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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 5B9AAC433E2 for ; Mon, 29 Jun 2020 18:52:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3613220663 for ; Mon, 29 Jun 2020 18:52:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Cqh6vIk8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729450AbgF2SwQ (ORCPT ); Mon, 29 Jun 2020 14:52:16 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:35906 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726967AbgF2SwM (ORCPT ); Mon, 29 Jun 2020 14:52:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593456730; 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=3IU9n+aBPLrPIZ0eR9RIDgzyyTwxAS9aWp/34wgBsy4=; b=Cqh6vIk8Y+KsGA8cF3+BzDoedcf9S5nbfQMEshkfKNsg7JEXVY6my3vZPgDb1WQ3YWNi6S G0VCbc62SAbXkOCEKoTl0P1xXNiqFth4qtLgpnroK3WLUtbJ84nYjoifS/kVctuhYWancT loHDkVo+fsyePF79g/Xp0DEqwJBG3IA= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-86-kwjKeMo5PBe0Tpiz-ZyFBw-1; Mon, 29 Jun 2020 11:49:58 -0400 X-MC-Unique: kwjKeMo5PBe0Tpiz-ZyFBw-1 Received: by mail-wm1-f71.google.com with SMTP id o13so18563861wmh.9 for ; Mon, 29 Jun 2020 08:49:58 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=3IU9n+aBPLrPIZ0eR9RIDgzyyTwxAS9aWp/34wgBsy4=; b=FROtM0zSEyylfUBHldNV+bofepHAAr9hapFMl131OvPU35OaWpNdivF9uP/76814fQ ozuBdAyuHLEQr71bL/VffdcteZ54admo6hQU1QXu5G6TuWtq9DPNy5G12renLz1myFxC wk/SbeBWP8MyRStF2cGDPHotVdibwAExdPwD19SL/4OCEsb2kzSJLGJEhcXEQ0k2g5UO vQci+Xr+3EEh0LXwegrGg3y1TxXCQ/vyLO+/wLQQgbX780KB3/8RUUDN2lgdUg5DS0lJ iTVOWN9F4MGqwzYFD3my2Mov7LikRKRQpb87BhC8rvwcf5PxXlk8DYsz6XuN+XR9AIds O0EQ== X-Gm-Message-State: AOAM531b6Mnsntsq5RqT1n8VFx3BApiSkXxznssnP5Jk/AEYlV6wXman Brcck/LNC23XtHYJ7WK6ozSoOchR7JdunedWif+B6a7fqsGoTzeiIvN8xLA7z5itlz2JQarG1tg LBrFVcUtdNbE0QNMQEakfaS6+ X-Received: by 2002:adf:c3c7:: with SMTP id d7mr17007236wrg.51.1593445797535; Mon, 29 Jun 2020 08:49:57 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwJCjSJAwuxpGqjFO8XbcXjPLwM+eslVQB6/Vp1ldtVTIGaS9N1k5u+Hb4WCmy87/sBSh2Vvg== X-Received: by 2002:adf:c3c7:: with SMTP id d7mr17007220wrg.51.1593445797298; Mon, 29 Jun 2020 08:49:57 -0700 (PDT) Received: from redhat.com (bzq-79-182-31-92.red.bezeqint.net. [79.182.31.92]) by smtp.gmail.com with ESMTPSA id s10sm222118wme.31.2020.06.29.08.49.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jun 2020 08:49:56 -0700 (PDT) Date: Mon, 29 Jun 2020 11:49:53 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, rob.miller@broadcom.com, lingshan.zhu@intel.com, eperezma@redhat.com, lulu@redhat.com, shahafs@mellanox.com, hanand@xilinx.com, mhabets@solarflare.com, gdawar@xilinx.com, saugatm@xilinx.com, vmireyno@marvell.com, zhangweining@ruijie.com.cn, eli@mellanox.com Subject: Re: [PATCH RFC 4/5] vhost-vdpa: support IOTLB batching hints Message-ID: <20200629114607-mutt-send-email-mst@kernel.org> References: <20200618055626.25660-1-jasowang@redhat.com> <20200618055626.25660-5-jasowang@redhat.com> <20200628054940-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 29, 2020 at 05:26:03PM +0800, Jason Wang wrote: > > On 2020/6/28 下午5:58, Michael S. Tsirkin wrote: > > On Thu, Jun 18, 2020 at 01:56:25PM +0800, Jason Wang wrote: > > > This