Paolo Bonzini <pbonzini@xxxxxxxxxx> writes: > On 08/04/21 14:01, Vitaly Kuznetsov wrote: >> >> Also, we can probably defer kvm_hv_hypercall_read_xmm() until we know >> how many regs we actually need to not read them all (we will always >> need xmm[0] I guess so we can as well read it here). > > The cost is get/put FPU, so I think there's not much to gain from that. > Maybe, I just think that in most cases we will only need xmm0. To make the optimization work we can probably do kvm_get_fpu() once we figured out that we're dealing with XMM hypercall and do kvm_put_fpu() when we're done processing hypercall parameters. This way we don't need to do get/put twice. We can certainly leave this idea to the (possible) future optimizations. -- Vitaly
