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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 1C460C43142 for ; Fri, 3 Aug 2018 02:42:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C3A3A21724 for ; Fri, 3 Aug 2018 02:41:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C3A3A21724 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727127AbeHCEf7 (ORCPT ); Fri, 3 Aug 2018 00:35:59 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:54310 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726190AbeHCEf7 (ORCPT ); Fri, 3 Aug 2018 00:35:59 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A3E8D8185342; Fri, 3 Aug 2018 02:41:55 +0000 (UTC) Received: from [10.72.12.51] (ovpn-12-51.pek2.redhat.com [10.72.12.51]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A0A602166BA2; Fri, 3 Aug 2018 02:41:44 +0000 (UTC) Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices To: "Michael S. Tsirkin" , Anshuman Khandual Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, aik@ozlabs.ru, robh@kernel.org, joe@perches.com, elfring@users.sourceforge.net, david@gibson.dropbear.id.au, benh@kernel.crashing.org, mpe@ellerman.id.au, hch@infradead.org, linuxram@us.ibm.com, haren@linux.vnet.ibm.com, paulus@samba.org, srikar@linux.vnet.ibm.com References: <20180720035941.6844-1-khandual@linux.vnet.ibm.com> <20180802235332-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: Date: Fri, 3 Aug 2018 10:41:41 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180802235332-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Fri, 03 Aug 2018 02:41:55 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Fri, 03 Aug 2018 02:41:55 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'jasowang@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018年08月03日 04:55, Michael S. Tsirkin wrote: > On Fri, Jul 20, 2018 at 09:29:37AM +0530, Anshuman Khandual wrote: >> This patch series is the follow up on the discussions we had before about >> the RFC titled [RFC,V2] virtio: Add platform specific DMA API translation >> for virito devices (https://patchwork.kernel.org/patch/10417371/). There >> were suggestions about doing away with two different paths of transactions >> with the host/QEMU, first being the direct GPA and the other being the DMA >> API based translations. >> >> First patch attempts to create a direct GPA mapping based DMA operations >> structure called 'virtio_direct_dma_ops' with exact same implementation >> of the direct GPA path which virtio core currently