1) && > > > > > > > + nla_put_flag(msg, VDPA_ATTR_DEV_VERSION_1)) > > > > > > > + goto msg_err; > > > > > > > > > > > > > > genlmsg_end(msg, hdr); > > > > > > > return 0; > > > > > > > diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c > > > > > > > index 72eaef2caeb1..1cba957c4cdc 100644 > > > > > > > --- a/drivers/virtio/virtio_vdpa.c > > > > > > > +++ b/drivers/virtio/virtio_vdpa.c > > > > > > > @@ -7,6 +7,7 @@ > > > > > > > * > > > > > > > */ > > > > > > > > > > > > > > +#include "linux/virtio_config.h" > > > > > > > #include > > > > > > > #include > > > > > > > #include > > > > > > > @@ -145,6 +146,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index, > > > > > > > /* Assume split virtqueue, switch to packed if necessary */ > > > > > > > struct vdpa_vq_state state = {0}; > > > > > > > unsigned long flags; > > > > > > > + bool may_reduce_num = false; > > > > > > > u32 align, num; > > > > > > > int err; > > > > > > > > > > > > > > @@ -169,10 +171,13 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index, > > > > > > > goto error_new_virtqueue; > > > > > > > } > > > > > > > > > > > > > > + if (ops->get_features(vdpa) & BIT_ULL(VIRTIO_F_VERSION_1)) > > > > > > > + may_reduce_num = true; > > > > > > > + > > > > > > > /* Create the vring */ > > > > > > > align = ops->get_vq_align(vdpa); > > > > > > > vq = vring_create_virtqueue(index, num, align, vdev, > > > > > > > - true, true, ctx, > > > > > > > + true, may_reduce_num, ctx, > > > > > > > virtio_vdpa_notify, callback, name); > > > > > > > if (!vq) { > > > > > > > err = -ENOMEM; > > > > > > > diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h > > > > > > > index 66a41e4ec163..ce0b74276a5b 100644 > > > > > > > --- a/include/uapi/linux/vdpa.h > > > > > > > +++ b/include/uapi/linux/vdpa.h > > > > > > > @@ -32,6 +32,7 @@ enum vdpa_attr { > > > > > > > VDPA_ATTR_DEV_VENDOR_ID, /* u32 */ > > > > > > > VDPA_ATTR_DEV_MAX_VQS, /* u32 */ > > > > > > > VDPA_ATTR_DEV_MAX_VQ_SIZE, /* u16 */ > > > > > > > + VDPA_ATTR_DEV_VERSION_1, /* flag */ > > > > > > > > > > > > > > /* new attributes must be added above here */ > > > > > > > VDPA_ATTR_MAX, > > > > > > > -- > > > > > > > 2.31.1 > > > > > > > > > > >