• Sean Christopherson's avatar
    KVM: Add separate helper for putting borrowed reference to kvm · 149487bd
    Sean Christopherson authored
    Add a new helper, kvm_put_kvm_no_destroy(), to handle putting a borrowed
    reference[*] to the VM when installing a new file descriptor fails.  KVM
    expects the refcount to remain valid in this case, as the in-progress
    ioctl() has an explicit reference to the VM.  The primary motiviation
    for the helper is to document that the 'kvm' pointer is still valid
    after putting the borrowed reference, e.g. to document that doing
    mutex(&kvm->lock) immediately after putting a ref to kvm isn't broken.
    
    [*] When exposing a new object to userspace via a file descriptor, e.g.
        a new vcpu, KVM grabs a reference to itself (the VM) prior to making
        the object visible to userspace to avoid prematurely freeing the VM
        in the scenario where userspace immediately closes file descriptor.
    Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
    Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
    149487bd
book3s_64_mmu_hv.c 53.5 KB