linux-kernel - [PATCH v2 0/6] kvm: x86: export TSC information to user-space

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Date:   Fri, 16 Sep 2016 10:27:30 -0400
From:   Luiz Capitulino <lcapitulino@...hat.com>
To:     kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, pbonzini@...hat.com,
        rkrcmar@...hat.com, rostedt@...dmis.org, mhiramat@...nel.org,
        mtosatti@...hat.com
Subject: [PATCH v2 0/6] kvm: x86: export TSC information to user-space

[Introduction will follow]

Changelog
---------

v2

 - add tsc_offset field to struct kvm_vcpu_arch
 - drop read_tsc_offset()
 - add per-vcpu dir entries in debugfs
 - export TSC scaling info (besides TSC offset)
 - export the TSC offset as a signed number
 - drop patch that wrongly tried to improve error
   handling in kvm_create_vm_debugfs()

Intro
-----

This series exports a VM's TSC offset and TSC scaling
information to user-space via a new per-vcpu directory
in debugfs. For example:

  /sys/kernel/debug/kvm/66828-10/vcpu0/tsc-offset
  /sys/kernel/debug/kvm/66828-10/vcpu0/tsc-scaling-ratio
  /sys/kernel/debug/kvm/66828-10/vcpu0/tsc-scaling-ratio-frac-bits

The TSC offset in particular is needed in user-space
in order for tracing tools, such as trace-cmd, to be
able to merge the host and guest traces using the
host TSC. This is explained in detail in this thread:

  [Qemu-devel] [RFC] host and guest kernel trace merging
  https://lists.nongnu.org/archive/html/qemu-devel/2016-03/msg00887.html

Luiz Capitulino (6):
  kvm: x86: add tsc_offset field to struct kvm_vcpu_arch
  kvm: x86: drop read_tsc_offset()
  kvm: kvm_destroy_vm_debugfs(): check debugfs_stat_data pointer
  kvm: add stubs for arch specific debugfs support
  kvm: create per-vcpu dirs in debugfs
  kvm: x86: export TSC information to user-space

 arch/arm/kvm/arm.c              | 10 ++++++
 arch/mips/kvm/mips.c            | 10 ++++++
 arch/powerpc/kvm/powerpc.c      | 10 ++++++
 arch/s390/kvm/kvm-s390.c        | 10 ++++++
 arch/x86/include/asm/kvm_host.h |  2 +-
 arch/x86/kvm/Makefile           |  2 +-
 arch/x86/kvm/debugfs.c          | 69 +++++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/svm.c              |  8 -----
 arch/x86/kvm/vmx.c              |  6 ----
 arch/x86/kvm/x86.c              | 12 +++++--
 include/linux/kvm_host.h        |  4 +++
 virt/kvm/kvm_main.c             | 40 ++++++++++++++++++++++--
 12 files changed, 161 insertions(+), 22 deletions(-)
 create mode 100644 arch/x86/kvm/debugfs.c

-- 
2.5.5