Re: [PATCH v3 0/6] KVM: my debug patch queue

Maxim Levitsky
2021-08-11T13:23:30Z

On Wed, 2021-08-11 at 15:10 +0200, Paolo Bonzini wrote:
> On 11/08/21 14:29, Maxim Levitsky wrote:
> > Hi!
> >
> > I would like to publish two debug features which were needed for other stuff
> > I work on.
> >
> > One is the reworked lx-symbols script which now actually works on at least
> > gdb 9.1 (gdb 9.2 was reported to fail to load the debug symbols from the kernel
> > for some reason, not related to this patch) and upstream qemu.
> >
> > The other feature is the ability to trap all guest exceptions (on SVM for now)
> > and see them in kvmtrace prior to potential merge to double/triple fault.
> >
> > This can be very useful and I already had to manually patch KVM a few
> > times for this.
> > I will, once time permits, implement this feature on Intel as well.
> >
> > V2:
> >
> > * Some more refactoring and workarounds for lx-symbols script
> >
> > * added KVM_GUESTDBG_BLOCKIRQ flag to enable 'block interrupts on
> > single step' together with KVM_CAP_SET_GUEST_DEBUG2 capability
> > to indicate which guest debug flags are supported.
> >
> > This is a replacement for unconditional block of interrupts on single
> > step that was done in previous version of this patch set.
> > Patches to qemu to use that feature will be sent soon.
> >
> > * Reworked the the 'intercept all exceptions for debug' feature according
> > to the review feedback:
> >
> > - renamed the parameter that enables the feature and
> > moved it to common kvm module.
> > (only SVM part is currently implemented though)
> >
> > - disable the feature for SEV guests as was suggested during the review
> > - made the vmexit table const again, as was suggested in the review as well.
> >
> > V3:
> > * Modified a selftest to cover the KVM_GUESTDBG_BLOCKIRQ
> > * Rebased on kvm/queue
> >
> > Best regards,
> > Maxim Levitsky
> >
> > Maxim Levitsky (6):
> > KVM: SVM: split svm_handle_invalid_exit
> > KVM: x86: add force_intercept_exceptions_mask
> > KVM: SVM: implement force_intercept_exceptions_mask
> > scripts/gdb: rework lx-symbols gdb script
> > KVM: x86: implement KVM_GUESTDBG_BLOCKIRQ
> > KVM: selftests: test KVM_GUESTDBG_BLOCKIRQ
> >
> > Documentation/virt/kvm/api.rst | 1 +
> > arch/x86/include/asm/kvm_host.h | 5 +-
> > arch/x86/include/uapi/asm/kvm.h | 1 +
> > arch/x86/kvm/svm/svm.c | 87 +++++++-
> > arch/x86/kvm/svm/svm.h | 6 +-
> > arch/x86/kvm/x86.c | 12 +-
> > arch/x86/kvm/x86.h | 2 +
> > kernel/module.c | 8 +-
> > scripts/gdb/linux/symbols.py | 203 ++++++++++++------
> > .../testing/selftests/kvm/x86_64/debug_regs.c | 24 ++-
> > 10 files changed, 266 insertions(+), 83 deletions(-)
> >
>
> Queued 1-5-6.
>
> For patches 2 and 3, please add VMX support too.
>
> For patch 4, it's not KVM :) so please submit it separately.

Thanks!

I will do this!

Best regards,
Maxim Levitsky

>
> Paolo
>