linux-kernel - [PATCH v2 0/3] KVM: Properly account for guest CPU time

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Message-Id: <1618298169-3831-1-git-send-email-wanpengli@tencent.com>
Date:   Tue, 13 Apr 2021 15:16:06 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Michael Tokarev <mjt@....msk.ru>
Subject: [PATCH v2 0/3] KVM: Properly account for guest CPU time

The bugzilla https://bugzilla.kernel.org/show_bug.cgi?id=209831
reported that the guest time remains 0 when running a while true
loop in the guest.

The commit 87fa7f3e98a131 ("x86/kvm: Move context tracking where it
belongs") moves guest_exit_irqoff() close to vmexit breaks the
tick-based time accouting when the ticks that happen after IRQs are
disabled are incorrectly accounted to the host/system time. This is
because we exit the guest state too early.

This patchset splits both context tracking logic and the time accounting 
logic from guest_enter/exit_irqoff(), keep context tracking around the 
actual vmentry/exit code, have the virt time specific helpers which 
can be placed at the proper spots in kvm. In addition, it will not 
break the world outside of x86.

v1 -> v2:
 * split context_tracking from guest_enter/exit_irqoff
 * provide separate vtime accounting functions for consistent
 * place the virt time specific helpers at the proper splot 

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Sean Christopherson <seanjc@...gle.com>
Cc: Michael Tokarev <mjt@....msk.ru>

Wanpeng Li (3):
  context_tracking: Split guest_enter/exit_irqoff
  context_tracking: Provide separate vtime accounting functions
  x86/kvm: Fix vtime accounting

 arch/x86/kvm/svm/svm.c           |  6 ++-
 arch/x86/kvm/vmx/vmx.c           |  6 ++-
 arch/x86/kvm/x86.c               |  1 +
 include/linux/context_tracking.h | 84 +++++++++++++++++++++++++++++++---------
 4 files changed, 74 insertions(+), 23 deletions(-)

-- 
2.7.4