• Sean Christopherson's avatar
    KVM: VMX: Convert vcpu_vmx.exit_reason to a union · 8e533240
    Sean Christopherson authored
    Convert vcpu_vmx.exit_reason from a u32 to a union (of size u32).  The
    full VM_EXIT_REASON field is comprised of a 16-bit basic exit reason in
    bits 15:0, and single-bit modifiers in bits 31:16.
    
    Historically, KVM has only had to worry about handling the "failed
    VM-Entry" modifier, which could only be set in very specific flows and
    required dedicated handling.  I.e. manually stripping the FAILED_VMENTRY
    bit was a somewhat viable approach.  But even with only a single bit to
    worry about, KVM has had several bugs related to comparing a basic exit
    reason against the full exit reason store in vcpu_vmx.
    
    Upcoming Intel features, e.g. SGX, will add new modifier bits that can
    be set on more or less any VM-Exit, as opposed to the significantly more
    restricted FAILED_VMENTRY, i.e. correctly handling everything in one-off
    flows isn't scalable.  Tracking exit reason in a union forces code to
    explicitly choose between consuming the full exit reason and the basic
    exit, and is a convenient way to document and access the modifiers.
    
    No functional change intended.
    
    Cc: Xiaoyao Li <xiaoyao.li@intel.com>
    Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
    Signed-off-by: default avatarChenyi Qiang <chenyi.qiang@intel.com>
    Message-Id: <20201106090315.18606-2-chenyi.qiang@intel.com>
    Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
    8e533240
vmx.c 222 KB