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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 9D2D5C11D24 for ; Fri, 21 Feb 2020 03:42:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 702B4208C4 for ; Fri, 21 Feb 2020 03:42:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NnDOGv1L" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729721AbgBUDmR (ORCPT ); Thu, 20 Feb 2020 22:42:17 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:42246 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729630AbgBUDmQ (ORCPT ); Thu, 20 Feb 2020 22:42:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582256535; 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=a9R0CosE6GfsLGrjcvEZLtqtG2P/xZ2EzhZiapF0r40=; b=NnDOGv1LEM4FSXHrp/MzpuMq3pUC8D84cHeMdWO46mFJkCqDGrCNF8P8shSREeXtwyiE3U M7IcB3WKR8RQzLb0C4tLi9CFKjBR6d/6EgMGEnQWgTx6C4luKpsrSLB5e8KgNp+07iRTCJ 05F8WRFTXlLJBQF1uKJ8bhKRlLj8Tjo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-87-StAG8-9rMQ-MWoQGwwCsyQ-1; Thu, 20 Feb 2020 22:42:11 -0500 X-MC-Unique: StAG8-9rMQ-MWoQGwwCsyQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6E8ECDBA3; Fri, 21 Feb 2020 03:42:08 +0000 (UTC) Received: from [10.72.13.208] (ovpn-13-208.pek2.redhat.com [10.72.13.208]) by smtp.corp.redhat.com (Postfix) with ESMTP id 71D391001281; Fri, 21 Feb 2020 03:41:59 +0000 (UTC) Subject: Re: [PATCH 2/2] virtio: let virtio use DMA API when guest RAM is protected To: David Gibson , Christoph Hellwig Cc: Halil Pasic , "Michael S. Tsirkin" , Marek Szyprowski , Robin Murphy , linux-s390@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Christian Borntraeger , Janosch Frank , Viktor Mihajlovski , Cornelia Huck , Ram Pai , Thiago Jung Bauermann , "Lendacky, Thomas" , Michael Mueller References: <20200220160606.53156-1-pasic@linux.ibm.com> <20200220160606.53156-3-pasic@linux.ibm.com> <20200220161309.GB12709@lst.de> <20200221025915.GB2298@umbus.fritz.box> From: Jason Wang Message-ID: <8194d502-07d8-b798-a2b5-606a8c05b895@redhat.com> Date: Fri, 21 Feb 2020 11:41:57 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20200221025915.GB2298@umbus.fritz.box> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/2/21 =E4=B8=8A=E5=8D=8810:59, David Gibson wrote: > On Thu, Feb 20, 2020 at 05:13:09PM +0100, Christoph Hellwig wrote: >> On Thu, Feb 20, 2020 at 05:06:06PM +0100, Halil Pasic wrote: >>> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_rin= g.c >>> index 867c7ebd3f10..fafc8f924955 100644 >>> --- a/drivers/virtio/virtio_ring.c >>> +++ b/drivers/virtio/virtio_ring.c >>> @@ -243,6 +243,9 @@ static bool vring_use_dma_api(struct virtio_devic= e *vdev) >>> if (!virtio_has_iommu_quirk(vdev)) >>> return true; >>> =20 >>> + if (force_dma_unencrypted(&vdev->dev)) >>> + return true; >> Hell no. This is a detail of the platform DMA direct implementation. >> Drivers have no business looking at this flag, and virtio finally need= s >> to be fixed to use the DMA API properly for everything but legacy devi= ces. > So, this patch definitely isn't right as it stands, but I'm