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

Paolo Bonzini
2021-08-11T13:10:52Z

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.

Paolo