From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 2C131A04DC for ; Fri, 16 Oct 2020 09:10:56 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id A27441EAB6; Fri, 16 Oct 2020 09:10:54 +0200 (CEST) Received: from mail-pl1-f195.google.com (mail-pl1-f195.google.com [209.85.214.195]) by dpdk.org (Postfix) with ESMTP id D60E41D72A; Fri, 16 Oct 2020 09:10:50 +0200 (CEST) Received: by mail-pl1-f195.google.com with SMTP id o9so762794plx.10; Fri, 16 Oct 2020 00:10:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=zaYyL+9Cd0Fa0Cb6zuIHvbhiNSJ672+bFT0pyl0iefc=; b=Tk0J4ZEyI9SH5HL0VxE1gOF4cINjXHZGfCx1hylRK+7dfG7V8uo+IP3QPQIgK44lOV TJFvHM95wetOnBTivnVeHxRc8IgG8wB3TfboJGmo3VRMW03Dp1ZXJsh7k0CyBKJLiYcf WHyEAgnYUoedy3Is38z02IopVRpE6lLHSgRCG2SmO/YBEQ1ib9z+dYhOlXAQji3uLdpx lqHHQHyzd6fT3sOigQCPMk48wdTkIIkj/60P/TpjCHGAcOQa/2jXbnweoAWYmUs2gDgl YbYUaKGHCSNowmVUwYz36etDBMhAkz1SvKiukhTvfYLY93CG5XNIjrCxJOZA8PxjauSJ TNfA== 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:in-reply-to:user-agent; bh=zaYyL+9Cd0Fa0Cb6zuIHvbhiNSJ672+bFT0pyl0iefc=; b=pRapqwcxiZyXQQSbgYr5HuW61HvXHsgTeqHDCaqG9g83ijCn7L2DvF1Kti0ZvhjOAh s6K00Yb1GaFW8qerANOZawwIHouvrsbAUOPjFc70+ZtChB41vpeZnYVrRCBAlRvj1MgP YF2dbNCBy0Q0r+1sxtYkhcF8cr46puqx4QN9DkPZmXSHBbGbbAdm1hljOTSOFJCr/e7O fotLhnU9Vq8u4y/ScJqnA1BZpCoo1OJJRrg0moUm5BpYKiHBDipZYZRdrsNttDSMYjDt InDU8RfqG3GsQx5lFe1/ompJQLKKmAoKeZu6j4/HimhbkUs+p36QNbx82aih5Ew7XMYW MIJw== X-Gm-Message-State: AOAM533MUKQNyd4ec2aFbmkNJZUTTSDs8eoTLXPLZjUBuT82rJ0s+B1N NCwXNQEXI4nFEPpp9o3KtY8= X-Google-Smtp-Source: ABdhPJwcg0eYtSj/n0668uz5kjfxAMov8IEAt/BSnemtqK0g5NT64DlpIjo32hDhdYkBdA5fbzhlaw== X-Received: by 2002:a17:90a:9ab:: with SMTP id 40mr2550370pjo.26.1602832248822; Fri, 16 Oct 2020 00:10:48 -0700 (PDT) Received: from gmail.com ([1.6.215.26]) by smtp.gmail.com with ESMTPSA id w16sm1615203pfn.148.2020.10.16.00.10.46 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 16 Oct 2020 00:10:48 -0700 (PDT) Date: Fri, 16 Oct 2020 12:40:40 +0530 From: Nithin Dabilpuram To: "Burakov, Anatoly" Cc: Jerin Jacob , dev@dpdk.org, stable@dpdk.org Message-ID: <20201016071015.GA22749@gmail.com> References: <20201012081106.10610-1-ndabilpuram@marvell.com> <20201012081106.10610-3-ndabilpuram@marvell.com> <05afb7f5-96bf-dffd-15dd-2024586f7290@intel.com> <20201015060914.GA32207@outlook.office365.com> <66b61bda-03a8-d4c4-af9f-0f90a6ef956d@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <66b61bda-03a8-d4c4-af9f-0f90a6ef956d@intel.com> User-Agent: Mutt/1.12.2 (34cd43c) (2019-09-21) Subject: Re: [dpdk-stable] [dpdk-dev] [EXT] Re: [PATCH 2/2] vfio: fix partial DMA unmapping for VFIO type1 X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: stable-bounces@dpdk.org Sender: "stable" On Thu, Oct 15, 2020 at 04:10:31PM +0100, Burakov, Anatoly wrote: > On 15-Oct-20 12:57 PM, Nithin Dabilpuram wrote: > > On Thu, Oct 15, 2020 at 3:31 PM Burakov, Anatoly > > wrote: > > > > > > On 15-Oct-20 7:09 AM, Nithin Dabilpuram wrote: > > > > On Wed, Oct 14, 2020 at 04:07:10PM +0100, Burakov, Anatoly wrote: > > > > > External Email > > > > > > > > > > ---------------------------------------------------------------------- > > > > > On 12-Oct-20 9:11 AM, Nithin Dabilpuram wrote: > > > > > > Partial unmapping is not supported for VFIO IOMMU type1 > > > > > > by kernel. Though kernel gives return as zero, the unmapped size > > > > > > returned will not be same as expected. So check for > > > > > > returned unmap size and return error. > > > > > > > > > > > > For case of DMA map/unmap triggered by heap allocations, > > > > > > maintain granularity of memseg page size so that heap > > > > > > expansion and contraction does not have this issue. > > > > > > > > > > This is quite unfortunate, because there was a different bug that had to do > > > > > with kernel having a very limited number of mappings available [1], as a > > > > > result of which the page concatenation code was added. > > > > > > > > > > It should therefore be documented that the dma_entry_limit parameter should > > > > > be adjusted should the user run out of the DMA entries. > > > > > > > > > > [1] https://urldefense.proofpoint.com/v2/url?u=https-3A__lore.kernel.org_lkml_155414977872.12780.13728555131525362206.stgit-40gimli.home_T_&d=DwICaQ&c=nKjWec2b6R0mOyPaz7xtfQ&r=FZ_tPCbgFOh18zwRPO9H0yDx8VW38vuapifdDfc8SFQ&m=3GMg-634_cdUCY4WpQPwjzZ_S4ckuMHOnt2FxyyjXMk&s=TJLzppkaDS95VGyRHX2hzflQfb9XLK0OiOszSXoeXKk&e= > > > > > > > > > > > > > > > RTE_LOG(ERR, EAL, " cannot clear DMA remapping, error %i (%s)\n", > > > > > > errno, strerror(errno)); > > > > > > return -1; > > > > > > + } else if (dma_unmap.size != len) { > > > > > > + RTE_LOG(ERR, EAL, " unexpected size %"PRIu64" of DMA " > > > > > > + "remapping cleared instead of %"PRIu64"\n", > > > > > > + (uint64_t)dma_unmap.size, len); > > > > > > + rte_errno = EIO; > > > > > > + return -1; > > > > > > } > > > > > > } > > > > > > @@ -1853,6 +1869,12 @@ container_dma_unmap(struct vfio_config *vfio_cfg, uint64_t vaddr, uint64_t iova, > > > > > > /* we're partially unmapping a previously mapped region, so we > > > > > > * need to split entry into two. > > > > > > */ > > > > > > + if (!vfio_cfg->vfio_iommu_type->partial_unmap) { > > > > > > + RTE_LOG(DEBUG, EAL, "DMA partial unmap unsupported\n"); > > > > > > + rte_errno = ENOTSUP; > > > > > > + ret = -1; > > > > > > + goto out; > > > > > > + } > > > > > > > > > > How would we ever arrive here if we never do more than 1 page worth of > > > > > memory anyway? I don't think this is needed. > > > > > > > > container_dma_unmap() is called by user via rte_vfio_container_dma_unmap() > > > > and when he maps we don't split it as we don't about his memory. > > > > So if he maps multiple pages and tries to unmap partially, then we should fail. > > > > > > Should we map it in page granularity then, instead of adding this > > > discrepancy between EAL and user mapping? I.e. instead of adding a > > > workaround, how about we just do the same thing for user mem mappings? > > > > > In heap mapping's we map and unmap it at huge page granularity as we will always > > maintain that. > > > > But here I think we don't know if user's allocation is huge page or > > collection of system > > pages. Only thing we can do here is map it at system page granularity which > > could waste entries if he say really is working with hugepages. Isn't ? > > > > Yeah we do. The API mandates the pages granularity, and it will check > against page size and number of IOVA entries, so yes, we do enforce the fact > that the IOVA addresses supplied by the user have to be page addresses. If I see rte_vfio_container_dma_map(), there is no mention of Huge page size user is providing or we computing. He can call rte_vfio_container_dma_map() with 1GB huge page or 4K system page. Am I missing something ? > > -- > Thanks, > Anatoly