On 12/08/21 19:33, Sean Christopherson wrote:
On Thu, Aug 12, 2021, Paolo Bonzini wrote:
On 12/08/21 19:07, Sean Christopherson wrote:
Yeah, I was/am on the fence too, I almost included a blurb in the cover letter
saying as much. I'll do that for v2 and let Paolo decide.
I think it makes sense to have it. You can even use the ternary operator
Hah, yeah, I almost used a ternary op. Honestly don't know why I didn't, guess
my brain flipped a coin.
/*
* When zapping everything, all entries at the top level
* ultimately go away, and the levels below go down with them.
* So do not bother iterating all the way down to the leaves.
The subtle part is that try_step_down() won't actually iterate down because it
explicitly rereads and rechecks the SPTE.
if (iter->level == iter->min_level)
return false;
/*
* Reread the SPTE before stepping down to avoid traversing into page
* tables that are no longer linked from this entry.
*/
iter->old_spte = READ_ONCE(*rcu_dereference(iter->sptep)); \
---> this is the code that is avoided
child_pt = spte_to_child_pt(iter->old_spte, iter->level); /
if (!child_pt)
return false;
Ah, right - so I agree with Ben that it's not too important.
Paolo
