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=-6.3 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 4FAA6C47254 for ; Tue, 5 May 2020 09:26:42 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 13327206CC for ; Tue, 5 May 2020 09:26:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="b1BMDI57" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 13327206CC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:54078 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jVtqb-0005yI-92 for qemu-devel@archiver.kernel.org; Tue, 05 May 2020 05:26:41 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47076) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jVtpL-0004r1-TW; Tue, 05 May 2020 05:25:23 -0400 Received: from mail-qv1-xf43.google.com ([2607:f8b0:4864:20::f43]:38259) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jVtpI-0002uY-Qb; Tue, 05 May 2020 05:25:23 -0400 Received: by mail-qv1-xf43.google.com with SMTP id t8so655902qvw.5; Tue, 05 May 2020 02:25:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Yl/pkfWaU0SioytiEHRJk0gXJ0+lNOh2aKwUH484DYo=; b=b1BMDI57Q4dw8epv2P0Z/7f2lxfwEBoIoJppErFyNCZybJcIaxkMq2fN7xDiZLafLV JZ1qm9uQdTasp5UB8fE7gXBKiE11D0GyUtzMamGpA6wVxvb2BrBx5nCnPLQh22T1SOse LJJfH99p42fiMgVbNIKfProVhUgfNo0+dsOv3vfiZt0BXGKGAc2OJgAWgytpKih1Wixh GSgdVMU2XdGMA0Rcjs7XZXwt2LC1GLwXR8nHMrGcbavsEOOtZDeNdg9pF8xRjrBweTmN SRMfChO3vC3TAoB6LrTDpdkxOgBE1VCF/zMyeH8nrtD/GyKfz8TFeCsoo1CoRx3KgROC jGMA== 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; bh=Yl/pkfWaU0SioytiEHRJk0gXJ0+lNOh2aKwUH484DYo=; b=ajW0iDbaILfFgxHQC283RiCCJ6ITc5i6h1EfE53RFz9L4rGC2YNTpZgRwTgNarGMHW Sztw6lRjk+++oNZhpDDizShx9JvlaFIYilG1MnZTxMPxI1/6Q/tL3J4+nNBaqQfxpeVg AAFMwXzQ9pS6D7ispO9ENZLLEMflw1uVtrKdYg0c7PWZUj+wv1EXsV4YvK1scagQ/3BF 8yx5EZAqkiaO8zHPmj8fKsTVze6Pkbtnh3Pdig+AYXWkHaAcgQeihrFXvjwlLvTumR2n QS+c08oRnJmF8ZMT2UWV9dtFYbKrBEe5AB2Mptzj6z7BTSbAdPvKTdWxgeSuemSphvon oIYA== X-Gm-Message-State: AGi0Puab3ElspqcLcDHNdYrIJu0dyz3MvkcC3uxlCXVfBeJe9dhA45a7 5FzuYwdOeD1OC4zP1DTYzlFl/ooywBpS6QtUELU= X-Google-Smtp-Source: APiQypIxgxYizCmd9KRTDhvQomPSPoxWqCZXxG3sgzBh+a1cxAyMW4TsJQLbBev7UB3A59u4n13bPW59ieKjNn0GYCw= X-Received: by 2002:a0c:8262:: with SMTP id h89mr1625074qva.173.1588670719115; Tue, 05 May 2020 02:25:19 -0700 (PDT) MIME-Version: 1.0 References: <20200323084617.1782-1-bbhushan2@marvell.com> <20200323084617.1782-2-bbhushan2@marvell.com> <20200323170835.5021f845@w520.home> <8ec6af3c-6bd7-a3dc-c531-16db6b2089c5@redhat.com> <20200326115318.094ab79a@x1.home> <72e3ea5c-c98c-3e02-26d1-b956ee81e30f@redhat.com> In-Reply-To: <72e3ea5c-c98c-3e02-26d1-b956ee81e30f@redhat.com> From: Bharat Bhushan Date: Tue, 5 May 2020 14:55:06 +0530 Message-ID: Subject: Re: [EXT] Re: [PATCH v9 1/9] hw/vfio/common: Remove error print on mmio region translation by viommu To: Auger Eric Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2607:f8b0:4864:20::f43; envelope-from=bharatb.linux@gmail.com; helo=mail-qv1-xf43.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "yang.zhong@intel.com" , "peter.maydell@linaro.org" , "kevin.tian@intel.com" , "Tomasz Nowicki \[C\]" , "mst@redhat.com" , "drjones@redhat.com" , "peterx@redhat.com" , "qemu-devel@nongnu.org" , Alex Williamson , "qemu-arm@nongnu.org" , "jean-philippe@linaro.org" , Bharat Bhushan , "eric.auger.pro@gmail.com" , "linuc.decode@gmail.com" , David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Eric, On Fri, Apr 24, 2020 at 7:47 PM Auger Eric wrote: > > Hi Bharat, > > On 4/2/20 11:01 AM, Bharat Bhushan wrote: > > Hi Eric/Alex, > > > >> -----Original Message----- > >> From: Alex Williamson > >> Sent: Thursday, March 26, 2020 11:23 PM > >> To: Auger Eric > >> Cc: Bharat Bhushan ; peter.maydell@linaro.org; > >> peterx@redhat.com; eric.auger.pro@gmail.com; kevin.tian@intel.com; > >> mst@redhat.com; Tomasz Nowicki [C] ; > >> drjones@redhat.com; linuc.decode@gmail.com; qemu-devel@nongnu.org; qemu- > >> arm@nongnu.org; bharatb.linux@gmail.com; jean-philippe@linaro.org; > >> yang.zhong@intel.com; David Gibson > >> Subject: [EXT] Re: [PATCH v9 1/9] hw/vfio/common: Remove error print on mmio > >> region translation by viommu > >> > >> External Email > >> > >> ---------------------------------------------------------------------- > >> On Thu, 26 Mar 2020 18:35:48 +0100 > >> Auger Eric wrote: > >> > >>> Hi Alex, > >>> > >>> On 3/24/20 12:08 AM, Alex Williamson wrote: > >>>> [Cc +dwg who originated this warning] > >>>> > >>>> On Mon, 23 Mar 2020 14:16:09 +0530 > >>>> Bharat Bhushan wrote: > >>>> > >>>>> On ARM, the MSI doorbell is translated by the virtual IOMMU. > >>>>> As such address_space_translate() returns the MSI controller MMIO > >>>>> region and we get an "iommu map to non memory area" > >>>>> message. Let's remove this latter. > >>>>> > >>>>> Signed-off-by: Eric Auger > >>>>> Signed-off-by: Bharat Bhushan > >>>>> --- > >>>>> hw/vfio/common.c | 2 -- > >>>>> 1 file changed, 2 deletions(-) > >>>>> > >>>>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c index > >>>>> 5ca11488d6..c586edf47a 100644 > >>>>> --- a/hw/vfio/common.c > >>>>> +++ b/hw/vfio/common.c > >>>>> @@ -426,8 +426,6 @@ static bool vfio_get_vaddr(IOMMUTLBEntry *iotlb, > >> void **vaddr, > >>>>> &xlat, &len, writable, > >>>>> MEMTXATTRS_UNSPECIFIED); > >>>>> if (!memory_region_is_ram(mr)) { > >>>>> - error_report("iommu map to non memory area %"HWADDR_PRIx"", > >>>>> - xlat); > >>>>> return false; > >>>>> } > >>>>> > >>>> > >>>> I'm a bit confused here, I think we need more justification beyond > >>>> "we hit this warning and we don't want to because it's ok in this > >>>> one special case, therefore remove it". I assume the special case > >>>> is that the device MSI address is managed via the SET_IRQS ioctl and > >>>> therefore we won't actually get DMAs to this range. > >>> Yes exactly. The guest creates a mapping between one giova and this > >>> gpa (corresponding to the MSI controller doorbell) because MSIs are > >>> mapped on ARM. But practically the physical device is programmed with > >>> an host chosen iova that maps onto the physical MSI controller's > >>> doorbell. so the device never performs DMA accesses to this range. > >>> > >>> But I imagine the case that > >>>> was in mind when adding this warning was general peer-to-peer > >>>> between and assigned and emulated device. > >>> yes makes sense. > >>> > >>> Maybe there's an argument to be made > >>>> that such a p2p mapping might also be used in a non-vIOMMU case. We > >>>> skip creating those mappings and drivers continue to work, maybe > >>>> because nobody attempts to do p2p DMA with the types of devices we > >>>> emulate, maybe because p2p DMA is not absolutely reliable on bare > >>>> metal and drivers test it before using it. > >>> MSI doorbells are mapped using the IOMMU_MMIO flag (dma-iommu.c > >>> iommu_dma_get_msi_page). > >>> One idea could be to pass that flag through the IOMMU Notifier > >>> mechanism into the iotlb->perm. Eventually when we get this in > >>> vfio_get_vaddr() we would not print the warning. Could that make sense? > >> > >> Yeah, if we can identify a valid case that doesn't need a warning, that's fine by me. > >> Thanks, > > > > Let me know if I understood the proposal correctly: > > > > virtio-iommu driver in guest will make map (VIRTIO_IOMMU_T_MAP) with VIRTIO_IOMMU_MAP_F_MMIO flag for MSI mapping. > > In qemu, virtio-iommu device will set a new defined flag (say IOMMU_MMIO) in iotlb->perm in memory_region_notify_iommu(). vfio_get_vaddr() will check same flag and will not print the warning.> > > Is above correct? > Yes that's what I had in mind. In that case virtio-iommu driver in guest should not make map (VIRTIO_IOMMU_T_MAP) call as it known nothing to be mapped. Stay Safe Thanks -Bharat > > Thanks > > Eric > > > > Thanks > > -Bharat > > > >> > >> Alex > > > > >