From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 5/5] virtio: Add bounce DMA ops Date: Wed, 29 Apr 2020 05:52:05 -0400 Message-ID: <20200429055125-mutt-send-email-mst@kernel.org> References: <1588073958-1793-1-git-send-email-vatsa@codeaurora.org> <1588073958-1793-6-git-send-email-vatsa@codeaurora.org> <20200428121232-mutt-send-email-mst@kernel.org> <20200428174952.GA5097@quicinc.com> <20200428163448-mutt-send-email-mst@kernel.org> <275eba4b-dd35-aa95-b2e3-9c5cbf7c6d71@linux.intel.com> <20200429004531-mutt-send-email-mst@kernel.org> <20200429023842-mutt-send-email-mst@kernel.org> <20200429094410.GD5097@quicinc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Return-path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: In-Reply-To: <20200429094410.GD5097@quicinc.com> Content-Disposition: inline To: Srivatsa Vaddagiri Cc: Lu Baolu , tsoni@codeaurora.org, virtio-dev@lists.oasis-open.org, konrad.wilk@oracle.com, jan.kiszka@siemens.com, jasowang@redhat.com, christoffer.dall@arm.com, virtualization@lists.linux-foundation.org, alex.bennee@linaro.org, iommu@lists.linux-foundation.org, stefano.stabellini@xilinx.com, will@kernel.org, linux-kernel@vger.kernel.org, pratikp@codeaurora.org List-Id: virtualization@lists.linuxfoundation.org On Wed, Apr 29, 2020 at 03:14:10PM +0530, Srivatsa Vaddagiri wrote: > * Michael S. Tsirkin [2020-04-29 02:50:41]: >=20 > > So it seems that with modern Linux, all one needs > > to do on x86 is mark the device as untrusted. > > It's already possible to do this with ACPI and with OF - would that be > > sufficient for achieving what this patchset is trying to do? >=20 > In my case, its not sufficient to just mark virtio device untrusted and t= hus > activate the use of swiotlb. All of the secondary VM memory, including th= ose > allocate by swiotlb driver, is private to it. So why not make the bounce buffer memory shared then? > An additional piece of memory is > available to secondary VM which is shared between VMs and which is where = I need > swiotlb driver to do its work. >=20 > --=20 > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member > of Code Aurora Forum, hosted by The Linux Foundation