> -----Original Message-----
> From: linux-kernel-ow...@vger.kernel.org
> [mailto:linux-kernel-ow...@vger.kernel.org] On Behalf Of Paolo Bonzini
> Sent: Wednesday, August 05, 2015 11:24 PM
> To: linux-kernel@vger.kernel.org; k...@vger.kernel.org
> Cc: Steve Rutherford; rkrc...@redhat.com
> Subject: [PATCH 5/9] KVM: x86: unify handling of interrupt window
>
> The interrupt window is currently checked twice, once in vmx.c/svm.c and
> once in dm_request_for_irq_injection. The only difference is the extra
> check for kvm_arch_interrupt_allowed in dm_request_for_irq_injection,
> and the different return value (EINTR/KVM_EXIT_INTR for vmx.c/svm.c vs.
> 0/KVM_EXIT_IRQ_WINDOW_OPEN for dm_request_for_irq_injection).
>
> However, dm_request_for_irq_injection is basically dead code! Revive it
> by removing the checks in vmx.c and svm.c's vmexit handlers, and
> fixing the returned values for the dm_request_for_irq_injection case.
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> arch/x86/kvm/svm.c | 13 -------------
> arch/x86/kvm/vmx.c | 11 -----------
> arch/x86/kvm/x86.c | 4 ++--
> 3 files changed, 2 insertions(+), 26 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 222439fd73d4..189e46479dd5 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -3396,24 +3396,11 @@ static int msr_interception(struct vcpu_svm
> *svm)
>
> static int interrupt_window_interception(struct vcpu_svm *svm)
> {
> - struct kvm_run *kvm_run = svm->vcpu.run;
> -
> kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
> svm_clear_vintr(svm);
> svm->vmcb->control.int_ctl &= ~V_IRQ_MASK;
> mark_dirty(svm->vmcb, VMCB_INTR);
> ++svm->vcpu.stat.irq_window_exits;
> - /*
> - * If the user space waits to inject interrupts, exit as soon as
> - * possible
> - */
> - if (!lapic_in_kernel(&svm->vcpu) &&
> - kvm_run->request_interrupt_window &&
> - !kvm_cpu_has_interrupt(&svm->vcpu)) {
> - kvm_run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
> - return 0;
> - }
> -
> return 1;
> }
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index ef15dc72284b..4cf25b90dbe0 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -5524,17 +5524,6 @@ static int handle_interrupt_window(struct
> kvm_vcpu *vcpu)
> kvm_make_request(KVM_REQ_EVENT, vcpu);
>
> ++vcpu->stat.irq_window_exits;
> -
> - /*
> - * If the user space waits to inject interrupts, exit as soon as
> - * possible
> - */
> - if (!lapic_in_kernel(vcpu) &&
> - vcpu->run->request_interrupt_window &&
> - !kvm_cpu_has_interrupt(vcpu)) {
> - vcpu->run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
> - return 0;
> - }
> return 1;
> }
Is it possible to adjust the code here and remove the later checking in x86.c?
In that case, we can avoid calling dm_request_for_irq_injection(vcpu) for
VM exit. Basically dm_request_for_irq_injection() did the following
checks:
- The same as in handle_interrupt_window() below:
if (!irqchip_in_kernel(vcpu->kvm) &&
vcpu->run->request_interrupt_window &&
!kvm_cpu_has_interrupt(vcpu))
- kvm_arch_interrupt_allowed(vcpu), in which, most of the conditions
are guaranteed by interrupt window exits, the only one I am not sure
how to handle is ' to_vmx(vcpu)->nested.nested_run_pending'.
Thanks,
Feng
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index daa6d4fe97fe..62362fed4169 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6475,8 +6475,8 @@ static int vcpu_run(struct kvm_vcpu *vcpu)
> kvm_inject_pending_timer_irqs(vcpu);
>
> if (dm_request_for_irq_injection(vcpu)) {
> - r = -EINTR;
> - vcpu->run->exit_reason = KVM_EXIT_INTR;
> + r = 0;
> + vcpu->run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
> ++vcpu->stat.request_irq_exits;
> break;
> }
> --
> 1.8.3.1
>
>
> --
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