Messages in this thread | | | Date | Mon, 27 Apr 2020 10:37:32 -0400 | From | Peter Xu <> | Subject | Re: [RFC PATCH 1/3] kvm: x86: Rename KVM_DEBUGREG_RELOAD to KVM_DEBUGREG_NEED_RELOAD |
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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
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