Re: [PATCH] KVM: X86: Also reload the debug registers before kvm_x86->run() when the host is using them

[Paolo Bonzini]

On 09/07/21 18:35, Jim Mattson wrote:
> > > > Just what you said, it's not easy and the needs are limited.  I
> > > > implemented kvm_vcpu_check_breakpoint because I was interested in
> > > > using hardware breakpoints from gdb, even with unrestricted_guest=0
> > > > and invalid guest state, but that's it.
> > > It seems kvm_vcpu_check_breakpoint() handles only for code breakpoint
> > > and doesn't handle for data breakpoints.
> > Correct, there's a comment above the call.  But data breakpoint are much
> > harder and relatively less useful.
>
> Data breakpoints are actually quite useful. I/O breakpoints not so much.

Normally yes; much less for the specific case of debugging 
invalid-guest-state or other invocations of the emulator.

Paolo