> Subject: Re: question about virtio-vsock on xen > > > > On 26.02.24 05:09, Peng Fan wrote: > > Hi Oleksandr, > > Hello Peng > > > [snip] > > >> > >> ... Peng, we have vhost-vsock (and vhost-net) Xen PoC. Although > >> it is non- upstreamable in its current shape (based on old Linux > >> version, requires some rework and proper integration, most likely > >> requires involving Qemu and protocol changes to pass an additional > >> info to vhost), it works with Linux > >> v5.10 + patched Qemu v7.0, so you can refer to the Yocto meta layer > >> which contains kernel patches for the details [1]. > > > > Thanks for the pointer, I am reading the code. > > > >> > >> In a nutshell, before accessing the guest data the host module needs > >> to map descriptors in virtio rings which contain either guest grant > >> based DMA addresses (by using Xen grant mappings) or guest > >> pseudo-physical addresses (by using Xen foreign mappings). After > >> accessing the guest data the host module needs to unmap them. > > > > Ok, I thought the current xen virtio code already map every ready. > > > > It does, as you said the virtio-blk-pci worked in your environment. But > vhost(-vsock) is a special case, unlike for virtio-blk-pci where the whole > backend resides in Qemu, here we have a split model. As I understand the > Qemu performs only initial setup/configuration then offloads the I/O > processing to a separate entity which is the Linux module in that particular > case.
Thanks for sharing me the information. I need to learn more stuff:) Thanks, Peng.
