linux-kernel - [PATCH v2 0/7] KVM: x86: Tracepoint improvements and fixes

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Date:   Wed, 23 Sep 2020 13:13:42 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/7] KVM: x86: Tracepoint improvements and fixes

Various improvements and fixes for the kvm_entry, kvm_exit and
kvm_nested_vmexit tracepoints.

  1. Capture the guest's RIP during kvm_entry for obvious reasons.

  2. Extend kvm_exit to report the same info as kvm_nested_vmexit, and
     macrofy its definition to reuse it verbatim for nested exits.

  3. Stop passing in params to kvm_nested_vmexit, and instead use the
     same approach (and now code) as kvm_exit where the tracepoint uses a
     dedicated kvm_x86_ops hook to retrieve the info.

  4. Stop reading GUEST_RIP, EXIT_QUAL, INTR_INFO, and ERROR_CODE on
     every VM-Exit from L2 (some of this comes in #3).  This saves ~100
     cycles (150+ with retpolines) on VM-Exits from L2 that are handled
     by L0, e.g. hardware interrupts.

As noted by Vitaly, these changes break trace-cmd[*].  I hereby pinky
swear that, if this series is merged, I will send patches to update
trace-cmd.

[*] git://git.kernel.org/pub/scm/utils/trace-cmd/trace-cmd.git

v2:
  - Fixed some goofs in the changelogs.
  - Rebased to kvm/queue, commit e1ba1a15af73 ("KVM: SVM: Enable INVPCID
    feature on AMD").

Sean Christopherson (7):
  KVM: x86: Add RIP to the kvm_entry, i.e. VM-Enter, tracepoint
  KVM: x86: Read guest RIP from within the kvm_nested_vmexit tracepoint
  KVM: VMX: Add a helper to test for a valid error code given an intr
    info
  KVM: x86: Add intr/vectoring info and error code to kvm_exit
    tracepoint
  KVM: x86: Add macro wrapper for defining kvm_exit tracepoint
  KVM: x86: Use common definition for kvm_nested_vmexit tracepoint
  KVM: nVMX: Read EXIT_QUAL and INTR_INFO only when needed for nested
    exit

 arch/x86/include/asm/kvm_host.h |   7 ++-
 arch/x86/kvm/svm/svm.c          |  16 ++---
 arch/x86/kvm/trace.h            | 107 +++++++++++++-------------------
 arch/x86/kvm/vmx/nested.c       |  14 ++---
 arch/x86/kvm/vmx/vmcs.h         |   7 +++
 arch/x86/kvm/vmx/vmx.c          |  18 +++++-
 arch/x86/kvm/x86.c              |   2 +-
 7 files changed, 86 insertions(+), 85 deletions(-)

-- 
2.28.0