Re: [PATCH 3/9] Remove irq_pending bitmap

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On Tuesday 05 May 2009 16:14:29 Gleb Natapov wrote:
> Only one interrupt vector can be injected from userspace irqchip at
> any given time so no need to store it in a bitmap. Put it into interrupt
> queue directly.
>
> Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
> ---
>  arch/x86/include/asm/kvm_host.h |    2 --
>  arch/x86/kvm/irq.c              |    4 ++--
>  arch/x86/kvm/x86.c              |   38
> +++++++++++--------------------------- arch/x86/kvm/x86.h              |  
> 12 ------------
>  4 files changed, 13 insertions(+), 43 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h
> b/arch/x86/include/asm/kvm_host.h index 8e680c3..cc892f5 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -266,8 +266,6 @@ struct kvm_mmu {
>
>  struct kvm_vcpu_arch {
>  	u64 host_tsc;
> -	unsigned long irq_summary; /* bit vector: 1 per word in irq_pending */
> -	DECLARE_BITMAP(irq_pending, KVM_NR_INTERRUPTS);
>  	/*
>  	 * rip and regs accesses must go through
>  	 * kvm_{register,rip}_{read,write} functions.
> diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c
> index 11c2757..96dfbb6 100644
> --- a/arch/x86/kvm/irq.c
> +++ b/arch/x86/kvm/irq.c
> @@ -50,7 +50,7 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *v)
>  	struct kvm_pic *s;
>
>  	if (!irqchip_in_kernel(v->kvm))
> -		return v->arch.irq_summary;
> +		return v->arch.interrupt.pending;
>
>  	if (kvm_apic_has_interrupt(v) == -1) {	/* LAPIC */
>  		if (kvm_apic_accept_pic_intr(v)) {
> @@ -72,7 +72,7 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v)
>  	int vector;
>
>  	if (!irqchip_in_kernel(v->kvm))
> -		return kvm_pop_irq(v);
> +		return v->arch.interrupt.nr;
>
>  	vector = kvm_get_apic_interrupt(v);	/* APIC */
>  	if (vector == -1) {
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 12ab1cc..4596927 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1424,8 +1424,7 @@ static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu
> *vcpu, return -ENXIO;
>  	vcpu_load(vcpu);
>
> -	set_bit(irq->irq, vcpu->arch.irq_pending);
> -	set_bit(irq->irq / BITS_PER_LONG, &vcpu->arch.irq_summary);
> +	kvm_queue_interrupt(vcpu, irq->irq);
>
>  	vcpu_put(vcpu);
>
> @@ -3562,12 +3561,7 @@ int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu
> *vcpu, sregs->efer = vcpu->arch.shadow_efer;
>  	sregs->apic_base = kvm_get_apic_base(vcpu);
>
> -	if (irqchip_in_kernel(vcpu->kvm))
> -		memset(sregs->interrupt_bitmap, 0,
> -		       sizeof sregs->interrupt_bitmap);

? When did we discard the saving of pending interrupt for irqchip_in_kernel?

> -	else
> -		memcpy(sregs->interrupt_bitmap, vcpu->arch.irq_pending,
> -		       sizeof sregs->interrupt_bitmap);
> +	memset(sregs->interrupt_bitmap, 0, sizeof sregs->interrupt_bitmap);

No need to save any pending interrupts? Did I miss anything?

>  	if (vcpu->arch.interrupt.pending)
>  		set_bit(vcpu->arch.interrupt.nr,
> @@ -4037,7 +4031,7 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu
> *vcpu, struct kvm_sregs *sregs)
>  {
>  	int mmu_reset_needed = 0;
> -	int i, pending_vec, max_bits;
> +	int pending_vec, max_bits;
>  	struct descriptor_table dt;
>
>  	vcpu_load(vcpu);
> @@ -4079,24 +4073,14 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu
> *vcpu, if (mmu_reset_needed)
>  		kvm_mmu_reset_context(vcpu);
>
> -	if (!irqchip_in_kernel(vcpu->kvm)) {
> -		memcpy(vcpu->arch.irq_pending, sregs->interrupt_bitmap,
> -		       sizeof vcpu->arch.irq_pending);
> -		vcpu->arch.irq_summary = 0;
> -		for (i = 0; i < ARRAY_SIZE(vcpu->arch.irq_pending); ++i)
> -			if (vcpu->arch.irq_pending[i])
> -				__set_bit(i, &vcpu->arch.irq_summary);
> -	} else {
> -		max_bits = (sizeof sregs->interrupt_bitmap) << 3;
> -		pending_vec = find_first_bit(
> -			(const unsigned long *)sregs->interrupt_bitmap,
> -			max_bits);
> -		/* Only pending external irq is handled here */
> -		if (pending_vec < max_bits) {
> -			kvm_queue_interrupt(vcpu, pending_vec);
> -			pr_debug("Set back pending irq %d\n", pending_vec);
> -		}
> -		kvm_pic_clear_isr_ack(vcpu->kvm);
> +	max_bits = (sizeof sregs->interrupt_bitmap) << 3;

If interrupt_bitmap is always zero as above, why we got this... For 
compatible?

-- 
regards
Yang, Sheng

> +	pending_vec = find_first_bit(
> +		(const unsigned long *)sregs->interrupt_bitmap, max_bits);
> +	if (pending_vec < max_bits) {
> +		kvm_queue_interrupt(vcpu, pending_vec);
> +		pr_debug("Set back pending irq %d\n", pending_vec);
> +		if (irqchip_in_kernel(vcpu->kvm))
> +			kvm_pic_clear_isr_ack(vcpu->kvm);
>  	}
>
>  	kvm_set_segment(vcpu, &sregs->cs, VCPU_SREG_CS);
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index 21203d4..c1f1a8c 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -19,18 +19,6 @@ static inline void kvm_clear_interrupt_queue(struct
> kvm_vcpu *vcpu) vcpu->arch.interrupt.pending = false;
>  }
>
> -static inline u8 kvm_pop_irq(struct kvm_vcpu *vcpu)
> -{
> -	int word_index = __ffs(vcpu->arch.irq_summary);
> -	int bit_index = __ffs(vcpu->arch.irq_pending[word_index]);
> -	int irq = word_index * BITS_PER_LONG + bit_index;
> -
> -	clear_bit(bit_index, &vcpu->arch.irq_pending[word_index]);
> -	if (!vcpu->arch.irq_pending[word_index])
> -		clear_bit(word_index, &vcpu->arch.irq_summary);
> -	return irq;
> -}
> -
>  static inline bool kvm_event_needs_reinjection(struct kvm_vcpu *vcpu)
>  {
>  	return vcpu->arch.exception.pending || vcpu->arch.interrupt.pending ||


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