has but just wrapped in >> a DMA API format. Virtio core must use 'virtio_direct_dma_ops' instead of >> the arch default in absence of VIRTIO_F_IOMMU_PLATFORM flag to preserve the >> existing semantics. The second patch does exactly that inside the function >> virtio_finalize_features(). The third patch removes the default direct GPA >> path from virtio core forcing it to use DMA API callbacks for all devices. >> Now with that change, every device must have a DMA operations structure >> associated with it. The fourth patch adds an additional hook which gives >> the platform an opportunity to do yet another override if required. This >> platform hook can be used on POWER Ultravisor based protected guests to >> load up SWIOTLB DMA callbacks to do the required (as discussed previously >> in the above mentioned thread how host is allowed to access only parts of >> the guest GPA range) bounce buffering into the shared memory for all I/O >> scatter gather buffers to be consumed on the host side. >> >> Please go through these patches and review whether this approach broadly >> makes sense. I will appreciate suggestions, inputs, comments regarding >> the patches or the approach in general. Thank you. > Jason did some work on profiling this. Unfortunately he reports > about 4% extra overhead from this switch on x86 with no vIOMMU. The test is rather simple, just run pktgen (pktgen_sample01_simple.sh) in guest and measure PPS on tap on host. Thanks > > I expect he's writing up the data in more detail, but > just wanted to let you know this would be one more > thing to debug before we can just switch to DMA APIs. > > >> Anshuman Khandual (4): >> virtio: Define virtio_direct_dma_ops structure >> virtio: Override device's DMA OPS with virtio_direct_dma_ops selectively >> virtio: Force virtio core to use DMA API callbacks for all virtio devices >> virtio: Add platform specific DMA API translation for virito devices >> >> arch/powerpc/include/asm/dma-mapping.h | 6 +++ >> arch/powerpc/platforms/pseries/iommu.c | 6 +++ >> drivers/virtio/virtio.c | 72 ++++++++++++++++++++++++++++++++++ >> drivers/virtio/virtio_pci_common.h | 3 ++ >> drivers/virtio/virtio_ring.c | 65 +----------------------------- >> 5 files changed, 89 insertions(+), 63 deletions(-) >> >> -- >> 2.9.3 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices Date: Fri, 3 Aug 2018 10:41:41 +0800 Message-ID: References: <20180720035941.6844-1-khandual@linux.vnet.ibm.com> <20180802235332-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <20180802235332-mutt-send-email-mst@kernel.org> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: "Michael S. Tsirkin" , Anshuman Khandual Cc: robh@kernel.org, srikar@linux.vnet.ibm.com, benh@kernel.crashing.org, linuxram@us.ibm.