On 18/02/21 19:12, Sean Christopherson wrote:
Yeah, the problem is I don't understand why 06fc7772690d fixed things in 11
year old KVM instead of breaking them, because effectively this patch is
reverting it.
11 year old KVM didn't grab a different VMCB when updating the intercepts, it
had already copied/merged L1's stuff to L0's VMCB, and then updated L0's VMCB
regardless of is_nested().
Ok, so the bug was introduced when adding recalc_intercepts, which threw
away the intercept manipulations that svm_set_cr0 had done in the
meanwhile. That's commit 384c63684397 ("KVM: SVM: Add function to
recalculate intercept masks", 2011-01-12).
That piece of information makes me feel less uneasy about missing
something. recalc_intercepts has been there for a long time, but not as
long as 06fc7772690d.
Paolo