patches extend the vhost IOTLB API to accept batch updating hints > > > form userspace. When userspace wants update the device IOTLB in a > > > batch, it may do: > > > > > > 1) Write vhost_iotlb_msg with VHOST_IOTLB_BATCH_BEGIN flag > > > 2) Perform a batch of IOTLB updating via VHOST_IOTLB_UPDATE/INVALIDATE > > > 3) Write vhost_iotlb_msg with VHOST_IOTLB_BATCH_END flag > > As long as we are extending the interface, > > is there some way we could cut down the number of system calls needed > > here? > > > I'm not sure it's worth to do that since usually we only have less than 10 > regions. Well with a guest iommu I'm guessing it can go up significantly, right? > A possible method is to carry multiple vhost_iotlb_message in one system > call. That's an option. Also, can kernel handle a batch that is too large by applying parts of it iteratively? Or must all changes take place atomically after BATCH_END? If atomically, we might need to limit batch size to make sure kernel can keep a copy in memory. > > > > > > > > Vhost-vdpa may decide to batch the IOMMU/IOTLB updating in step 3 when > > > vDPA device support set_map() ops. This is useful for the vDPA device > > > that want to know all the mappings to tweak their own DMA translation > > > logic. > > > > > > For vDPA device that doesn't require set_map(), no behavior changes. > > > > > > This capability is advertised via VHOST_BACKEND_F_IOTLB_BATCH capability. > > > > > > Signed-off-by: Jason Wang > > > --- > > > drivers/vhost/vdpa.c | 30 +++++++++++++++++++++++------- > > > include/uapi/linux/vhost.h | 2 ++ > > > include/uapi/linux/vhost_types.h | 7 +++++++ > > > 3 files changed, 32 insertions(+), 7 deletions(-) > > > > > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > > > index 453057421f80..8f624bbafee7 100644 > > > --- a/drivers/vhost/vdpa.c > > > +++ b/drivers/vhost/vdpa.c > > > @@ -56,7 +56,9 @@ enum { > > > }; > > > enum { > > > - VHOST_VDPA_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2) > > > + VHOST_VDPA_BACKEND_FEATURES = > > > + (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2) | > > > + (1ULL << VHOST_BACKEND_F_IOTLB_BATCH), > > > }; > > > /* Currently, only network backend w/o multiqueue is supported. */ > > > @@ -77,6 +79,7 @@ struct vhost_vdpa { > > > int virtio_id; > > > int minor; > > > struct eventfd_ctx *config_ctx; > > > + int in_batch; > > > }; > > > static DEFINE_IDA(vhost_vdpa_ida); > > > @@ -125,6 +128,7 @@ static void vhost_vdpa_reset(struct vhost_vdpa *v) > > > const struct vdpa_config_ops *ops = vdpa->config; > > > ops->set_status(vdpa, 0); > > > + v->in_batch = 0; > > > } > > > static long vhost_vdpa_get_device_id(struct vhost_vdpa *v, u8 __user *argp) > > > @@ -540,9 +544,10 @@ static int vhost_vdpa_map(struct vhost_vdpa *v, > > > if (ops->dma_map) > > > r = ops->dma_map(vdpa, iova, size, pa, perm); > > > - else if (ops->set_map) > > > - r = ops->set_map(vdpa, dev->iotlb); > > > - else > > > + else if (ops->set_map) { > > > + if (!v->in_batch) > > > + r = ops->set_map(vdpa, dev->iotlb); > > > + } else > > > r = iommu_map(v->domain, iova, pa, size, > > > perm_to_iommu_flags(perm)); > > > @@ -559,9 +564,10 @@ static void vhost_vdpa_unmap(struct