From mboxrd@z Thu Jan 1 00:00:00 1970 From: Srivatsa Vaddagiri Subject: Re: [RFC/PATCH 1/1] virtio: Introduce MMIO ops Date: Thu, 30 Apr 2020 16:41:56 +0530 Message-ID: <20200430111156.GI5097@quicinc.com> References: <1588240976-10213-1-git-send-email-vatsa@codeaurora.org> <1588240976-10213-2-git-send-email-vatsa@codeaurora.org> <20200430101431.GD19932@willie-the-truck> <20200430103446.GH5097@quicinc.com> <20200430104149.GG19932@willie-the-truck> Reply-To: Srivatsa Vaddagiri Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Return-path: Content-Disposition: inline In-Reply-To: <20200430104149.GG19932@willie-the-truck> Sender: linux-kernel-owner@vger.kernel.org To: Will Deacon Cc: konrad.wilk@oracle.com, mst@redhat.com, jasowang@redhat.com, jan.kiszka@siemens.com, stefano.stabellini@xilinx.com, iommu@lists.linux-foundation.org, virtualization@lists.linux-foundation.org, virtio-dev@lists.oasis-open.org, tsoni@codeaurora.org, pratikp@codeaurora.org, christoffer.dall@arm.com, alex.bennee@linaro.org, linux-kernel@vger.kernel.org List-Id: virtualization@lists.linuxfoundation.org * Will Deacon [2020-04-30 11:41:50]: > On Thu, Apr 30, 2020 at 04:04:46PM +0530, Srivatsa Vaddagiri wrote: > > If CONFIG_VIRTIO_MMIO_OPS is defined, then I expect this to be unconditionally > > set to 'magic_qcom_ops' that uses hypervisor-supported interface for IO (for > > example: message_queue_send() and message_queue_recevie() hypercalls). > > Hmm, but then how would such a kernel work as a guest under all the > spec-compliant hypervisors out there? Ok I see your point and yes for better binary compatibility, the ops have to be set based on runtime detection of hypervisor capabilities. > > Ok. I guess the other option is to standardize on a new virtio transport (like > > ivshmem2-virtio)? > > I haven't looked at that, but I suppose it depends on what your hypervisor > folks are willing to accomodate. I believe ivshmem2_virtio requires hypervisor to support PCI device emulation (for life-cycle management of VMs), which our hypervisor may not support. A simple shared memory and doorbell or message-queue based transport will work for us. -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation