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From: Yang Weijiang <weijiang.yang@intel.com>
To: pbonzini@redhat.com, jmattson@google.com, seanjc@google.com,
	vkuznets@redhat.com, wei.w.wang@intel.com,
	like.xu.linux@gmail.com, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: root <root@984fee009f2b.jf.intel.com>
Subject: [PATCH v7 00/15] Introduce Architectural LBR for vPMU
Date: Fri,  6 Aug 2021 15:42:10 +0800	[thread overview]
Message-ID: <1628235745-26566-1-git-send-email-weijiang.yang@intel.com> (raw)

From: root <root@984fee009f2b.jf.intel.com>

The Architectural Last Branch Records (LBRs) is published in the 319433-040
release of Intel Architecture Instruction Set Extensions and Future Features
Programming Reference[0].

The main advantages of Arch LBR are [1]:
- Faster context switching due to XSAVES support and faster reset of
  LBR MSRs via the new DEPTH MSR
- Faster LBR read for a non-PEBS event due to XSAVES support, which
  lowers the overhead of the NMI handler.
- Linux kernel can support the LBR features without knowing the model
  number of the current CPU.

From end user's point of view, the usage of Arch LBR is the same as
the Legacy LBR that has been merged in the mainline.

Note, there's one limitations for current guest Arch LBR implementation:
Guest can only use the same LBR record depth as host, this is due to
the special behavior of MSR_ARCH_LBR_DEPTH: a) On write to the MSR,
it'll reset all Arch LBR recording MSRs to 0s. b) XRSTORS will reset all
recording MSRs to 0s if the saved depth mismatches MSR_ARCH_LBR_DEPTH.

But this limitation won't impact guest perf tool usage.

[0] https://software.intel.com/content/www/us/en/develop/download/intel-architecture-instruction-set-extensions-and-future-features-programming-reference.html
[1] https://lore.kernel.org/lkml/1593780569-62993-1-git-send-email-kan.liang@linux.intel.com/


Previous version:
v6: https://lkml.kernel.org/kvm/1626425406-18582-1-git-send-email-weijiang.yang@intel.com/

Changes in v7:
1. Added fix patch for nested VM entry failure issue, also fix warnings from reported from L1.
2. Added patches to flip LBREn bit upon guest state changes, e.g., on #SMI, #DB, warm reset.
3. Added kvm unit-test application for Arch LBR.
4. Rebased v6 patches to kernel v5.14-rc4.


Like Xu (6):
  perf/x86/intel: Fix the comment about guest LBR support on KVM
  perf/x86/lbr: Simplify the exposure check for the LBR_INFO registers
  KVM: vmx/pmu: Emulate MSR_ARCH_LBR_DEPTH for guest Arch LBR
  KVM: vmx/pmu: Emulate MSR_ARCH_LBR_CTL for guest Arch LBR
  KVM: x86: Refine the matching and clearing logic for supported_xss
  KVM: x86: Add XSAVE Support for Architectural LBR

Sean Christopherson (1):
  KVM: x86: Report XSS as an MSR to be saved if there are supported
    features

Yang Weijiang (8):
  KVM: x86: Add Arch LBR MSRs to msrs_to_save_all list
  KVM: x86/pmu: Refactor code to support guest Arch LBR
  KVM: x86: Refresh CPUID on writes to MSR_IA32_XSS
  KVM: x86/vmx: Check Arch LBR config when return perf capabilities
  KVM: nVMX: Add necessary Arch LBR settings for nested VM
  KVM: x86/vmx: Clear Arch LBREn bit before inject #DB to guest
  KVM: x86/vmx: Flip Arch LBREn bit on guest state change
  KVM: x86/cpuid: Advise Arch LBR feature in CPUID

 arch/x86/events/intel/core.c     |   3 +-
 arch/x86/events/intel/lbr.c      |   6 +-
 arch/x86/include/asm/kvm_host.h  |   1 +
 arch/x86/include/asm/msr-index.h |   1 +
 arch/x86/include/asm/vmx.h       |   4 +
 arch/x86/kvm/cpuid.c             |  54 +++++++++++++-
 arch/x86/kvm/vmx/capabilities.h  |  25 +++++--
 arch/x86/kvm/vmx/nested.c        |   6 +-
 arch/x86/kvm/vmx/pmu_intel.c     | 122 +++++++++++++++++++++++++++----
 arch/x86/kvm/vmx/vmcs12.c        |   1 +
 arch/x86/kvm/vmx/vmcs12.h        |   3 +-
 arch/x86/kvm/vmx/vmx.c           |  54 ++++++++++++--
 arch/x86/kvm/x86.c               |  24 +++++-
 13 files changed, 261 insertions(+), 43 deletions(-)

-- 
2.25.1


             reply	other threads:[~2021-08-06  7:29 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-06  7:42 Yang Weijiang [this message]
2021-08-06  7:42 ` [PATCH v7 01/15] perf/x86/intel: Fix the comment about guest LBR support on KVM Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 02/15] perf/x86/lbr: Simplify the exposure check for the LBR_INFO registers Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 03/15] KVM: x86: Add Arch LBR MSRs to msrs_to_save_all list Yang Weijiang
2021-08-09 13:07   ` Like Xu
2021-08-06  7:42 ` [PATCH v7 04/15] KVM: vmx/pmu: Emulate MSR_ARCH_LBR_DEPTH for guest Arch LBR Yang Weijiang
2021-08-09 13:16   ` Like Xu
2021-08-10  7:38     ` Yang Weijiang
2021-08-10  7:54       ` Like Xu
2021-08-10  9:08         ` Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 05/15] KVM: vmx/pmu: Emulate MSR_ARCH_LBR_CTL " Yang Weijiang
2021-08-06 16:26   ` kernel test robot
2021-08-09 13:36   ` Like Xu
2021-08-10  8:30     ` Yang Weijiang
2021-08-10  8:37       ` Like Xu
2021-08-06  7:42 ` [PATCH v7 06/15] KVM: x86/pmu: Refactor code to support " Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 07/15] KVM: x86: Refresh CPUID on writes to MSR_IA32_XSS Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 08/15] KVM: x86: Report XSS as an MSR to be saved if there are supported features Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 09/15] KVM: x86: Refine the matching and clearing logic for supported_xss Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 10/15] KVM: x86: Add XSAVE Support for Architectural LBR Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 11/15] KVM: x86/vmx: Check Arch LBR config when return perf capabilities Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 12/15] KVM: nVMX: Add necessary Arch LBR settings for nested VM Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 13/15] KVM: x86/vmx: Clear Arch LBREn bit before inject #DB to guest Yang Weijiang
2021-08-09  5:08   ` Like Xu
2021-08-09  9:02     ` Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 14/15] KVM: x86/vmx: Flip Arch LBREn bit on guest state change Yang Weijiang
2021-08-06  7:42 ` [PATCH v7 15/15] KVM: x86/cpuid: Advise Arch LBR feature in CPUID Yang Weijiang

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