On Intel platforms, the software can use the IA32_MISC_ENABLE[7] bit to
detect whether the processor supports performance monitoring facility.

It depends on the PMU is enabled for the guest, and a software write
operation to this available bit will be ignored. The proposal to ignore
the toggle in KVM is the way to go and that behavior matches bare metal.
Signed-off-by: NLike Xu <likexu@tencent.com>
Message-Id: <20220411101946.20262-5-likexu@tencent.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>