On Thu, Aug 22, 2019 at 07:10:09PM -0700, Sean Christopherson wrote: > Invoke EADD with the userspace source address instead of first copying > the data to a kernel page to avoid the overhead of alloc_page() and > copy_from_user(). > > Remove all pre-validation of TCS pages. The source page is no longer > readily available since it's not copied into the kernel, and validating > the TCS essentially requires accessing the entire page since the vast > majority of the TCS is reserved bytes. Given that userspace can now > cause EADD to fault simply by passing a bad pointer, validating the TCS > to avoid faults on EADD provides little to no value. > > Suggested-by: Andy Lutomirski <luto@xxxxxxxxxx> > Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> I already merged this to my tree but just realized that the commit message does not address why get_user_pages() is no option. /Jarkko
