> @@ -2514,35 +2512,26 @@ static bool hva_to_pfn_fast(unsigned long addr, bool write_fault,
> * The slow path to get the pfn of the specified host virtual address,
> * 1 indicates success, -errno is returned if error is detected.
> */
> -static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
> - bool interruptible, bool *writable, kvm_pfn_t *pfn)
> +static int hva_to_pfn_slow(struct kvm_follow_pfn *foll, kvm_pfn_t *pfn)
> {
> - unsigned int flags = FOLL_HWPOISON;
> + unsigned int flags = FOLL_HWPOISON | FOLL_GET | foll->flags;
> struct page *page;
> int npages;
>
> might_sleep();
>
> - if (writable)
> - *writable = write_fault;
> -
> - if (write_fault)
> - flags |= FOLL_WRITE;
> - if (async)
> - flags |= FOLL_NOWAIT;
> - if (interruptible)
> - flags |= FOLL_INTERRUPTIBLE;
> -
> - npages = get_user_pages_unlocked(addr, 1, &page, flags);
> + npages = get_user_pages_unlocked(foll->hva, 1, &page, flags);
> if (npages != 1)
> return npages;
>
> + foll->writable = (foll->flags & FOLL_WRITE) && foll->allow_write_mapping;
> +
> /* map read fault as writable if possible */
> - if (unlikely(!write_fault) && writable) {
> + if (unlikely(!foll->writable) && foll->allow_write_mapping) {
I guess !foll->writable should be !(foll->flags & FOLL_WRITE) here.
> struct page *wpage;
>
> - if (get_user_page_fast_only(addr, FOLL_WRITE, &wpage)) {
> - *writable = true;
> + if (get_user_page_fast_only(foll->hva, FOLL_WRITE, &wpage)) {
> + foll->writable = true;
> put_page(page);
> page = wpage;
> }
> @@ -2572,23 +2561,23 @@ static int kvm_try_get_pfn(kvm_pfn_t pfn)
> return get_page_unless_zero(page);
> }
>
...
> +kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
> + bool atomic, bool interruptible, bool *async,
> + bool write_fault, bool *writable, hva_t *hva)
> +{
> + kvm_pfn_t pfn;
> + struct kvm_follow_pfn foll = {
> + .slot = slot,
> + .gfn = gfn,
> + .flags = 0,
> + .atomic = atomic,
> + .allow_write_mapping = !!writable,
> + };
> +
> + if (write_fault)
> + foll.flags |= FOLL_WRITE;
> + if (async)
> + foll.flags |= FOLL_NOWAIT;
> + if (interruptible)
> + foll.flags |= FOLL_INTERRUPTIBLE;
> +
> + pfn = __kvm_follow_pfn(&foll);
> + if (pfn == KVM_PFN_ERR_NEEDS_IO) {
Could we just use KVM_PFN_ERR_FAULT and foll.flags here? I.e.,
if (pfn == KVM_PFN_ERR_FAULT && (foll.flags & FOLL_NOWAIT))?
Setting pfn to KVM_PFN_ERR_NEEDS_IO just to indicate an async fault
seems unnecessary.
> + *async = true;
> + pfn = KVM_PFN_ERR_FAULT;
> + }
> + if (hva)
> + *hva = foll.hva;
> + if (writable)
> + *writable = foll.writable;
> + return pfn;
> }
> EXPORT_SYMBOL_GPL(__gfn_to_pfn_memslot);
>
B.R.
Yu