struggling > to understand what it is you're saying is the right way. > > By "legacy devices" I assume you mean pre-virtio-1.0 devices, that > lack the F_VERSION_1 feature flag. Is that right? Because I don't > see how being a legacy device or not relates to use of the DMA API. > > I *think* what you are suggesting here is that virtio devices that > have !F_IOMMU_PLATFORM should have their dma_ops set up so that the > DMA API treats IOVA=3D=3DPA, which will satisfy what the device expects= . Can this work for swiotlb? Thanks > Then the virtio driver can use the DMA API the same way for both > F_IOMMU_PLATFORM and !F_IOMMU_PLATFORM devices. > > But if that works for !F_IOMMU_PLATFORM_DEVICES+F_VERSION_1 devices, > then AFAICT it will work equally well for legacy devices. > > Using the DMA API for *everything* in virtio, legacy or not, seems > like a reasonable approach to me. But, AFAICT, that does require the > DMA layer to have some kind of explicit call to turn on this > behaviour, which the virtio driver would call during initializsation. > I don't think we can do it 100% within the DMA layer, because only the > driver can reasonably know when a device has this weird non-standard > DMA behaviour. > 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=-5.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 3EF26C11D24 for ; Fri, 21 Feb 2020 03:42:23 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 F3A4B208C4 for ; 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bh=a9R0CosE6GfsLGrjcvEZLtqtG2P/xZ2EzhZiapF0r40=; b=NnDOGv1LEM4FSXHrp/MzpuMq3pUC8D84cHeMdWO46mFJkCqDGrCNF8P8shSREeXtwyiE3U M7IcB3WKR8RQzLb0C4tLi9CFKjBR6d/6EgMGEnQWgTx6C4luKpsrSLB5e8KgNp+07iRTCJ 05F8WRFTXlLJBQF1uKJ8bhKRlLj8Tjo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-87-StAG8-9rMQ-MWoQGwwCsyQ-1; Thu, 20 Feb 2020 22:42:11 -0500 X-MC-Unique: StAG8-9rMQ-MWoQGwwCsyQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6E8ECDBA3; Fri, 21 Feb 2020 03:42:08 +0000 (UTC) Received: from [10.72.13.208] (ovpn-13-208.pek2.redhat.com [10.72.13.208]) by smtp.corp.redhat.com (Postfix) with ESMTP id 71D391001281; Fri, 21 Feb 2020 03:41:59 +0000 (UTC) Subject: Re: [PATCH 2/2] virtio: let virtio use DMA API when guest RAM is protected To: David Gibson , Christoph Hellwig References: <20200220160606.53156-1-pasic@linux.ibm.com> <20200220160606.53156-3-pasic@linux.ibm.com> <20200220161309.GB12709@lst.de> <20200221025915.GB2298@umbus.fritz.box> From: Jason Wang Message-ID: <8194d502-07d8-b798-a2b5-606a8c05b895@redhat.com> Date: Fri, 21 Feb 2020 11:41:57 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20200221025915.GB2298@umbus.fritz.box> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Cc: linux-s390@vger.kernel.org, Janosch Frank , "Michael S. Tsirkin" , Cornelia Huck , Ram Pai , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Halil Pasic , Christian Borntraeger , iommu@lists.linux-foundation.org, Michael Mueller , "Lendacky, Thomas" , Viktor Mihajlovski , Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Ck9uIDIwMjAvMi8yMSDkuIrljYgxMDo1OSwgRGF2aWQgR2lic29uIHdyb3RlOgo+IE9uIFRodSwg