On 25/07/2017 06:41, Andi Kleen wrote:
> From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
>
> KVM and perf have a special backdoor mechanism to report the IP for interrupts
> re-executed after vm exit. This works for the NMIs that perf normally uses.
>
> However when perf is in timer mode it doesn't work because the timer interrupt
> doesn't get this special treatment. This is common when KVM is running
> nested in another hypervisor which may not implement the PMU, so only
> timer mode is available.
>
> Call the functions to set up the backdoor IP also for non NMI interrupts.
>
> I renamed the functions to set up the backdoor IP reporting to be more
> appropiate for their new use. The SVM change is only compile tested.
>
> Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> ---
> arch/x86/kvm/svm.c | 6 ++++--
> arch/x86/kvm/vmx.c | 6 ++++--
> arch/x86/kvm/x86.c | 8 ++++----
> arch/x86/kvm/x86.h | 4 ++--
> 4 files changed, 14 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index ba9891ac5c56..41bf6a9de853 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -4872,14 +4872,14 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
> vcpu->arch.regs[VCPU_REGS_RIP] = svm->vmcb->save.rip;
>
> if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
> - kvm_before_handle_nmi(&svm->vcpu);
> + kvm_before_interrupt(&svm->vcpu);
>
> stgi();
>
> /* Any pending NMI will happen here */
>
> if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
> - kvm_after_handle_nmi(&svm->vcpu);
> + kvm_after_interrupt(&svm->vcpu);
>
> sync_cr8_to_lapic(vcpu);
>
> @@ -5234,6 +5234,7 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu,
>
> static void svm_handle_external_intr(struct kvm_vcpu *vcpu)
> {
> + kvm_before_interrupt(vcpu);
> local_irq_enable();
> /*
> * We must have an instruction with interrupts enabled, so
> @@ -5241,6 +5242,7 @@ static void svm_handle_external_intr(struct kvm_vcpu *vcpu)
> */
> asm("nop");
> local_irq_disable();
> + kvm_after_interrupt(vcpu);
> }
Can you do this directly in vcpu_enter_guest?
Maybe you could even inline the functions entirely, setting current_vcpu
right after the local_irq_disable() and clearing it after
kvm_x86_ops->handle_external_intr. This would remove the NMI code in
vmx.c/svm.c, too.
Paolo
> static void svm_sched_in(struct kvm_vcpu *vcpu, int cpu)
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index ca5d2b93385c..a02178914f6c 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -8606,9 +8606,9 @@ static void vmx_complete_atomic_exit(struct vcpu_vmx *vmx)
>
> /* We need to handle NMIs before interrupts are enabled */
> if (is_nmi(exit_intr_info)) {
> - kvm_before_handle_nmi(&vmx->vcpu);
> + kvm_before_interrupt(&vmx->vcpu);
> asm("int $2");
> - kvm_after_handle_nmi(&vmx->vcpu);
> + kvm_after_interrupt(&vmx->vcpu);
> }
> }
>
> @@ -8627,6 +8627,7 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu)
> unsigned long tmp;
> #endif
>
> + kvm_before_interrupt(vcpu);
> vector = exit_intr_info & INTR_INFO_VECTOR_MASK;
> desc = (gate_desc *)vmx->host_idt_base + vector;
> entry = gate_offset(*desc);
> @@ -8650,6 +8651,7 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu)
> [ss]"i"(__KERNEL_DS),
> [cs]"i"(__KERNEL_CS)
> );
> + kvm_after_interrupt(vcpu);
> }
> }
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 0e846f0cb83b..96dae9ca7641 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5975,17 +5975,17 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
> .get_guest_ip = kvm_get_guest_ip,
> };
>
> -void kvm_before_handle_nmi(struct kvm_vcpu *vcpu)
> +void kvm_before_interrupt(struct kvm_vcpu *vcpu)
> {
> __this_cpu_write(current_vcpu, vcpu);
> }
> -EXPORT_SYMBOL_GPL(kvm_before_handle_nmi);
> +EXPORT_SYMBOL_GPL(kvm_before_interrupt);
>
> -void kvm_after_handle_nmi(struct kvm_vcpu *vcpu)
> +void kvm_after_interrupt(struct kvm_vcpu *vcpu)
> {
> __this_cpu_write(current_vcpu, NULL);
> }
> -EXPORT_SYMBOL_GPL(kvm_after_handle_nmi);
> +EXPORT_SYMBOL_GPL(kvm_after_interrupt);
>
> static void kvm_set_mmio_spte_mask(void)
> {
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index 612067074905..adb269538e7c 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -155,8 +155,8 @@ static inline bool kvm_check_has_quirk(struct kvm *kvm, u64 quirk)
> return !(kvm->arch.disabled_quirks & quirk);
> }
>
> -void kvm_before_handle_nmi(struct kvm_vcpu *vcpu);
> -void kvm_after_handle_nmi(struct kvm_vcpu *vcpu);
> +void kvm_before_interrupt(struct kvm_vcpu *vcpu);
> +void kvm_after_interrupt(struct kvm_vcpu *vcpu);
> void kvm_set_pending_timer(struct kvm_vcpu *vcpu);
> int kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip);
>
>
