KVM: x86/vPMU: Forbid reading from MSR_F15H_PERF MSRs when guest doesn't have...

KVM: x86/vPMU: Forbid reading from MSR_F15H_PERF MSRs when guest doesn't have X86_FEATURE_PERFCTR_CORE

MSR_F15H_PERF_CTL0-5, MSR_F15H_PERF_CTR0-5 MSRs have a CPUID bit assigned
to them (X86_FEATURE_PERFCTR_CORE) and when it wasn't exposed to the guest
the correct behavior is to inject #GP an not just return zero.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210329124804.170173-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>