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, hch@infradead.org, paulus@samba.org, mpe@ellerman.id.au, joe@perches.com, linuxppc-dev@lists.ozlabs.org, elfring@users.sourceforge.net, haren@linux.vnet.ibm.com, david@gibson.dropbear.id.au List-Id: virtualization@lists.linuxfoundation.org CgpPbiAyMDE45bm0MDjmnIgwM+aXpSAwNDo1NSwgTWljaGFlbCBTLiBUc2lya2luIHdyb3RlOgo+ IE9uIEZyaSwgSnVsIDIwLCAyMDE4IGF0IDA5OjI5OjM3QU0gKzA1MzAsIEFuc2h1bWFuIEtoYW5k dWFsIHdyb3RlOgo+PiBUaGlzIHBhdGNoIHNlcmllcyBpcyB0aGUgZm9sbG93IHVwIG9uIHRoZSBk aXNjdXNzaW9ucyB3ZSBoYWQgYmVmb3JlIGFib3V0Cj4+IHRoZSBSRkMgdGl0bGVkIFtSRkMsVjJd IHZpcnRpbzogQWRkIHBsYXRmb3JtIHNwZWNpZmljIERNQSBBUEkgdHJhbnNsYXRpb24KPj4gZm9y IHZpcml0byBkZXZpY2VzIChodHRwczovL3BhdGNod29yay5rZXJuZWwub3JnL3BhdGNoLzEwNDE3 MzcxLykuIFRoZXJlCj4+IHdlcmUgc3VnZ2VzdGlvbnMgYWJvdXQgZG9pbmcgYXdheSB3aXRoIHR3 byBkaWZmZXJlbnQgcGF0aHMgb2YgdHJhbnNhY3Rpb25zCj4+IHdpdGggdGhlIGhvc3QvUUVNVSwg Zmlyc3QgYmVpbmcgdGhlIGRpcmVjdCBHUEEgYW5kIHRoZSBvdGhlciBiZWluZyB0aGUgRE1BCj4+ IEFQSSBiYXNlZCB0cmFuc2xhdGlvbnMuCj4+Cj4+IEZpcnN0IHBhdGNoIGF0dGVtcHRzIHRvIGNy ZWF0ZSBhIGRpcmVjdCBHUEEgbWFwcGluZyBiYXNlZCBETUEgb3BlcmF0aW9ucwo+PiBzdHJ1Y3R1 cmUgY2FsbGVkICd2aXJ0aW9fZGlyZWN0X2RtYV9vcHMnIHdpdGggZXhhY3Qgc2FtZSBpbXBsZW1l bnRhdGlvbgo+PiBvZiB0aGUgZGlyZWN0IEdQQSBwYXRoIHdoaWNoIHZpcnRpbyBjb3JlIGN1cnJl bnRseSBoYXMgYnV0IGp1c3Qgd3JhcHBlZCBpbgo+PiBhIERNQSBBUEkgZm9ybWF0LiBWaXJ0aW8g Y29yZSBtdXN0IHVzZSAndmlydGlvX2RpcmVjdF9kbWFfb3BzJyBpbnN0ZWFkIG9mCj4+IHRoZSBh cmNoIGRlZmF1bHQgaW4gYWJzZW5jZSBvZiBWSVJUSU9fRl9JT01NVV9QTEFURk9STSBmbGFnIHRv IHByZXNlcnZlIHRoZQo+PiBleGlzdGluZyBzZW1hbnRpY3MuIFRoZSBzZWNvbmQgcGF0Y2ggZG9l cyBleGFjdGx5IHRoYXQgaW5zaWRlIHRoZSBmdW5jdGlvbgo+PiB2aXJ0aW9fZmluYWxpemVfZmVh dHVyZXMoKS4gVGhlIHRoaXJkIHBhdGNoIHJlbW92ZXMgdGhlIGRlZmF1bHQgZGlyZWN0IEdQQQo+ PiBwYXRoIGZyb20gdmlydGlvIGNvcmUgZm9yY2luZyBpdCB0byB1c2UgRE1BIEFQSSBjYWxsYmFj a3MgZm9yIGFsbCBkZXZpY2VzLgo+PiBOb3cgd2l0aCB0aGF0IGNoYW5nZSwgZXZlcnkgZGV2aWNl IG11c3QgaGF2ZSBhIERNQSBvcGVyYXRpb25zIHN0cnVjdHVyZQo+PiBhc3NvY2lhdGVkIHdpdGgg aXQuIFRoZSBmb3VydGggcGF0Y2ggYWRkcyBhbiBhZGRpdGlvbmFsIGhvb2sgd2hpY2ggZ2l2ZXMK Pj4gdGhlIHBsYXRmb3JtIGFuIG9wcG9ydHVuaXR5IHRvIGRvIHlldCBhbm90aGVyIG92ZXJyaWRl IGlmIHJlcXVpcmVkLiBUaGlzCj4+IHBsYXRmb3JtIGhvb2sgY2FuIGJlIHVzZWQgb24gUE9XRVIg