On Mon, May 04, 2020 at 09:20:05PM +0200, Paolo Bonzini wrote: > On 04/05/20 20:55, Peter Xu wrote: > > On Mon, May 04, 2020 at 11:55:55AM -0400, Paolo Bonzini wrote: > >> The purpose of this series is to get rid of the get_dr6 accessor > >> and, on Intel, of set_dr6 as well. This is done mostly in patch 2, > >> since patch 3 is only the resulting cleanup. Patch 1 is a related > >> bug fix that I found while inspecting the code. > > > > Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> > > > > (Btw, the db_interception() change in patch 2 seems to be a real fix to me) > > It should be okay because vcpu->arch.dr6 is not used on AMD. > > However I think a kvm_update_dr6 call is missing in > kvm_deliver_exception_payload, and kvm_vcpu_check_breakpoint should use > kvm_queue_exception_p. Seems correct. Maybe apply the same thing to handle_exception_nmi() and handle_dr()? It's probably not a problem because VMX does not have set_dr6(), however it's still cleaner to avoid clearing DR_TRAP_BITS and set DR6_RTM manually before calling kvm_queue_exception() every time in VMX code. > I'll fix all of those. > > > I have that in my list, but I don't know it's "sorely" needed. :) It was low > > after I knew the fact that we've got one test in kvm-unit-test, but I can for > > sure do that earlier. > > > > I am wondering whether we still want a test in selftests if there's a similar > > test in kvm-unit-test already. For this one I guess at least the guest debug > > test is still missing. > > The guest debugging test would basically cover the gdbstub case, which > is different from kvm-unit-tests. It would run similar tests to > kvm-unit-tests, but #DB and #BP exceptions would be replaced by > KVM_EXIT_DEBUG, and MOVs to DR would be replaced by KVM_SET_GUEST_DEBUG. > > It could also cover exception payload support in KVM_GET_VCPU_EVENTS, > but that is more complicated because it would require support for > exceptions in the selftests. Yep, I guess the in-guest debug test will still need the exception support, though I also guess we don't need that when we have the kvm unit test, and anyway I'll start with the simple (KVM_SET_GUEST_DEBUG). Thanks, -- Peter Xu