RmViIDIwLCAyMDIwIGF0IDA1OjEzOjA5UE0gKzAxMDAsIENocmlzdG9waCBIZWxsd2lnIHdyb3Rl Ogo+PiBPbiBUaHUsIEZlYiAyMCwgMjAyMCBhdCAwNTowNjowNlBNICswMTAwLCBIYWxpbCBQYXNp YyB3cm90ZToKPj4+IGRpZmYgLS1naXQgYS9kcml2ZXJzL3ZpcnRpby92aXJ0aW9fcmluZy5jIGIv ZHJpdmVycy92aXJ0aW8vdmlydGlvX3JpbmcuYwo+Pj4gaW5kZXggODY3YzdlYmQzZjEwLi5mYWZj OGY5MjQ5NTUgMTAwNjQ0Cj4+PiAtLS0gYS9kcml2ZXJzL3ZpcnRpby92aXJ0aW9fcmluZy5jCj4+ PiArKysgYi9kcml2ZXJzL3ZpcnRpby92aXJ0aW9fcmluZy5jCj4+PiBAQCAtMjQzLDYgKzI0Myw5 IEBAIHN0YXRpYyBib29sIHZyaW5nX3VzZV9kbWFfYXBpKHN0cnVjdCB2aXJ0aW9fZGV2aWNlICp2 ZGV2KQo+Pj4gICAJaWYgKCF2aXJ0aW9faGFzX2lvbW11X3F1aXJrKHZkZXYpKQo+Pj4gICAJCXJl dHVybiB0cnVlOwo+Pj4gICAKPj4+ICsJaWYgKGZvcmNlX2RtYV91bmVuY3J5cHRlZCgmdmRldi0+ ZGV2KSkKPj4+ICsJCXJldHVybiB0cnVlOwo+PiBIZWxsIG5vLiAgVGhpcyBpcyBhIGRldGFpbCBv ZiB0aGUgcGxhdGZvcm0gRE1BIGRpcmVjdCBpbXBsZW1lbnRhdGlvbi4KPj4gRHJpdmVycyBoYXZl IG5vIGJ1c2luZXNzIGxvb2tpbmcgYXQgdGhpcyBmbGFnLCBhbmQgdmlydGlvIGZpbmFsbHkgbmVl ZHMKPj4gdG8gYmUgZml4ZWQgdG8gdXNlIHRoZSBETUEgQVBJIHByb3Blcmx5IGZvciBldmVyeXRo aW5nIGJ1dCBsZWdhY3kgZGV2aWNlcy4KPiBTbywgdGhpcyBwYXRjaCBkZWZpbml0ZWx5IGlzbid0 IHJpZ2h0IGFzIGl0IHN0YW5kcywgYnV0IEknbSBzdHJ1Z2dsaW5nCj4gdG8gdW5kZXJzdGFuZCB3 aGF0IGl0IGlzIHlvdSdyZSBzYXlpbmcgaXMgdGhlIHJpZ2h0IHdheS4KPgo+IEJ5ICJsZWdhY3kg ZGV2aWNlcyIgSSBhc3N1bWUgeW91IG1lYW4gcHJlLXZpcnRpby0xLjAgZGV2aWNlcywgdGhhdAo+ IGxhY2sgdGhlIEZfVkVSU0lPTl8xIGZlYXR1cmUgZmxhZy4gIElzIHRoYXQgcmlnaHQ/ICBCZWNh dXNlIEkgZG9uJ3QKPiBzZWUgaG93IGJlaW5nIGEgbGVnYWN5IGRldmljZSBvciBub3QgcmVsYXRl cyB0byB1c2Ugb2YgdGhlIERNQSBBUEkuCj4KPiBJICp0aGluayogd2hhdCB5b3UgYXJlIHN1Z2dl c3RpbmcgaGVyZSBpcyB0aGF0IHZpcnRpbyBkZXZpY2VzIHRoYXQKPiBoYXZlICFGX0lPTU1VX1BM QVRGT1JNIHNob3VsZCBoYXZlIHRoZWlyIGRtYV9vcHMgc2V0IHVwIHNvIHRoYXQgdGhlCj4gRE1B IEFQSSB0cmVhdHMgSU9WQT09UEEsIHdoaWNoIHdpbGwgc2F0aXNmeSB3aGF0IHRoZSBkZXZpY2Ug ZXhwZWN0cy4KCgpDYW4gdGhpcyB3b3JrIGZvciBzd2lvdGxiPwoKVGhhbmtzCgoKPiBUaGVuIHRo ZSB2aXJ0aW8gZHJpdmVyIGNhbiB1c2UgdGhlIERNQSBBUEkgdGhlIHNhbWUgd2F5IGZvciBib3Ro Cj4gRl9JT01NVV9QTEFURk9STSBhbmQgIUZfSU9NTVVfUExBVEZPUk0gZGV2aWNlcy4KPgo+IEJ1 dCBpZiB0aGF0IHdvcmtzIGZvciAhRl9JT01NVV9QTEFURk9STV9ERVZJQ0VTK0ZfVkVSU0lPTl8x IGRldmljZXMsCj4gdGhlbiBBRkFJQ1QgaXQgd2lsbCB3b3JrIGVxdWFsbHkgd2VsbCBmb3IgbGVn YWN5IGRldmljZXMuCj4KPiBVc2luZyB0aGUgRE1BIEFQSSBmb3IgKmV2ZXJ5dGhpbmcqIGluIHZp cnRpbywgbGVnYWN5IG9yIG5vdCwgc2VlbXMKPiBsaWtlIGEgcmVhc29uYWJsZSBhcHByb2FjaCB0 byBtZS4gIEJ1dCwgQUZBSUNULCB0aGF0IGRvZXMgcmVxdWlyZSB0aGUKPiBETUEgbGF5ZXIgdG8g aGF2ZSBzb21lIGtpbmQgb2YgZXhwbGljaXQgY2FsbCB0byB0dXJuIG9uIHRoaXMKPiBiZWhhdmlv dXIsIHdoaWNoIHRoZSB2aXJ0aW8gZHJpdmVyIHdvdWxkIGNhbGwgZHVyaW5nIGluaXRpYWxpenNh dGlvbi4KPiBJIGRvbid0IHRoaW5rIHdlIGNhbiBkbyBpdCAxMDAlIHdpdGhpbiB0aGUgRE1BIGxh eWVyLCBiZWNhdXNlIG9ubHkgdGhlCj4gZHJpdmVyIGNhbiByZWFzb25hYmx5IGtub3cgd2hlbiBh IGRldmljZSBoYXMgdGhpcyB3ZWlyZCBub24tc3RhbmRhcmQKPiBETUEgYmVoYXZpb3VyLgo+Cgpf X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwppb21tdSBtYWls aW5nIGxpc3QKaW9tbXVAbGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6Ly9saXN0cy5s aW51eGZvdW5kYXRpb24ub3JnL21haWxtYW4vbGlzdGluZm8vaW9tbXU=