On Fri, Jul 26, 2024 at 12:33:24PM +0530, Srivatsa Vaddagiri wrote: > > Maybe you can give an example for this? We cache the configuration > > space to a faster access to that. > > Yes for the same reason of faster access, we wish to have config information > cached in hypervisor. In case of VDUSE, > > Guest read -> (VM exit) -> VHOST_VDPA_GET_CONFIG -> vduse_vdpa_get_config > > Basically a guest read terminates in host kernel, before resuming. > > In our case, > > Guest read - (VM exit) - Hyp emulates read - (VM resume) > > So a guest read would terminate in hypervisor itself, before it is resumed. > > Without this optimization, guest VCPU would have stalled until VMM in host can > emulate it, which can be long, especially a concern when the read is issued in > hot path (interrupt handler, w/o MSI_X). Instead of optimizing INT#x (which is futile, it's a shared interrupt and will trigger a ton of exits anyway), just enable MSI-X.
