Re: [PATCH v7 6/7] KVM: VMX: Add the algorithm of deliver posted interrupt

[Gleb Natapov <gleb@redhat.com>]

On Mon, Apr 01, 2013 at 11:32:34AM +0800, Yang Zhang wrote:
> From: Yang Zhang <yang.z.zhang@Intel.com>
> 
> Only deliver the posted interrupt when target vcpu is running
> and there is no previous interrupt pending in pir.
> 
> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
> ---
>  arch/x86/include/asm/kvm_host.h |    2 +
>  arch/x86/kvm/lapic.c            |   13 ++++++++
>  arch/x86/kvm/lapic.h            |    1 +
>  arch/x86/kvm/svm.c              |    6 ++++
>  arch/x86/kvm/vmx.c              |   60 ++++++++++++++++++++++++++++++++++++++-
>  virt/kvm/kvm_main.c             |    1 +
>  6 files changed, 82 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 8e95512..842ea5a 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -704,6 +704,8 @@ struct kvm_x86_ops {
>  	void (*hwapic_isr_update)(struct kvm *kvm, int isr);
>  	void (*load_eoi_exitmap)(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap);
>  	void (*set_virtual_x2apic_mode)(struct kvm_vcpu *vcpu, bool set);
> +	void (*deliver_posted_interrupt)(struct kvm_vcpu *vcpu, int vector);
> +	void (*sync_pir_to_irr)(struct kvm_vcpu *vcpu);
>  	int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
>  	int (*get_tdp_level)(void);
>  	u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 686afee..95e8f4a 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -310,6 +310,19 @@ static u8 count_vectors(void *bitmap)
>  	return count;
>  }
>  
> +void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir)
> +{
> +	u32 i, pir_val;
> +	struct kvm_lapic *apic = vcpu->arch.apic;
> +
> +	for (i = 0; i <= 7; i++) {
> +		pir_val = xchg(&pir[i], 0);
> +		if (pir_val)
> +			*((u32 *)(apic->regs + APIC_IRR + i * 0x10)) |= pir_val;
> +	}
> +}
> +EXPORT_SYMBOL_GPL(kvm_apic_update_irr);
> +
>  static inline int apic_test_and_set_irr(int vec, struct kvm_lapic *apic)
>  {
>  	apic->irr_pending = true;
> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
> index 599076e..16c3949 100644
> --- a/arch/x86/kvm/lapic.h
> +++ b/arch/x86/kvm/lapic.h
> @@ -54,6 +54,7 @@ u64 kvm_lapic_get_base(struct kvm_vcpu *vcpu);
>  void kvm_apic_set_version(struct kvm_vcpu *vcpu);
>  
>  void kvm_apic_update_tmr(struct kvm_vcpu *vcpu, u32 *tmr);
> +void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir);
>  int kvm_apic_match_physical_addr(struct kvm_lapic *apic, u16 dest);
>  int kvm_apic_match_logical_addr(struct kvm_lapic *apic, u8 mda);
>  int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq);
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 2f8fe3f..d6713e1 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -3577,6 +3577,11 @@ static void svm_hwapic_isr_update(struct kvm *kvm, int isr)
>  	return;
>  }
>  
> +static void svm_sync_pir_to_irr(struct kvm_vcpu *vcpu)
> +{
> +	return;
> +}
> +
>  static int svm_nmi_allowed(struct kvm_vcpu *vcpu)
>  {
>  	struct vcpu_svm *svm = to_svm(vcpu);
> @@ -4305,6 +4310,7 @@ static struct kvm_x86_ops svm_x86_ops = {
>  	.vm_has_apicv = svm_vm_has_apicv,
>  	.load_eoi_exitmap = svm_load_eoi_exitmap,
>  	.hwapic_isr_update = svm_hwapic_isr_update,
> +	.sync_pir_to_irr = svm_sync_pir_to_irr,
>  
>  	.set_tss_addr = svm_set_tss_addr,
>  	.get_tdp_level = get_npt_level,
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index edfc87a..690734c 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -380,6 +380,23 @@ struct pi_desc {
>  	} u;
>  } __aligned(64);
>  
> +static bool pi_test_and_set_on(struct pi_desc *pi_desc)
> +{
> +	return test_and_set_bit(POSTED_INTR_ON,
> +			(unsigned long *)&pi_desc->u.control);
> +}
> +
> +static bool pi_test_and_clear_on(struct pi_desc *pi_desc)
> +{
> +	return test_and_clear_bit(POSTED_INTR_ON,
> +			(unsigned long *)&pi_desc->u.control);
> +}
> +
> +static int pi_test_and_set_pir(int vector, struct pi_desc *pi_desc)
> +{
> +	return test_and_set_bit(vector, (unsigned long *)pi_desc->pir);
> +}
> +
>  struct vcpu_vmx {
>  	struct kvm_vcpu       vcpu;
>  	unsigned long         host_rsp;
> @@ -2851,8 +2868,10 @@ static __init int hardware_setup(void)
>  
>  	if (enable_apicv)
>  		kvm_x86_ops->update_cr8_intercept = NULL;
> -	else
> +	else {
>  		kvm_x86_ops->hwapic_irr_update = NULL;
> +		kvm_x86_ops->deliver_posted_interrupt = NULL;
> +	}
>  
>  	if (nested)
>  		nested_vmx_setup_ctls_msrs();
> @@ -3914,6 +3933,43 @@ static int vmx_vm_has_apicv(struct kvm *kvm)
>  }
>  
>  /*
> + * Send interrupt to vcpu via posted interrupt way.
> + * 1. If target vcpu is running(non-root mode), send posted interrupt
> + * notification to vcpu and hardware will sync PIR to vIRR atomically.
> + * 2. If target vcpu isn't running(root mode), kick it to pick up the
> + * interrupt from PIR in next vmentry.
> + */
> +static void vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
> +{
> +	struct vcpu_vmx *vmx = to_vmx(vcpu);
> +	int r;
> +
> +	if (pi_test_and_set_pir(vector, &vmx->pi_desc))
> +		return;
> +
> +	r = pi_test_and_set_on(&vmx->pi_desc);
> +	kvm_make_request(KVM_REQ_EVENT, vcpu);
> +	if (!r && (vcpu->mode == IN_GUEST_MODE)) {
> +		apic->send_IPI_mask(get_cpu_mask(vcpu->cpu),
> +				POSTED_INTR_VECTOR);
> +	} else
> +		kvm_vcpu_kick(vcpu);
> +
> +	return;
> +}
> +
> +static void vmx_sync_pir_to_irr(struct kvm_vcpu *vcpu)
> +{
> +	struct vcpu_vmx *vmx = to_vmx(vcpu);
> +
> +	if (!vmx_vm_has_apicv(vcpu->kvm) ||
If we set kvm_ops->sync_pir_to_irr() to a function that does nothing if
apicv is disabled we can drop this fast path check here.

