From f2485b3e0c6c0aa3a9546babc2fad3739e964ebb Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 15 Jun 2016 15:23:11 +0200 Subject: [PATCH] KVM: x86: use guest_exit_irqoff This gains a few clock cycles per vmexit. On Intel there is no need anymore to enable the interrupts in vmx_handle_external_intr, since we are using the "acknowledge interrupt on exit" feature. AMD needs to do that, and must be careful to avoid the interrupt shadow. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm.c | 6 ++++++ arch/x86/kvm/vmx.c | 4 +--- arch/x86/kvm/x86.c | 11 ++--------- 3 files changed, 9 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 5ff2927..5bfdbbf 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -4935,6 +4935,12 @@ out: static void svm_handle_external_intr(struct kvm_vcpu *vcpu) { local_irq_enable(); + /* + * We must have an instruction with interrupts enabled, so + * the timer interrupt isn't delayed by the interrupt shadow. + */ + asm("nop"); + local_irq_disable(); } 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 1b413a52..c1d655c 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -8574,7 +8574,6 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu) "push %[sp]\n\t" #endif "pushf\n\t" - "orl $0x200, (%%" _ASM_SP ")\n\t" __ASM_SIZE(push) " $%c[cs]\n\t" "call *%[entry]\n\t" : @@ -8587,8 +8586,7 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu) [ss]"i"(__KERNEL_DS), [cs]"i"(__KERNEL_CS) ); - } else - local_irq_enable(); + } } static bool vmx_has_high_real_mode_segbase(void) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 618463a..0cc6cf8 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6709,16 +6709,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) ++vcpu->stat.exits; - /* - * We must have an instruction between local_irq_enable() and - * kvm_guest_exit(), so the timer interrupt isn't delayed by - * the interrupt shadow. The stat.exits increment will do nicely. - * But we need to prevent reordering, hence this barrier(): - */ - barrier(); - - guest_exit(); + guest_exit_irqoff(); + local_irq_enable(); preempt_enable(); vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); -- 2.7.4