linux-kernel - [PATCH v3 0/6] KVM: my debug patch queue

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Date:   Wed, 11 Aug 2021 15:29:21 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Kieran Bingham <kbingham@...nel.org>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        Andrew Jones <drjones@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Johannes Berg <johannes.berg@...el.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        "H. Peter Anvin" <hpa@...or.com>, Jessica Yu <jeyu@...nel.org>,
        Jim Mattson <jmattson@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Yang Weijiang <weijiang.yang@...el.com>,
        linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
        linux-kselftest@...r.kernel.org (open list:KERNEL SELFTEST FRAMEWORK),
        linux-doc@...r.kernel.org (open list:DOCUMENTATION),
        Shuah Khan <shuah@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v3 0/6] KVM: my debug patch queue

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(-)

-- 
2.26.3