On Tue, May 25, 2021 at 01:05:51PM -0500, Mike Christie wrote: > The following patches apply over linus's tree or mst's vhost branch > and my cleanup patchset: > > https://lists.linuxfoundation.org/pipermail/virtualization/2021-May/054354.html > > These patches allow us to support multiple vhost workers per device. I > ended up just doing Stefan's original idea where userspace has the > kernel create a worker and we pass back the pid. This has the benefit > over the workqueue and userspace thread approach where we only have > one'ish code path in the kernel during setup to detect old tools. The > main IO paths and device/vq setup/teardown paths all use common code. > > The kernel patches here allow us to then do N workers device and also > share workers across devices. > > I've also included a patch for qemu so you can get an idea of how it > works. If we are ok with the kernel code then I'll break that up into > a patchset and send to qemu-devel. It seems risky to allow userspace process A to "share" a vhost worker thread with userspace process B based on a matching pid alone. Should they have ptrace_may_access() or similar? For example, two competing users could sabotague each other by running lots of work items on their competitor's vhost worker thread.
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