Re: [RFC PATCH 1/3] kvm: x86: Rename KVM_DEBUGREG_RELOAD to KVM_DEBUGREG_NEED_RELOAD

[Xiaoyao Li]

On 4/27/2020 10:37 PM, Peter Xu wrote:
> On Sat, Apr 25, 2020 at 09:48:17AM +0200, Paolo Bonzini wrote:
> > On 24/04/20 22:21, Peter Xu wrote:
> > > But then shouldn't DIRTY be set as long as KVM_DEBUGREG_BP_ENABLED is set every
> > > time before vmenter?  Then it'll somehow go back to switch_db_regs, iiuc...
> > >
> > > IIUC RELOAD actually wants to say "reload only for this iteration", that's why
> > > it's cleared after each reload.  So maybe...  RELOAD_ONCE?
> > >
> > > (Btw, do we have debug regs tests somewhere no matter inside guest or with
> > >   KVM_SET_GUEST_DEBUG?)
> >
> > What about KVM_DEBUGREG_EFF_DB_DIRTY?
>
> The problem is iiuc we always reload eff_db[] no matter which bit in
> switch_db_regs is set, so this may still not clearly identify this bit from the
> rest of the two bits...
>
> Actually I think eff_db[] is a bit confusing here in that it can be either the
> host specified dbreg values or the guest specified depends on the dynamic value
> of KVM_GUESTDBG_USE_HW_BP.
>
> I am thinking maybe it's clearer to have host_db[] and guest_db[], then only
> until vmenter do we load either of them by:

host_db[] is somewhat misleading, how about user_db[] (just like user_fpu)

>    if (KVM_GUESTDBG_USE_HW_BP)
>      load(host_db[]);
>    else
>      load(gueet_db[]);
>
> Then each db[] will be very clear on what's the data is about.  And we don't
> need to check KVM_GUESTDBG_USE_HW_BP every time when accessing eff_db[].