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    Subject[PATCH v6 05/12] KVM: introduce gfn_to_hva_read/kvm_read_hva/kvm_read_hva_atomic
    This set of functions is only used to read data from host space, in the
    later patch, we will only get a readonly hva in gfn_to_hva_read, and
    the function name is a good hint to let gfn_to_hva_read to pair with
    kvm_read_hva()/kvm_read_hva_atomic()

    Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
    ---
    virt/kvm/kvm_main.c | 27 +++++++++++++++++++++++----
    1 files changed, 23 insertions(+), 4 deletions(-)

    diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
    index 543f9b7..6e3ea15 100644
    --- a/virt/kvm/kvm_main.c
    +++ b/virt/kvm/kvm_main.c
    @@ -1002,6 +1002,25 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
    }
    EXPORT_SYMBOL_GPL(gfn_to_hva);

    +/*
    + * 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 __user *hva, int len)
    +{
    + return __copy_from_user(data, hva, len);
    +}
    +
    +static int kvm_read_hva_atomic(void *data, void __user *hva, int len)
    +{
    + return __copy_from_user_inatomic(data, hva, len);
    +}
    +
    int get_user_page_nowait(struct task_struct *tsk, struct mm_struct *mm,
    unsigned long start, int write, struct page **page)
    {
    @@ -1274,10 +1293,10 @@ int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
    int r;
    unsigned long addr;

    - addr = gfn_to_hva(kvm, gfn);
    + addr = gfn_to_hva_read(kvm, gfn);
    if (kvm_is_error_hva(addr))
    return -EFAULT;
    - r = __copy_from_user(data, (void __user *)addr + offset, len);
    + r = kvm_read_hva(data, (void __user *)addr + offset, len);
    if (r)
    return -EFAULT;
    return 0;
    @@ -1312,11 +1331,11 @@ int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
    gfn_t gfn = gpa >> PAGE_SHIFT;
    int offset = offset_in_page(gpa);

    - addr = gfn_to_hva(kvm, gfn);
    + addr = gfn_to_hva_read(kvm, gfn);
    if (kvm_is_error_hva(addr))
    return -EFAULT;
    pagefault_disable();
    - r = __copy_from_user_inatomic(data, (void __user *)addr + offset, len);
    + r = kvm_read_hva_atomic(data, (void __user *)addr + offset, len);
    pagefault_enable();
    if (r)
    return -EFAULT;
    --
    1.7.7.6


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