From: Wanpeng Li <wanpengli@xxxxxxxxxxx> 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. vtime-based time accounting is tied to context tracking, keep the guest_exit_irqoff() around vmexit code when both vtime-based time accounting and specific cpu is context tracking mode active. Otherwise, leave guest_exit_irqoff() after handle_exit_irqoff() and explicit IRQ window for tick-based time accouting. Fixes: 87fa7f3e98a131 ("x86/kvm: Move context tracking where it belongs") Cc: Sean Christopherson <seanjc@xxxxxxxxxx> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx> --- arch/x86/kvm/svm/svm.c | 3 ++- arch/x86/kvm/vmx/vmx.c | 3 ++- arch/x86/kvm/x86.c | 2 ++ 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 58a45bb..55fb5ce 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3812,7 +3812,8 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, * into world and some more. */ lockdep_hardirqs_off(CALLER_ADDR0); - guest_exit_irqoff(); + if (vtime_accounting_enabled_this_cpu()) + guest_exit_irqoff(); instrumentation_begin(); trace_hardirqs_off_finish(); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 32cf828..85695b3 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6689,7 +6689,8 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu, * into world and some more. */ lockdep_hardirqs_off(CALLER_ADDR0); - guest_exit_irqoff(); + if (vtime_accounting_enabled_this_cpu()) + guest_exit_irqoff(); instrumentation_begin(); trace_hardirqs_off_finish(); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index fe806e8..234c8b3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9185,6 +9185,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) ++vcpu->stat.exits; local_irq_disable(); kvm_after_interrupt(vcpu); + if (!vtime_accounting_enabled_this_cpu()) + guest_exit_irqoff(); if (lapic_in_kernel(vcpu)) { s64 delta = vcpu->arch.apic->lapic_timer.advance_expire_delta; -- 2.7.4
