KVM: x86: Only do MSR filtering when access MSR by rdmsr/wrmsr

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2074832



commit ac8d6cad
Author: Hou Wenlong <houwenlong.hwl@antgroup.com>
Date:   Mon Mar 7 20:26:33 2022 +0800

    KVM: x86: Only do MSR filtering when access MSR by rdmsr/wrmsr

    If MSR access is rejected by MSR filtering,
    kvm_set_msr()/kvm_get_msr() would return KVM_MSR_RET_FILTERED,
    and the return value is only handled well for rdmsr/wrmsr.
    However, some instruction emulation and state transition also
    use kvm_set_msr()/kvm_get_msr() to do msr access but may trigger
    some unexpected results if MSR access is rejected, E.g. RDPID
    emulation would inject a #UD but RDPID wouldn't cause a exit
    when RDPID is supported in hardware and ENABLE_RDTSCP is set.
    And it would also cause failure when load MSR at nested entry/exit.
    Since msr filtering is based on MSR bitmap, it is better to only
    do MSR filtering for rdmsr/wrmsr.

Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
    Message-Id: <2b2774154f7532c96a6f04d71c82a8bec7d9e80b.1646655860.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>