From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH 3/5] vDPA: introduce vDPA bus Date: Tue, 21 Jan 2020 11:32:43 +0800 Message-ID: References: <20200116124231.20253-1-jasowang@redhat.com> <20200116124231.20253-4-jasowang@redhat.com> <20200117070324-mutt-send-email-mst@kernel.org> <239b042c-2d9e-0eec-a1ef-b03b7e2c5419@redhat.com> <20200119045849-mutt-send-email-mst@kernel.org> <20200120070710-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20200120070710-mutt-send-email-mst@kernel.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: "Michael S. Tsirkin" Cc: Shahaf Shuler , Rob Miller , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "virtualization@lists.linux-foundation.org" , Netdev , "Bie, Tiwei" , Jason Gunthorpe , "maxime.coquelin@redhat.com" , "Liang, Cunming" , "Wang, Zhihong" , "Wang, Xiao W" , "haotian.wang@sifive.com" , "Zhu, Lingshan" , "eperezma@redhat.com" , "lulu@redhat.com" , Parav Pandit List-Id: virtualization@lists.linuxfoundation.org On 2020/1/20 =E4=B8=8B=E5=8D=888:09, Michael S. Tsirkin wrote: > On Mon, Jan 20, 2020 at 04:44:34PM +0800, Jason Wang wrote: >> On 2020/1/19 =E4=B8=8B=E5=8D=885:59, Michael S. Tsirkin wrote: >>> On Sun, Jan 19, 2020 at 09:07:09AM +0000, Shahaf Shuler wrote: >>>>> Technically, we can keep the incremental API >>>>> here and let the vendor vDPA drivers to record the full mapping >>>>> internally which may slightly increase the complexity of vendor dri= ver. >>>> What will be the trigger for the driver to know it received the last= mapping on this series and it can now push it to the on-chip IOMMU? >>> Some kind of invalidate API? >>> >> The problem is how to deal with the case of vIOMMU. When vIOMMU is ena= bling >> there's no concept of last mapping. >> >> Thanks > Most IOMMUs have a translation cache so have an invalidate API too. Ok, then I get you. But in this case, when vIOMMU is enabled, each new map became a "last=20 mapping". Thanks >