On Wed, Sep 27, 2023 at 11:31:18AM +0800, Dapeng Mi wrote: > When guest wants to use PERF_METRICS MSR, a virtual metrics event needs > to be created in the perf subsystem so that the guest can have exclusive > ownership of the PERF_METRICS MSR. Urgh, can someone please remind me how all that is supposed to work again? The guest is just a task that wants the event. If the host creates a CPU event, then that gets scheduled with higher priority and the task looses out, no joy. So you cannot guarantee the guest gets anything. That is, I remember we've had this exact problem before, but I keep forgetting how this all is supposed to work. I don't use this virt stuff (and every time I try qemu arguments defeat me and I give up in disgust).
