On Thu, Apr 15, 2021 at 03:20:57PM -0700, Sean Christopherson wrote: > This is a continuation of Wanpeng's series[1] to fix tick-based CPU time > accounting on x86, with my cleanups[2] bolted on top. The core premise of > Wanpeng's patches are preserved, but they are heavily stripped down. > Specifically, only the "guest exit" paths are split, and no code is > consolidated. The intent is to do as little as possible in the three > patches that need to be backported. Keeping those changes as small as > possible also meant that my cleanups did not need to unwind much > refactoring. > > On x86, tested CONFIG_VIRT_CPU_ACCOUNTING_GEN =y and =n, and with > CONFIG_DEBUG_ENTRY=y && CONFIG_VALIDATE_STACKS=y. Compile tested arm64, > MIPS, PPC, and s390, the latter with CONFIG_DEBUG_ENTRY=y for giggles. > > One last note: I elected to use vtime_account_guest_exit() in the x86 code > instead of open coding these equivalents: > > if (vtime_accounting_enabled_this_cpu()) > vtime_guest_exit(current); > ... > if (!vtime_accounting_enabled_this_cpu()) > current->flags &= ~PF_VCPU; > > With CONFIG_VIRT_CPU_ACCOUNTING_GEN=n, this is a complete non-issue, but > for the =y case it means context_tracking_enabled_this_cpu() is being > checked back-to-back. The redundant checks bug me, but open coding the > gory details in x86 or providing funky variants in vtime.h felt worse. > > Delta from Wanpeng's v2: > > - s/context_guest/context_tracking_guest, purely to match the existing > functions. I have no strong opinion either way. > - Split only the "exit" functions. > - Partially open code vcpu_account_guest_exit() and > __vtime_account_guest_exit() in x86 to avoid churn when segueing into > my cleanups (see above). > > [1] https://lkml.kernel.org/r/1618298169-3831-1-git-send-email-wanpengli@xxxxxxxxxxx > [2] https://lkml.kernel.org/r/20210413182933.1046389-1-seanjc@xxxxxxxxxx > > Sean Christopherson (6): > sched/vtime: Move vtime accounting external declarations above inlines > sched/vtime: Move guest enter/exit vtime accounting to vtime.h > context_tracking: Consolidate guest enter/exit wrappers > context_tracking: KVM: Move guest enter/exit wrappers to KVM's domain > KVM: x86: Consolidate guest enter/exit logic to common helpers > KVM: Move instrumentation-safe annotations for enter/exit to x86 code > > Wanpeng Li (3): > context_tracking: Move guest exit context tracking to separate helpers > context_tracking: Move guest exit vtime accounting to separate helpers > KVM: x86: Defer tick-based accounting 'til after IRQ handling > > arch/x86/kvm/svm/svm.c | 39 +-------- > arch/x86/kvm/vmx/vmx.c | 39 +-------- > arch/x86/kvm/x86.c | 8 ++ > arch/x86/kvm/x86.h | 52 ++++++++++++ > include/linux/context_tracking.h | 92 ++++----------------- > include/linux/kvm_host.h | 38 +++++++++ > include/linux/vtime.h | 138 +++++++++++++++++++------------ > 7 files changed, 204 insertions(+), 202 deletions(-) Please Cc me on any follow-up of this patchset. I have set up a lot of booby traps on purpose in this cave and I might be able to remember a few on the way. Should you meet one of the poisoned arrows, rest assured that you were not the aimed target though. Thanks.