> +			!pi_test_and_clear_on(&vmx->pi_desc))
> +		return;
> +
> +	kvm_apic_update_irr(vcpu, vmx->pi_desc.pir);
> +}
> +
> +/*
>   * Set up the vmcs's constant host-state fields, i.e., host-state fields that
>   * will not change in the lifetime of the guest.
>   * Note that host-state that does change is set elsewhere. E.g., host-state
> @@ -7756,6 +7812,8 @@ static struct kvm_x86_ops vmx_x86_ops = {
>  	.load_eoi_exitmap = vmx_load_eoi_exitmap,
>  	.hwapic_irr_update = vmx_hwapic_irr_update,
>  	.hwapic_isr_update = vmx_hwapic_isr_update,
> +	.sync_pir_to_irr = vmx_sync_pir_to_irr,
> +	.deliver_posted_interrupt = vmx_deliver_posted_interrupt,
>  
>  	.set_tss_addr = vmx_set_tss_addr,
>  	.get_tdp_level = get_ept_level,
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 2d44013..8ad1799 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1671,6 +1671,7 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
>  			smp_send_reschedule(cpu);
>  	put_cpu();
>  }
> +EXPORT_SYMBOL_GPL(kvm_vcpu_kick);
>  #endif /* !CONFIG_S390 */
>  
>  void kvm_resched(struct kvm_vcpu *vcpu)
> -- 
> 1.7.1

--
			Gleb.