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([2001:b07:6468:f312:63a7:c72e:ea0e:6045]) by smtp.gmail.com with ESMTPSA id go17sm920469ejc.76.2021.11.11.00.24.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 11 Nov 2021 00:24:01 -0800 (PST) Message-ID: Date: Thu, 11 Nov 2021 09:24:00 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [RFC] hypercall-vsock: add a new vsock transport Content-Language: en-US To: "Wang, Wei W" , Stefano Garzarella Cc: "davem@davemloft.net" , "kuba@kernel.org" , Stefan Hajnoczi , "mst@redhat.com" , "kys@microsoft.com" , "linux-kernel@vger.kernel.org" , "virtualization@lists.linux-foundation.org" , "Yamahata, Isaku" , "Nakajima, Jun" , "Kleen, Andi" , Andra Paraschiv , Sergio Lopez Pascual References: <71d7b0463629471e9d4887d7fcef1d8d@intel.com> <20211110111718.5cvt6vgory3fzqld@steredhat> <9901a74b149d4245b0e6c998b5cde7af@intel.com> From: Paolo Bonzini In-Reply-To: <9901a74b149d4245b0e6c998b5cde7af@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/11/21 09:14, Wang, Wei W wrote: >> Adding Andra and Sergio, because IIRC Firecracker and libkrun >> emulates virtio-vsock with virtio-mmio so the implementation >> should be simple and also not directly tied to a specific VMM. >> > OK. This would be OK for KVM based guests. For Hyperv and VMWare > based guests, they don't have virtio-mmio support. If the MigTD (a > special guest) we provide is based on virtio-mmio, it would not be > usable to them. Hyper-V and VMware (and KVM) would have to add support for hypercall-vsock anyway. Why can't they just implement a subset of virtio-mmio? It's not hard and there's even plenty of permissively- licensed code in the various VMMs for the *BSDs. In fact, instead of defining your own transport for vsock, my first idea would have been the opposite: reuse virtio-mmio for the registers and the virtqueue format, and define your own virtio device for the MigTD! Thanks, Paolo