On Mon, 2018-08-27 at 19:10 -0700, Andy Lutomirski wrote: > On Mon, Aug 27, 2018 at 6:31 PM, Rik van Riel <riel@xxxxxxxxxxx> > wrote: > > > What is special about this path wrt nmi_uaccess_ok that is > > not also true for the need_flush branch right above it? > > > > What am I missing? > > Nothing. My patch is buggy. ETOLITTLESLEEP. > > I could drop this part of the patch entirely. Or I could drop the > loaded_mm->pgd == __va(read_cr3_pa() check and instead make sure that > loaded_mm is NULL at any point at which loaded_mm might not match > CR3. > The latter will be faster in any (hypothetical) virtualization > environment where CR3 reads trap. I don't know if we have any such > cases where perf works and we care about performance, though. Moving that loaded_mm = NULL assignment up a few lines, so it comes before the "if (need_flush)" test and covers both branches should cover that, indeed. -- All Rights Reversed.
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