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=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 31A8CC433ED for ; Thu, 8 Apr 2021 05:27:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DEC8961165 for ; Thu, 8 Apr 2021 05:27:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229718AbhDHF1x (ORCPT ); Thu, 8 Apr 2021 01:27:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46200 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229523AbhDHF1u (ORCPT ); Thu, 8 Apr 2021 01:27:50 -0400 Received: from mail-ed1-x52e.google.com (mail-ed1-x52e.google.com [IPv6:2a00:1450:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4D9E5C061762 for ; Wed, 7 Apr 2021 22:27:39 -0700 (PDT) Received: by mail-ed1-x52e.google.com with SMTP id g17so76722edm.6 for ; Wed, 07 Apr 2021 22:27:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=XBsyg95HvfPCaEnZTpjOKu7MER6UdAU2kaoMscYQi8Y=; b=jYfsBh72CrskhMRxL/8IYLk38hnv+O5xRQIsaEaOfaaGv6MA8Js14HzL5sJZWiXhNL 4vVpaQx4FKRolEe2JaiSI737LSOgjNz70Wvign3n/6dEKYvnmoPeu52M1I5KN3rVRfLG u59LSRgb//zUFWs2xHSFXUj1fBed9EJiD23RGbQPzNO7GCwrI4OzqIv3lwF2Ya3yiC5K 9YkKazmFV9NsHEmi7KI74lApFXX+jGWDjYqn0qG2qumU3w1xUFkkVJ/sFXvkGbZInEuR +dN7BY7FKVBwQWkVQzQwf41tAO9mQAY3/9eMYlEMJTt86hRFkrs3jS+jvTfJ8IeS/IZI j7dw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=XBsyg95HvfPCaEnZTpjOKu7MER6UdAU2kaoMscYQi8Y=; b=Pum1oOqGjzfpMkMMAiKGT8O7DnMSmr24Xr2lC7mGeppocYTIq1ZMzKkeExrNlas4mX p0wPxLnabE4iTG5/j9NYqmTFHnK5Qc05M5EDby604PqZ32F5lfSPWytl4UmjnAfjm2JT XrS1oKEooFQnGPYrxr/WOFiotRqrWPMLw0rQyYCCaLNbB6pcaZpfNWgyHYMD7I3rc6Nx hbUDQ2DEfOXrnNN8tTcrHMP8INCpIC+HSCf/CwN/mjvtjkClsPCOzVwYqDOCT8IyxUp5 4qEvX1gMXoncoxeGF4DwvAV8DNnTFKc6gNv3/l8g0XZEuzU2rsCHeuYEWXUDxNPljRSS tglg== X-Gm-Message-State: AOAM532vE7EQ8g6efv9iEMYa0n/3sCZYxCryCjc5z0Ee6nhNz6R+I2v/ dzDiWYLUyx9F1jYQ+smUG/Fob40t18LItIf10PFm X-Google-Smtp-Source: ABdhPJw3cYEhtTY5BHRxiZkL1RHpeWMZaV4LAjqbpGDcn482YygWtNBA4BmOQyKwYeeY/hJkcq9H4uHf1KkDuCYwyek= X-Received: by 2002:a05:6402:6ca:: with SMTP id n10mr8976690edy.312.1617859657831; Wed, 07 Apr 2021 22:27:37 -0700 (PDT) MIME-Version: 1.0 References: <20210331080519.172-1-xieyongji@bytedance.com> <20210331080519.172-9-xieyongji@bytedance.com> <30862242-293b-f42f-d8ce-2c31a52e3697@redhat.com> In-Reply-To: <30862242-293b-f42f-d8ce-2c31a52e3697@redhat.com> From: Yongji Xie Date: Thu, 8 Apr 2021 13:27:27 +0800 Message-ID: Subject: Re: Re: [PATCH v6 08/10] vduse: Implement an MMU-based IOMMU driver To: Jason Wang Cc: "Michael S. Tsirkin" , Stefan Hajnoczi , Stefano Garzarella , Parav Pandit , Christoph Hellwig , Christian Brauner , Randy Dunlap , Matthew Wilcox , viro@zeniv.linux.org.uk, Jens Axboe , bcrl@kvack.org, Jonathan Corbet , =?UTF-8?Q?Mika_Penttil=C3=A4?