vhost_vdpa *v, u64 iova, u64 size) > > > if (ops->dma_map) > > > ops->dma_unmap(vdpa, iova, size); > > > - else if (ops->set_map) > > > - ops->set_map(vdpa, dev->iotlb); > > > - else > > > + else if (ops->set_map) { > > > + if (!v->in_batch) > > > + ops->set_map(vdpa, dev->iotlb); > > > + } else > > > iommu_unmap(v->domain, iova, size); > > > } > > > @@ -655,6 +661,8 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, > > > struct vhost_iotlb_msg *msg) > > > { > > > struct vhost_vdpa *v = container_of(dev, struct vhost_vdpa, vdev); > > > + struct vdpa_device *vdpa = v->vdpa; > > > + const struct vdpa_config_ops *ops = vdpa->config; > > > int r = 0; > > > r = vhost_dev_check_owner(dev); > > > @@ -668,6 +676,14 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, > > > case VHOST_IOTLB_INVALIDATE: > > > vhost_vdpa_unmap(v, msg->iova, msg->size); > > > break; > > > + case VHOST_IOTLB_BATCH_BEGIN: > > > + v->in_batch = true; > > > + break; > > > + case VHOST_IOTLB_BATCH_END: > > > + if (v->in_batch && ops->set_map) > > > + ops->set_map(vdpa, dev->iotlb); > > > + v->in_batch = false; > > > + break; > > > default: > > > r = -EINVAL; > > > break; > > > diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h > > > index 0c2349612e77..565da96f55d5 100644 > > > --- a/include/uapi/linux/vhost.h > > > +++ b/include/uapi/linux/vhost.h > > > @@ -91,6 +91,8 @@ > > > /* Use message type V2 */ > > > #define VHOST_BACKEND_F_IOTLB_MSG_V2 0x1 > > > +/* IOTLB can accpet batching hints */ > > typo > > > Will fix. > > > > > > > +#define VHOST_BACKEND_F_IOTLB_BATCH 0x2 > > > #define VHOST_SET_BACKEND_FEATURES _IOW(VHOST_VIRTIO, 0x25, __u64) > > > #define VHOST_GET_BACKEND_FEATURES _IOR(VHOST_VIRTIO, 0x26, __u64) > > > diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h > > > index 669457ce5c48..5c12faffdde9 100644 > > > --- a/include/uapi/linux/vhost_types.h > > > +++ b/include/uapi/linux/vhost_types.h > > > @@ -60,6 +60,13 @@ struct vhost_iotlb_msg { > > > #define VHOST_IOTLB_UPDATE 2 > > > #define VHOST_IOTLB_INVALIDATE 3 > > > #define VHOST_IOTLB_ACCESS_FAIL 4 > > > +/* VHOST_IOTLB_BATCH_BEGIN is a hint that userspace will update > > > + * several mappings afterwards. VHOST_IOTLB_BATCH_END is a hint that > > > + * userspace had finished the mapping updating. > > > > Well not just hints - in fact updates do not take place > > until _END. > > > > How about: > > > > /* VHOST_IOTLB_BATCH_BEGIN and VHOST_IOTLB_BATCH_END allow modifying > > * multiple mappings in one go: beginning with > > * VHOST_IOTLB_BATCH_BEGIN, followed by any number of > > VHOST_IOTLB_UPDATE messages, and ending with VHOST_IOTLB_BATCH_END. > > */ > > > That's better. Is there a guarantee that these changes take place atomically? Let's document that. > > > > > > > > When those two flags > > > + * were set, kernel will ignore the rest fileds of the IOTLB message. > > how about: > > > > when one of these two values is used as the message type, the > > rest of the fields in the message are ignored. > > > Yes. > > Will fix. > > Thanks > > > > > > > + */ > > > +#define VHOST_IOTLB_BATCH_BEGIN 5 > > > +#define VHOST_IOTLB_BATCH_END 6 > > > __u8 type; > > > }; > > > -- > > > 2.20.1