On Wed, Oct 19, 2022 at 5:12 PM Xuan Zhuo <[email protected]> wrote: > > On Wed, 19 Oct 2022 17:08:29 +0800, Jason Wang <[email protected]> wrote: > > On Wed, Oct 19, 2022 at 4:21 PM Dust Li <[email protected]> wrote: > > > > > > On Wed, Oct 19, 2022 at 04:03:42PM +0800, Gerry wrote: > > > > > > > > > > > >> 2022年10月19日 16:01，Jason Wang <[email protected]> 写道： > > > >> > > > >> On Wed, Oct 19, 2022 at 3:00 PM Xuan Zhuo <[email protected]> > > > >> wrote: > > > >>> > > > >>> On Tue, 18 Oct 2022 14:54:22 +0800, Jason Wang <[email protected]> > > > >>> wrote: > > > >>>> On Mon, Oct 17, 2022 at 8:31 PM Xuan Zhuo > > > >>>> <[email protected]> wrote: > > > >>>>> > > > >>>>> On Mon, 17 Oct 2022 16:17:31 +0800, Jason Wang > > > >>>>> <[email protected]> wrote: > > > >>>>>> Adding Stefan. > > > >>>>>> > > > >>>>>> > > > >>>>>> On Mon, Oct 17, 2022 at 3:47 PM Xuan Zhuo > > > >>>>>> <[email protected]> wrote: > > > >>>>>>> > > > >>>>>>> Hello everyone, > > > >>>>>>> > > > >>>>>>> # Background > > > >>>>>>> > > > >>>>>>> Nowadays, there is a common scenario to accelerate communication > > > >>>>>>> between > > > >>>>>>> different VMs and containers, including light weight virtual > > > >>>>>>> machine based > > > >>>>>>> containers. One way to achieve this is to colocate them on the > > > >>>>>>> same host. > > > >>>>>>> However, the performance of inter-VM communication through > > > >>>>>>> network stack is not > > > >>>>>>> optimal and may also waste extra CPU cycles. This scenario has > > > >>>>>>> been discussed > > > >>>>>>> many times, but still no generic solution available [1] [2] [3]. > > > >>>>>>> > > > >>>>>>> With pci-ivshmem + SMC(Shared Memory Communications: [4]) based > > > >>>>>>> PoC[5], > > > >>>>>>> We found that by changing the communication channel between VMs > > > >>>>>>> from TCP to SMC > > > >>>>>>> with shared memory, we can achieve superior performance for a > > > >>>>>>> common > > > >>>>>>> socket-based application[5]: > > > >>>>>>> - latency reduced by about 50% > > > >>>>>>> - throughput increased by about 300% > > > >>>>>>> - CPU consumption reduced by about 50% > > > >>>>>>> > > > >>>>>>> Since there is no particularly suitable shared memory management > > > >>>>>>> solution > > > >>>>>>> matches the need for SMC(See ## Comparison with existing > > > >>>>>>> technology), and virtio > > > >>>>>>> is the standard for communication in the virtualization world, we > > > >>>>>>> want to > > > >>>>>>> implement a virtio-ism device based on virtio, which can support > > > >>>>>>> on-demand > > > >>>>>>> memory sharing across VMs, containers or VM-container. To match > > > >>>>>>> the needs of SMC, > > > >>>>>>> the virtio-ism device need to support: > > > >>>>>>> > > > >>>>>>> 1. Dynamic provision: shared memory regions are dynamically > > > >>>>>>> allocated and > > > >>>>>>> provisioned. > > > >>>>>>> 2. Multi-region management: the shared memory is divided into > > > >>>>>>> regions, > > > >>>>>>> and a peer may allocate one or more regions from the same > > > >>>>>>> shared memory > > > >>>>>>> device. > > > >>>>>>> 3. Permission control: The permission of each region can be set > > > >>>>>>> seperately. > > > >>>>>> > > > >>>>>> Looks like virtio-ROCE > > > >>>>>> > > > >>>>>> https://lore.kernel.org/all/[email protected]/T/ > > > >>>>>> > > > >>>>>> and virtio-vhost-user can satisfy the