[PATCH v3 7/9] arm/arm64: KVM: vgic: delay vgic allocation until init time

[Christoffer Dall]

On Tue, Jul 08, 2014 at 12:09:06PM +0100, Marc Zyngier wrote:
> It is now quite easy to delay the allocation of the vgic tables
> until we actually require it to be up and running (when the first

the first starting ?

> starting to kick around).
> 
> This allow us to allocate memory for the exact number of CPUs we
> have. As nobody configures the number of interrupts just yet,
> use a fallback to VGIC_NR_IRQS_LEGACY.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
> ---
>  arch/arm/kvm/arm.c     |  7 -------
>  include/kvm/arm_vgic.h |  1 -
>  virt/kvm/arm/vgic.c    | 42 +++++++++++++++++++++++++++++-------------
>  3 files changed, 29 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index 782632e..9b3957d 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -308,16 +308,9 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
>  
>  int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
>  {
> -	int ret;
> -
>  	/* Force users to call KVM_ARM_VCPU_INIT */
>  	vcpu->arch.target = -1;
>  
> -	/* Set up VGIC */
> -	ret = kvm_vgic_vcpu_init(vcpu);
> -	if (ret)
> -		return ret;
> -
>  	/* Set up the timer */
>  	kvm_timer_vcpu_init(vcpu);
>  
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index 9feb7fe..311a0f0 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -233,7 +233,6 @@ int kvm_vgic_hyp_init(void);
>  int kvm_vgic_init(struct kvm *kvm);
>  int kvm_vgic_create(struct kvm *kvm);
>  void kvm_vgic_destroy(struct kvm *kvm);
> -int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu);
>  void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu);
>  void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu);
>  void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu);
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 47a14a1..708aed9 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -1612,15 +1612,12 @@ static int vgic_vcpu_init_maps(struct kvm_vcpu *vcpu, int nr_irqs)
>   * Initialize the vgic_cpu struct and vgic_dist struct fields pertaining to
>   * this vcpu and enable the VGIC for this VCPU
>   */
> -int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
> +static void kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
>  {
>  	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
>  	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
>  	int i;
>  
> -	if (vcpu->vcpu_id >= dist->nr_cpus)
> -		return -EBUSY;
> -
>  	for (i = 0; i < dist->nr_irqs; i++) {
>  		if (i < VGIC_NR_PPIS)
>  			vgic_bitmap_set_irq_val(&dist->irq_enabled,
> @@ -1640,8 +1637,6 @@ int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
>  	vgic_cpu->nr_lr = vgic->nr_lr;
>  
>  	vgic_enable(vcpu);
> -
> -	return 0;
>  }
>  
>  static void vgic_init_maintenance_interrupt(void *info)
> @@ -1759,8 +1754,17 @@ static int vgic_init_maps(struct kvm *kvm)
>  	int nr_cpus, nr_irqs;
>  	int ret, i;
>  
> -	nr_cpus = dist->nr_cpus = KVM_MAX_VCPUS;
> +	if (dist->nr_cpus)	/* Already allocated */
> +		return 0;
> +
> +	nr_cpus = dist->nr_cpus = atomic_read(&kvm->online_vcpus);
> +	if (!nr_cpus)		/* No vcpus? Can't be good... */
> +		return -EINVAL;
>  
> +	/*
> +	 * If nobody configured the number of interrupts, use the
> +	 * legacy one.
> +	 */
>  	if (!dist->nr_irqs)
>  		dist->nr_irqs = VGIC_NR_IRQS_LEGACY;
>  
> @@ -1804,6 +1808,9 @@ static int vgic_init_maps(struct kvm *kvm)
>  		}
>  	}
>  
> +	for (i = VGIC_NR_PRIVATE_IRQS; i < dist->nr_irqs; i += 4)
> +		vgic_set_target_reg(kvm, 0, i);
> +
>  out:
>  	if (ret)
>  		kvm_vgic_destroy(kvm);
> @@ -1822,6 +1829,7 @@ out:
>   */
>  int kvm_vgic_init(struct kvm *kvm)
>  {
> +	struct kvm_vcpu *vcpu;
>  	int ret = 0, i;
>  
>  	if (!irqchip_in_kernel(kvm))
> @@ -1839,6 +1847,12 @@ int kvm_vgic_init(struct kvm *kvm)
>  		goto out;
>  	}
>  
> +	ret = vgic_init_maps(kvm);
> +	if (ret) {
> +		kvm_err("Unable to allocate maps\n");
> +		goto out;
> +	}
> +
>  	ret = kvm_phys_addr_ioremap(kvm, kvm->arch.vgic.vgic_cpu_base,
>  				    vgic->vcpu_base, KVM_VGIC_V2_CPU_SIZE);
>  	if (ret) {
> @@ -1846,11 +1860,13 @@ int kvm_vgic_init(struct kvm *kvm)
>  		goto out;
>  	}
>  
> -	for (i = VGIC_NR_PRIVATE_IRQS; i < kvm->arch.vgic.nr_irqs; i += 4)
> -		vgic_set_target_reg(kvm, 0, i);
> +	kvm_for_each_vcpu(i, vcpu, kvm)
> +		kvm_vgic_vcpu_init(vcpu);
>  
>  	kvm->arch.vgic.ready = true;
>  out:
> +	if (ret)
> +		kvm_vgic_destroy(kvm);
>  	mutex_unlock(&kvm->lock);
>  	return ret;
>  }
> @@ -1891,10 +1907,6 @@ int kvm_vgic_create(struct kvm *kvm)
>  	kvm->arch.vgic.vgic_dist_base = VGIC_ADDR_UNDEF;
>  	kvm->arch.vgic.vgic_cpu_base = VGIC_ADDR_UNDEF;
>  
> -	ret = vgic_init_maps(kvm);
> -	if (ret)
> -		kvm_err("Unable to allocate maps\n");
> -
>  out_unlock:
>  	for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) {
>  		vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx);
> @@ -2095,6 +2107,10 @@ static int vgic_attr_regs_access(struct kvm_device *dev,
>  
>  	mutex_lock(&dev->kvm->lock);
>  
> +	ret = vgic_init_maps(dev->kvm);
> +	if (ret)
> +		goto out;
> +
>  	if (cpuid >= atomic_read(&dev->kvm->online_vcpus)) {
>  		ret = -EINVAL;
>  		goto out;
> -- 
> 2.0.0
> 
Reviewed-by: Christoffer Dall <christoffer.dall at linaro.org>