Subject: [PATCH v3 05/19] arm/arm64: KVM: introduce per-VM ops

From: [email-masked] (Andre Przywara)
Date: Tue, 04 Nov 2014 15:58:27 +0000

Hi Christoffer,

as hinted on IRC, an earlier reply on this one got lost on my machine,
so please excuse my apparent ignorance on your previous comments.

On 03/11/14 13:59, Christoffer Dall wrote:
> On Fri, Oct 31, 2014 at 05:26:40PM +0000, Andre Przywara wrote:
>> Currently we only have one virtual GIC model supported, so all guests
>> use the same emulation code. With the addition of another model we
>> end up with different guests using potentially different vGIC models,
>> so we have to split up some functions to be per VM.
>> Introduce a vgic_vm_ops struct to hold function pointers for those
>> functions that are different and provide the necessary code to
>> initialize them.
>>
>> Signed-off-by: Andre Przywara <[email-masked]>
>> ---
>>  include/kvm/arm_vgic.h |   10 ++++++
>>  virt/kvm/arm/vgic.c    |   81 +++++++++++++++++++++++++++++++++++-------------
>>  2 files changed, 69 insertions(+), 22 deletions(-)
>>
>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
>> index dde5a00..bfb660a 100644
>> --- a/include/kvm/arm_vgic.h
>> +++ b/include/kvm/arm_vgic.h
>> @@ -134,6 +134,14 @@ struct vgic_params {
>>  	void __iomem	*vctrl_base;
>>  };
>>  
>> +struct vgic_vm_ops {
>> +	bool	(*handle_mmio)(struct kvm_vcpu *, struct kvm_run *,
>> +			       struct kvm_exit_mmio *);
>> +	bool	(*queue_sgi)(struct kvm_vcpu *vcpu, int irq);
>> +	void	(*add_sgi_source)(struct kvm_vcpu *vcpu, int irq, int source);
>> +	int	(*vgic_init)(struct kvm *kvm, const struct vgic_params *params);
>> +};
>> +
>>  struct vgic_dist {
>>  #ifdef CONFIG_KVM_ARM_VGIC
>>  	spinlock_t		lock;
>> @@ -215,6 +223,8 @@ struct vgic_dist {
>>  
>>  	/* Bitmap indicating which CPU has something pending */
>>  	unsigned long		*irq_pending_on_cpu;
>> +
>> +	struct vgic_vm_ops	vm_ops;
>>  #endif
>>  };
>>  
>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>> index 0cbdde9..2c16684 100644
>> --- a/virt/kvm/arm/vgic.c
>> +++ b/virt/kvm/arm/vgic.c
>> @@ -105,6 +105,8 @@ static void vgic_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr);
>>  static const struct vgic_ops *vgic_ops;
>>  static const struct vgic_params *vgic;
>>  
>> +#define vgic_vm_op(kvm, fn) ((kvm)->arch.vgic.vm_ops.fn)
>> +
> 
> another one?  why did you simply ignore my comment from the last review?
> 
> If it wasn't obvious last time around, YUCK, and no ;)

OK, which version would you like?

1) Actually my first solution was to decode it on each call-site directly:

vcpu->kvm->arch.vgic.vm_ops.add_sgi_source(vcpu, lr.irq, lr.source);

However one reviewer suggested to wrap it with the macro you see above.

2) Provide a static inline for each seems like overkill, since there is
only one caller for each of them, but it would look like this:

static void add_sgi_source(struct kvm_vcpu *vcpu, int irq, int source)
{
        vcpu->kvm->arch.vgic.vm_ops.add_sgi_source(vcpu, irq, source);
}

Both don't look very convincing to me, so if you see other
colors^Wsolutions, please let me know ;-)

We have to choose between them at _runtime_, because there could be two
guests with different vGIC models running at the same time.

>>  /*
>>   * struct vgic_bitmap contains a bitmap made of unsigned longs, but
>>   * extracts u32s out of them.
>> @@ -761,6 +763,13 @@ static bool handle_mmio_sgi_reg(struct kvm_vcpu *vcpu,
>>  	return false;
>>  }
>>  
>> +static void vgic_v2_add_sgi_source(struct kvm_vcpu *vcpu, int irq, int source)
>> +{
>> +	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
>> +
>> +	*vgic_get_sgi_sources(dist, vcpu->vcpu_id, irq) |= 1 << source;
>> +}
>> +
>>  /**
>>   * vgic_unqueue_irqs - move pending IRQs from LRs to the distributor
>>   * @vgic_cpu: Pointer to the vgic_cpu struct holding the LRs
>> @@ -775,9 +784,7 @@ static bool handle_mmio_sgi_reg(struct kvm_vcpu *vcpu,
>>   */
>>  static void vgic_unqueue_irqs(struct kvm_vcpu *vcpu)
>>  {
>> -	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
>>  	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
>> -	int vcpu_id = vcpu->vcpu_id;
>>  	int i;
>>  
>>  	for_each_set_bit(i, vgic_cpu->lr_used, vgic_cpu->nr_lr) {
>> @@ -804,7 +811,8 @@ static void vgic_unqueue_irqs(struct kvm_vcpu *vcpu)
>>  		 */
>>  		vgic_dist_irq_set_pending(vcpu, lr.irq);
>>  		if (lr.irq < VGIC_NR_SGIS)
>> -			*vgic_get_sgi_sources(dist, vcpu_id, lr.irq) |= 1 << lr.source;
>> +			vgic_vm_op(vcpu->kvm, add_sgi_source)(vcpu, lr.irq,
>> +							      lr.source);
>>  		lr.state &= ~LR_STATE_PENDING;
>>  		vgic_set_lr(vcpu, i, lr);
>>  
>> @@ -1162,7 +1170,7 @@ bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
>>  	if (!irqchip_in_kernel(vcpu->kvm))
>>  		return false;
>>  
>> -	return vgic_v2_handle_mmio(vcpu, run, mmio);
>> +	return vgic_vm_op(vcpu->kvm, handle_mmio)(vcpu, run, mmio);
>>  }
>>  
>>  static u8 *vgic_get_sgi_sources(struct vgic_dist *dist, int vcpu_id, int sgi)
>> @@ -1414,7 +1422,7 @@ static bool vgic_queue_irq(struct kvm_vcpu *vcpu, u8 sgi_source_id, int irq)
>>  	return true;
>>  }
>>  
>> -static bool vgic_queue_sgi(struct kvm_vcpu *vcpu, int irq)
>> +static bool vgic_v2_queue_sgi(struct kvm_vcpu *vcpu, int irq)
>>  {
>>  	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
>>  	unsigned long sources;
>> @@ -1489,7 +1497,7 @@ static void __kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
>>  
>>  	/* SGIs */
>>  	for_each_set_bit(i, vgic_cpu->pending_percpu, VGIC_NR_SGIS) {
>> -		if (!vgic_queue_sgi(vcpu, i))
>> +		if (!vgic_vm_op(vcpu->kvm, queue_sgi)(vcpu, i))
>>  			overflow = 1;
>>  	}
>>  
>> @@ -1944,9 +1952,6 @@ 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);
>> -
> 
> Remind me, why are we moving this chunk?

