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    SubjectRe: [PATCH v3 5/6] KVM: introduce gfn_to_hva_read/kvm_read_hva/kvm_read_hva_atomic
    On 06/18/2012 06:16 PM, Avi Kivity wrote:

    > On 06/12/2012 05:48 AM, Xiao Guangrong wrote:
    >> This set of functions is only used to read data from host space, read is
    >> a special case in the later patch
    >>
    >>
    >> +/*
    >> + * The hva returned by this function is only allowed to be read.
    >> + * It should pair with kvm_read_hva() or kvm_read_hva_atomic().
    >> + */
    >> +static unsigned long gfn_to_hva_read(struct kvm *kvm, gfn_t gfn)
    >> +{
    >> + return gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, NULL);
    >> +}
    >> +
    >> +static int kvm_read_hva(void *data, void *hva, int len)
    >> +{
    >> + return __copy_from_user(data, (void __user *)hva, len);
    >> +
    >> +}
    >> +
    >> +static int kvm_read_hva_atomic(void *data, void *hva, int len)
    >> +{
    >> + return __copy_from_user_inatomic(data, (void __user *)hva, len);
    >> +
    >> +}
    >
    > Why cast to __user? Make it __user in the first place.
    >


    Okay.

    > Also these are just simple wrappers, why to them at all?


    For gfn_to_hva_read(), they will call gfn_to_hva_many(...write = false)
    in the later patch.

    For kvm_read_hva() and kvm_read_hva_atomic(), they are pure wrappers,
    i think its name is a good hint to let gfn_to_hva_read to pair with
    kvm_read_hva()/kvm_read_hva_atomic().



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