= , Dan Carpenter , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Apr 8, 2021 at 11:26 AM Jason Wang wrote: > > > =E5=9C=A8 2021/3/31 =E4=B8=8B=E5=8D=884:05, Xie Yongji =E5=86=99=E9=81=93= : > > This implements an MMU-based IOMMU driver to support mapping > > kernel dma buffer into userspace. The basic idea behind it is > > treating MMU (VA->PA) as IOMMU (IOVA->PA). The driver will set > > up MMU mapping instead of IOMMU mapping for the DMA transfer so > > that the userspace process is able to use its virtual address to > > access the dma buffer in kernel. > > > > And to avoid security issue, a bounce-buffering mechanism is > > introduced to prevent userspace accessing the original buffer > > directly. > > > > Signed-off-by: Xie Yongji > > > Acked-by: Jason Wang > > With some nits: > > > > --- > > drivers/vdpa/vdpa_user/iova_domain.c | 521 ++++++++++++++++++++++++++= +++++++++ > > drivers/vdpa/vdpa_user/iova_domain.h | 70 +++++ > > 2 files changed, 591 insertions(+) > > create mode 100644 drivers/vdpa/vdpa_user/iova_domain.c > > create mode 100644 drivers/vdpa/vdpa_user/iova_domain.h > > > [...] > > > > +static void vduse_domain_bounce(struct vduse_iova_domain *domain, > > + dma_addr_t iova, size_t size, > > + enum dma_data_direction dir) > > +{ > > + struct vduse_bounce_map *map; > > + unsigned int offset; > > + void *addr; > > + size_t sz; > > + > > + while (size) { > > + map =3D &domain->bounce_maps[iova >> PAGE_SHIFT]; > > + offset =3D offset_in_page(iova); > > + sz =3D min_t(size_t, PAGE_SIZE - offset, size); > > + > > + if (WARN_ON(!map->bounce_page || > > + map->orig_phys =3D=3D INVALID_PHYS_ADDR)) > > + return; > > + > > + addr =3D page_address(map->bounce_page) + offset; > > + do_bounce(map->orig_phys + offset, addr, sz, dir); > > + size -=3D sz; > > + iova +=3D sz; > > + } > > +} > > + > > +static struct page * > > +vduse_domain_get_mapping_page(struct vduse_iova_domain *domain, u64 io= va) > > > It's better to rename this as "vduse_domain_get_coherent_page?". > OK. > > > +{ > > + u64 start =3D iova & PAGE_MASK; > > + u64 last =3D start + PAGE_SIZE - 1; > > + struct vhost_iotlb_map *map; > > + struct page *page =3D NULL; > > + > > + spin_lock(&domain->iotlb_lock); > > + map =3D vhost_iotlb_itree_first(domain->iotlb, start, last); > > + if (!map) > > + goto out; > > + > > + page =3D pfn_to_page((map->addr + iova - map->start) >> PAGE_SHIF= T); > > + get_page(page); > > +out: > > + spin_unlock(&domain->iotlb_lock); > > + > > + return page; > > +} > > + > > > [...] > > > > + > > +static dma_addr_t > > +vduse_domain_alloc_iova(struct iova_domain *iovad, > > + unsigned long size, unsigned long limit) > > +{ > > + unsigned long shift =3D iova_shift(iovad); > > + unsigned long iova_len =3D iova_align(iovad, size) >> shift; > > + unsigned long iova_pfn; > > + > > + if (iova_len < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1))) > > + iova_len =3D roundup_pow_of_two(iova_len); > > > Let's add a comment as what has been done in dma-iommu.c? > Fine. > (In the future, it looks to me it's better to move them to > alloc_iova_fast()). > Agree. Thanks, Yongji