On Tue, Sep 01, 2020 at 12:36:40PM +0200, Vitaly Kuznetsov wrote: > Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes: > > > On Mon, Aug 24, 2020 at 03:45:26PM -0700, Jim Mattson wrote: > >> On Mon, Aug 24, 2020 at 11:57 AM Jim Mattson <jmattson@xxxxxxxxxx> wrote: > >> > > >> > On Fri, Aug 21, 2020 at 8:40 PM Sean Christopherson > >> > <sean.j.christopherson@xxxxxxxxx> wrote: > >> > > I agree the code is a mess (kvm_init() and kvm_exit() included), but I'm > >> > > pretty sure hardware_disable_nolock() is guaranteed to be a nop as it's > >> > > impossible for kvm_usage_count to be non-zero if vmx_init() hasn't > >> > > finished. > >> > > >> > Unless I'm missing something, there's no check for a non-zero > >> > kvm_usage_count on this path. There is such a check in > >> > hardware_disable_all_nolock(), but not in hardware_disable_nolock(). > >> > >> However, cpus_hardware_enabled shouldn't have any bits set, so > >> everything's fine. Nothing to see here, after all. > > > > Ugh, I forgot that hardware_disable_all_nolock() does a BUG_ON() instead of > > bailing on !kvm_usage_count. > > But we can't hit this BUG_ON(), right? I'm failing to see how > hardware_disable_all_nolock() can be reached with kvm_usage_count==0. Correct, I was mostly talking to myself.
