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:
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[].
>
> We have them in kvm-unit-tests for debug regs inside the guest, but no
> selftests covering KVM_SET_GUEST_DEBUG.
I see! Thanks,
--
Peter Xu
