Messages in this thread | | | Date | Thu, 21 Apr 2022 19:14:20 +0200 | Subject | Re: [PATCH] KVM: x86: add HC_VMM_CUSTOM hypercall | From | Paolo Bonzini <> |
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On 4/21/22 18:51, Peter Oskolkov wrote: > Allow kvm-based VMMs to request KVM to pass a custom vmcall > from the guest to the VMM in the host. > > Quite often, operating systems research projects and/or specialized > paravirtualized workloads would benefit from a extra-low-overhead, > extra-low-latency guest-host communication channel.
You can use a memory page and an I/O port. It should be as fast as a hypercall. You can even change it to use ioeventfd if an asynchronous channel is enough, and then it's going to be less than 1 us latency.
Paolo
> With cloud-hypervisor modified to handle the new hypercall (simply > return the sum of the received arguments), the following function in > guest_userspace_ completes, on average, in 2.5 microseconds (walltime) > on a relatively modern Intel Xeon processor:
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