The target registers are only valid for vGICv2 (we have other means for
GICv3), so this belongs now into the vGICv2 specific code.

Cheers,
Andre.

>>  out:
>>  	if (ret)
>>  		kvm_vgic_destroy(kvm);
>> @@ -1954,6 +1959,31 @@ out:
>>  	return ret;
>>  }
>>  
>> +static int vgic_v2_init(struct kvm *kvm, const struct vgic_params *params)
>> +{
>> +	struct vgic_dist *dist = &kvm->arch.vgic;
>> +	int ret, i;
>> +
>> +	if (IS_VGIC_ADDR_UNDEF(dist->vgic_dist_base) ||
>> +	    IS_VGIC_ADDR_UNDEF(dist->vgic_cpu_base)) {
>> +		kvm_err("Need to set vgic distributor addresses first\n");
>> +		return -ENXIO;
>> +	}
>> +
>> +	ret = kvm_phys_addr_ioremap(kvm, dist->vgic_cpu_base,
>> +				    params->vcpu_base,
>> +				    KVM_VGIC_V2_CPU_SIZE, true);
>> +	if (ret) {
>> +		kvm_err("Unable to remap VGIC CPU to VCPU\n");
>> +		return ret;
>> +	}
>> +
>> +	for (i = VGIC_NR_PRIVATE_IRQS; i < dist->nr_irqs; i += 4)
>> +		vgic_set_target_reg(kvm, 0, i);
>> +
>> +	return 0;
>> +}
>> +
>>  /**
>>   * kvm_vgic_init - Initialize global VGIC state before running any VCPUs
>>   * @kvm: pointer to the kvm struct
>> @@ -1976,26 +2006,15 @@ int kvm_vgic_init(struct kvm *kvm)
>>  	if (vgic_initialized(kvm))
>>  		goto out;
>>  
>> -	if (IS_VGIC_ADDR_UNDEF(kvm->arch.vgic.vgic_dist_base) ||
>> -	    IS_VGIC_ADDR_UNDEF(kvm->arch.vgic.vgic_cpu_base)) {
>> -		kvm_err("Need to set vgic cpu and dist addresses first\n");
>> -		ret = -ENXIO;
>> -		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,
>> -				    true);
>> -	if (ret) {
>> -		kvm_err("Unable to remap VGIC CPU to VCPU\n");
>> +	ret = vgic_vm_op(kvm, vgic_init)(kvm, vgic);
>> +	if (ret)
>>  		goto out;
>> -	}
>>  
>>  	kvm_for_each_vcpu(i, vcpu, kvm)
>>  		kvm_vgic_vcpu_init(vcpu);
>> @@ -2008,6 +2027,21 @@ out:
>>  	return ret;
>>  }
>>  
>> +static bool init_emulation_ops(struct kvm *kvm, int type)
>> +{
>> +	struct vgic_dist *dist = &kvm->arch.vgic;
>> +
>> +	switch (type) {
>> +	case KVM_DEV_TYPE_ARM_VGIC_V2:
>> +		dist->vm_ops.handle_mmio = vgic_v2_handle_mmio;
>> +		dist->vm_ops.queue_sgi = vgic_v2_queue_sgi;
>> +		dist->vm_ops.add_sgi_source = vgic_v2_add_sgi_source;
>> +		dist->vm_ops.vgic_init = vgic_v2_init;
>> +		return true;
>> +	}
>> +	return false;
>> +}
>> +
>>  int kvm_vgic_create(struct kvm *kvm, u32 type)
>>  {
>>  	int i, vcpu_lock_idx = -1, ret = 0;
>> @@ -2045,6 +2079,9 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
>>  	kvm->arch.vgic.vgic_dist_base = VGIC_ADDR_UNDEF;
>>  	kvm->arch.vgic.vgic_cpu_base = VGIC_ADDR_UNDEF;
>>  
>> +	if (!init_emulation_ops(kvm, type))
>> +		ret = -ENODEV;
>> +
>>  out_unlock:
>>  	for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) {
>>  		vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx);
>> -- 
>> 1.7.9.5
>>
> 
> -Christoffer
>