There is no need to store the page pointers simply to transcribe the same
information into iov later. Drop the guest_data intermediate array.
These days, linux has a maximum limit of 1024 iovs. Libc under the hood will
subdivide the submission if necessary, which is why our general case of 1026
submissions works.
xenforeignmemory_map() maps the requested guest memory contiguously, and
except for PV pagetable frames, we submit contiguously into the stream. When
safe to do, merge adjacent vectors by extending iov_len, reducing the
likelihood that libc needs to subdivide the submission.
Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Frediano Ziglio
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