requirement? > > > >>>>>> > > > >>>>>>> > > > >>>>>>> # Virtio ism device > > > >>>>>>> > > > >>>>>>> ISM devices provide the ability to share memory between different > > > >>>>>>> guests on a > > > >>>>>>> host. A guest's memory got from ism device can be shared with > > > >>>>>>> multiple peers at > > > >>>>>>> the same time. This shared relationship can be dynamically > > > >>>>>>> created and released. > > > >>>>>>> > > > >>>>>>> The shared memory obtained from the device is divided into > > > >>>>>>> multiple ism regions > > > >>>>>>> for share. ISM device provides a mechanism to notify other ism > > > >>>>>>> region referrers > > > >>>>>>> of content update events. > > > >>>>>>> > > > >>>>>>> # Usage (SMC as example) > > > >>>>>>> > > > >>>>>>> Maybe there is one of possible use cases: > > > >>>>>>> > > > >>>>>>> 1. SMC calls the interface ism_alloc_region() of the ism driver > > > >>>>>>> to return the > > > >>>>>>> location of a memory region in the PCI space and a token. > > > >>>>>>> 2. The ism driver mmap the memory region and return to SMC with > > > >>>>>>> the token > > > >>>>>>> 3. SMC passes the token to the connected peer > > > >>>>>>> 3. the peer calls the ism driver interface > > > >>>>>>> ism_attach_region(token) to > > > >>>>>>> get the location of the PCI space of the shared memory > > > >>>>>>> > > > >>>>>>> > > > >>>>>>> # About hot plugging of the ism device > > > >>>>>>> > > > >>>>>>> Hot plugging of devices is a heavier, possibly failed, > > > >>>>>>> time-consuming, and > > > >>>>>>> less scalable operation. So, we don't plan to support it for > > > >>>>>>> now. > > > >>>>>>> > > > >>>>>>> # Comparison with existing technology > > > >>>>>>> > > > >>>>>>> ## ivshmem or ivshmem 2.0 of Qemu > > > >>>>>>> > > > >>>>>>> 1. ivshmem 1.0 is a large piece of memory that can be seen by > > > >>>>>>> all devices that > > > >>>>>>> use this VM, so the security is not enough. > > > >>>>>>> > > > >>>>>>> 2. ivshmem 2.0 is a shared memory belonging to a VM that can be > > > >>>>>>> read-only by all > > > >>>>>>> other VMs that use the ivshmem 2.0 shared memory device, which > > > >>>>>>> also does not > > > >>>>>>> meet our needs in terms of security. > > > >>>>>>> > > > >>>>>>> ## vhost-pci and virtiovhostuser > > > >>>>>>> > > > >>>>>>> Does not support dynamic allocation and therefore not suitable > > > >>>>>>> for SMC. > > > >>>>>> > > > >>>>>> I think this is an implementation issue, we can support VHOST IOTLB > > > >>>>>> message then the regions could be added/removed on demand. > > > >>>>> > > > >>>>> > > > >>>>> 1. After the attacker connects with the victim, if the attacker > > > >>>>> does not > > > >>>>> dereference memory, the memory will be occupied under > > > >>>>> virtiovhostuser. In the > > > >>>>> case of ism devices, the victim can directly release the > > > >>>>> reference, and the > > > >>>>> maliciously referenced region only occupies the attacker's > > > >>>>> resources > > > >>>> > > > >>>> Let's define the security boundary here. E.g do we trust the device > > > >>>> or > > > >>>> not? If yes, in the case of virtiovhostuser, can we simple do > > > >>>> VHOST_IOTLB_UNMAP then we can safely release the memory from the > > > >>>> attacker. > > > >>>> > > > >>>>> > > > >>>>> 2. The ism device of a VM can be shared with multiple (1000+) VMs > > > >>>>> at the same > > > >>>>> time, which is a challenge for virtiovhostuser > > > >>>> > > > >>>> Please elaborate more the the challenges, anything make > > > >>>> virtiovhostuser different? > > > >>> > > > >>> I understand (please point out any mistakes), one vvu device > > > >>> corresponds to one > > > >>> vm. If we share memory with 1000 vm, do we have 1000 vvu devices? > > > >> > > > >> There could be some misunderstanding here. With 1000 VM, you still > > > >> need 1000 virtio-sim devices I think. > > > >We are trying to achieve one virtio-ism device per vm instead of one > > > >virtio-ism device per SMC connection. > > > > I wonder if we need something to identify a virtio-ism device since I > > guess there's still a chance to have multiple virtio-ism device per VM > > (different service chain etc). > > Yes, there will be such a situation, a vm has multiple virtio-ism devices. > > What exactly do you mean by "identify"?
E.g we can differ two virtio-net through mac address, do we need something similar for ism, or it's completely unncessary (e.g via token or other) ? Thanks > > Thanks. > > > > > > Thanks > > > > > > > > I think we must achieve this if we want to meet the requirements of SMC. > > > In SMC, a SMC socket(Corresponding to a TCP socket) need 2 memory > > > regions(1 for Tx and 1 for Rx). So if we have 1K TCP connections, > > > we'll need 2K share memory regions, and those memory regions are > > > dynamically allocated and freed with the TCP socket. > > > > > > > > > > >> > > > >>> > > > >>> > > > >>>> > > > >>>>> > > > >>>>> 3. The sharing relationship of ism is dynamically increased, and > > > >>>>> virtiovhostuser > > > >>>>> determines the sharing relationship at startup. > > > >>>> > > > >>>> Not necessarily with IOTLB API? > > > >>> > > > >>> Unlike virtio-vhost-user, which shares the memory of a vm with > > > >>> another vm, we > > > >>> provide the same memory on the host to two vms. So the implementation > > > >>> of this > > > >>> part will be much simpler. This is why we gave up virtio-vhost-user > > > >>> at the > > > >>> beginning. > > > >> > > > >> Ok, just to make sure we're at the same page. From spec level, > > > >> virtio-vhost-user doesn't (can't) limit the backend to be implemented > > > >> in another VM. So it should be ok to be used for sharing memory > > > >> between a guest and host. > > > >> > > > >> Thanks > > > >> > > > >>> > > > >>> Thanks. > > > >>> > > > >>> > > > >>>> > > > >>>>> > > > >>>>> 4. For security issues, the device under virtiovhostuser may mmap > > > >>>>> more memory, > > > >>>>> while ism only maps one region to other devices > > > >>>> > > > >>>> With VHOST_IOTLB_MAP, the map could be done per region. > > > >>>> > > > >>>> Thanks > > > >>>> > > > >>>>> > > > >>>>> Thanks. > > > >>>>> > > > >>>>>> > > > >>>>>> Thanks > > > >>>>>> > > > >>>>>>> > > > >>>>>>> # Design > > > >>>>>>> > > > >>>>>>> This is a structure diagram based on ism sharing between two > > > >>>>>>> vms. > > > >>>>>>> > > > >>>>>>> > > > >>>>>>> |-------------------------------------------------------------------------------------------------------------| > > > >>>>>>> | |------------------------------------------------| > > > >>>>>>> |------------------------------------------------| | > > > >>>>>>> | | Guest | | > > > >>>>>>> Guest | | > > > >>>>>>> | | | | > > > >>>>>>> | | > > > >>>>>>> | | ---------------- | | > > > >>>>>>> ---------------- | | > > > >>>>>>> | | | driver | [M1] [M2] [M3] | | > > > >>>>>>> | driver | [M2] [M3] | | > > > >>>>>>> | | ---------------- | | | | | > > > >>>>>>> ---------------- | | | | > > > >>>>>>> | | |cq| |map |map |map | | > > > >>>>>>> |cq| |map |map | | > > > >>>>>>> | | | | | | | | | > > > >>>>>>> | | | | | | > > > >>>>>>> | | | | ------------------- | | > > > >>>>>>> | | -------------------- | | > > > >>>>>>> | |----|--|----------------| device memory |-----| > > > >>>>>>> |----|--|----------------| device memory |----| | > > > >>>>>>> | | | | ------------------- | | > > > >>>>>>> | | -------------------- | | > > > >>>>>>> | | | | | > > > >>>>>>> | | | > > > >>>>>>> | | | | | > > > >>>>>>> | | | > > > >>>>>>> | | Qemu | | | > > > >>>>>>> Qemu | | | > > > >>>>>>> | |--------------------------------+---------------| > > > >>>>>>> |-------------------------------+----------------| | > > > >>>>>>> | | > > > >>>>>>> | | > > > >>>>>>> | | > > > >>>>>>> | | > > > >>>>>>> | > > > >>>>>>> |------------------------------+------------------------| > > > >>>>>>> | > > > >>>>>>> | > > > >>>>>>> | | > > > >>>>>>> | > > > >>>>>>> | | > > > >>>>>>> | > > > >>>>>>> -------------------------- | > > > >>>>>>> | | M1 | > > > >>>>>>> | M2 | | M3 | | > > > >>>>>>> | > > > >>>>>>> -------------------------- | > > > >>>>>>> | > > > >>>>>>> | > > > >>>>>>> | HOST > > > >>>>>>> | > > > >>>>>>> > > > >>>>>>> --------------------------------------------------------------------------------------------------------------- > > > >>>>>>> > > > >>>>>>> # POC code > > > >>>>>>> > > > >>>>>>> Kernel: > > > >>>>>>> https://github.com/fengidri/linux-kernel-virtio-ism/commits/ism > > > >>>>>>> Qemu: https://github.com/fengidri/qemu/commits/ism > > > >>>>>>> > > > >>>>>>> If there are any problems, please point them out. > > > >>>>>>> > > > >>>>>>> Hope to hear from you, thank you. > > > >>>>>>> > > > >>>>>>> [1] > > > >>>>>>> https://projectacrn.github.io/latest/tutorials/enable_ivshmem.html > > > >>>>>>> [2] https://dl.acm.org/doi/10.1145/2847562 > > > >>>>>>> [3] https://hal.archives-ouvertes.fr/hal-00368622/document > > > >>>>>>> [4] https://lwn.net/Articles/711071/ > > > >>>>>>> [5] > > > >>>>>>> https://lore.kernel.org/netdev/[email protected]/T/ > > > >>>>>>> > > > >>>>>>> > > > >>>>>>> Xuan Zhuo (2): > > > >>>>>>> Reserve device id for ISM device > > > >>>>>>> virtio-ism: introduce new device virtio-ism > > > >>>>>>> > > > >>>>>>> content.tex | 3 + > > > >>>>>>> virtio-ism.tex | 340 > > > >>>>>>> +++++++++++++++++++++++++++++++++++++++++++++++++ > > > >>>>>>> 2 files changed, 343 insertions(+) > > > >>>>>>> create mode 100644 virtio-ism.tex > > > >>>>>>> > > > >>>>>>> -- > > > >>>>>>> 2.32.0.3.g01195cf9f > > > >>>>>>> > > > >>>>>>> > > > >>>>>>> --------------------------------------------------------------------- > > > >>>>>>> To unsubscribe, e-mail: > > > >>>>>>> [email protected] > > > >>>>>>> For additional commands, e-mail: > > > >>>>>>> [email protected] > > > >>>>>>> > > > >>>>>> > > > >>>>> > > > >>>>> --------------------------------------------------------------------- > > > >>>>> To unsubscribe, e-mail: [email protected] > > > >>>>> For additional commands, e-mail: > > > >>>>> [email protected] > > > >>>>> > > > >>>> > > > >>> > > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [email protected] > For additional commands, e-mail: [email protected] > --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