VWx0cmF2aXNvciBiYXNlZCBwcm90ZWN0ZWQgZ3Vlc3RzIHRvCj4+IGxvYWQgdXAgU1dJT1RMQiBE TUEgY2FsbGJhY2tzIHRvIGRvIHRoZSByZXF1aXJlZCAoYXMgZGlzY3Vzc2VkIHByZXZpb3VzbHkK Pj4gaW4gdGhlIGFib3ZlIG1lbnRpb25lZCB0aHJlYWQgaG93IGhvc3QgaXMgYWxsb3dlZCB0byBh Y2Nlc3Mgb25seSBwYXJ0cyBvZgo+PiB0aGUgZ3Vlc3QgR1BBIHJhbmdlKSBib3VuY2UgYnVmZmVy aW5nIGludG8gdGhlIHNoYXJlZCBtZW1vcnkgZm9yIGFsbCBJL08KPj4gc2NhdHRlciBnYXRoZXIg YnVmZmVycyB0byBiZSBjb25zdW1lZCBvbiB0aGUgaG9zdCBzaWRlLgo+Pgo+PiBQbGVhc2UgZ28g dGhyb3VnaCB0aGVzZSBwYXRjaGVzIGFuZCByZXZpZXcgd2hldGhlciB0aGlzIGFwcHJvYWNoIGJy b2FkbHkKPj4gbWFrZXMgc2Vuc2UuIEkgd2lsbCBhcHByZWNpYXRlIHN1Z2dlc3Rpb25zLCBpbnB1 dHMsIGNvbW1lbnRzIHJlZ2FyZGluZwo+PiB0aGUgcGF0Y2hlcyBvciB0aGUgYXBwcm9hY2ggaW4g Z2VuZXJhbC4gVGhhbmsgeW91Lgo+IEphc29uIGRpZCBzb21lIHdvcmsgb24gcHJvZmlsaW5nIHRo aXMuIFVuZm9ydHVuYXRlbHkgaGUgcmVwb3J0cwo+IGFib3V0IDQlIGV4dHJhIG92ZXJoZWFkIGZy b20gdGhpcyBzd2l0Y2ggb24geDg2IHdpdGggbm8gdklPTU1VLgoKVGhlIHRlc3QgaXMgcmF0aGVy IHNpbXBsZSwganVzdCBydW4gcGt0Z2VuIChwa3RnZW5fc2FtcGxlMDFfc2ltcGxlLnNoKSAKaW4g Z3Vlc3QgYW5kIG1lYXN1cmUgUFBTIG9uIHRhcCBvbiBob3N0LgoKVGhhbmtzCgo+Cj4gSSBleHBl Y3QgaGUncyB3cml0aW5nIHVwIHRoZSBkYXRhIGluIG1vcmUgZGV0YWlsLCBidXQKPiBqdXN0IHdh bnRlZCB0byBsZXQgeW91IGtub3cgdGhpcyB3b3VsZCBiZSBvbmUgbW9yZQo+IHRoaW5nIHRvIGRl YnVnIGJlZm9yZSB3ZSBjYW4ganVzdCBzd2l0Y2ggdG8gRE1BIEFQSXMuCj4KPgo+PiBBbnNodW1h biBLaGFuZHVhbCAoNCk6Cj4+ICAgIHZpcnRpbzogRGVmaW5lIHZpcnRpb19kaXJlY3RfZG1hX29w cyBzdHJ1Y3R1cmUKPj4gICAgdmlydGlvOiBPdmVycmlkZSBkZXZpY2UncyBETUEgT1BTIHdpdGgg dmlydGlvX2RpcmVjdF9kbWFfb3BzIHNlbGVjdGl2ZWx5Cj4+ICAgIHZpcnRpbzogRm9yY2Ugdmly dGlvIGNvcmUgdG8gdXNlIERNQSBBUEkgY2FsbGJhY2tzIGZvciBhbGwgdmlydGlvIGRldmljZXMK Pj4gICAgdmlydGlvOiBBZGQgcGxhdGZvcm0gc3BlY2lmaWMgRE1BIEFQSSB0cmFuc2xhdGlvbiBm b3IgdmlyaXRvIGRldmljZXMKPj4KPj4gICBhcmNoL3Bvd2VycGMvaW5jbHVkZS9hc20vZG1hLW1h cHBpbmcuaCB8ICA2ICsrKwo+PiAgIGFyY2gvcG93ZXJwYy9wbGF0Zm9ybXMvcHNlcmllcy9pb21t dS5jIHwgIDYgKysrCj4+ICAgZHJpdmVycy92aXJ0aW8vdmlydGlvLmMgICAgICAgICAgICAgICAg fCA3MiArKysrKysrKysrKysrKysrKysrKysrKysrKysrKysrKysrCj4+ICAgZHJpdmVycy92aXJ0 aW8vdmlydGlvX3BjaV9jb21tb24uaCAgICAgfCAgMyArKwo+PiAgIGRyaXZlcnMvdmlydGlvL3Zp cnRpb19yaW5nLmMgICAgICAgICAgIHwgNjUgKy0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0t Cj4+ICAgNSBmaWxlcyBjaGFuZ2VkLCA4OSBpbnNlcnRpb25zKCspLCA2MyBkZWxldGlvbnMoLSkK Pj4KPj4gLS0gCj4+IDIuOS4zCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fXwpWaXJ0dWFsaXphdGlvbiBtYWlsaW5nIGxpc3QKVmlydHVhbGl6YXRpb25AbGlz dHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6Ly9saXN0cy5saW51eGZvdW5kYXRpb24ub3Jn L21haWxtYW4vbGlzdGluZm8vdmlydHVhbGl6YXRpb24=