[PATCH] KVM: arm64: ITS: move ITS registration into first VCPU run

Auger Eric eric.auger at redhat.com
Thu Aug 4 03:26:57 PDT 2016


Hi Andre,

On 04/08/2016 12:17, Andre Przywara wrote:
> Hi Eric,
> 
> On 04/08/16 11:11, Auger Eric wrote:
>> Hi Andre,
>>
>> On 03/08/2016 16:57, Andre Przywara wrote:
>>> Currently we register ITS devices upon userland issuing the CTRL_INIT
>>> ioctl to mark initialization of the ITS as done.
>>> This deviates from the initialization sequence of the existing GIC
>>> devices and does not play well with the way QEMU handles things.
>>> To be more in line with what we are used to, register the ITS(es) just
>>> before the first VCPU is about to run, so in the map_resources() call.
>>> This involves iterating through the list of KVM devices and handle each
>>> ITS that we find.
>>>
>>> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
>>> ---
>>> Hi,
>>>
>>> this is based upon next-20160728 plus Christoffer's kvm_device locking
>>> fix from today. Please let me know what tree I should base upon and I
>>> will rebase.
>>> Eric, Christoffer: does that do what you expect? Can QEMU live with that?
>>>
>>> Cheers,
>>> Andre.
>>>
>>>  virt/kvm/arm/vgic/vgic-its.c | 56 ++++++++++++++++++++++++++++++++++++--------
>>>  virt/kvm/arm/vgic/vgic-v3.c  |  6 +++++
>>>  virt/kvm/arm/vgic/vgic.h     |  6 +++++
>>>  3 files changed, 58 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>>> index 07411cf..e677a60 100644
>>> --- a/virt/kvm/arm/vgic/vgic-its.c
>>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>>> @@ -1288,13 +1288,13 @@ void vgic_enable_lpis(struct kvm_vcpu *vcpu)
>>>  		its_sync_lpi_pending_table(vcpu);
>>>  }
>>>  
>>> -static int vgic_its_init_its(struct kvm *kvm, struct vgic_its *its)
>>> +static int vgic_register_its_iodev(struct kvm *kvm, struct vgic_its *its)
>>>  {
>>>  	struct vgic_io_device *iodev = &its->iodev;
>>>  	int ret;
>>>  
>>> -	if (its->initialized)
>>> -		return 0;
>>> +	if (!its->initialized)
>>> +		return -EBUSY;
>>>  
>>>  	if (IS_VGIC_ADDR_UNDEF(its->vgic_its_base))
>>>  		return -ENXIO;
>>> @@ -1311,9 +1311,6 @@ static int vgic_its_init_its(struct kvm *kvm, struct vgic_its *its)
>>>  				      KVM_VGIC_V3_ITS_SIZE, &iodev->dev);
>>>  	mutex_unlock(&kvm->slots_lock);
>>>  
>>> -	if (!ret)
>>> -		its->initialized = true;
>>> -
>>>  	return ret;
>>>  }
>>>  
>>> @@ -1435,9 +1432,6 @@ static int vgic_its_set_attr(struct kvm_device *dev,
>>>  		if (type != KVM_VGIC_ITS_ADDR_TYPE)
>>>  			return -ENODEV;
>>>  
>>> -		if (its->initialized)
>>> -			return -EBUSY;
>>> -
>>>  		if (copy_from_user(&addr, uaddr, sizeof(addr)))
>>>  			return -EFAULT;
>>>  
>>> @@ -1453,7 +1447,9 @@ static int vgic_its_set_attr(struct kvm_device *dev,
>>>  	case KVM_DEV_ARM_VGIC_GRP_CTRL:
>>>  		switch (attr->attr) {
>>>  		case KVM_DEV_ARM_VGIC_CTRL_INIT:
>>> -			return vgic_its_init_its(dev->kvm, its);
>>> +			its->initialized = true;
>>> +
>>> +			return 0;
>>>  		}
>>>  		break;
>>>  	}
>>> @@ -1498,3 +1494,43 @@ int kvm_vgic_register_its_device(void)
>>>  	return kvm_register_device_ops(&kvm_arm_vgic_its_ops,
>>>  				       KVM_DEV_TYPE_ARM_VGIC_ITS);
>>>  }
>>> +
>>> +/*
>>> + * Registers all ITSes with the kvm_io_bus framework.
>>> + * To follow the existing VGIC initialization sequence, this has to be
>>> + * done as late as possible, just before the first VCPU runs.
>>> + */
>>> +int vgic_register_its_iodevs(struct kvm *kvm)
>>> +{
>>> +	struct kvm_device *dev;
>>> +	int ret = 0;
>>> +
>>> +	mutex_lock(&kvm->devices_lock);
>>> +
>>> +	list_for_each_entry(dev, &kvm->devices, vm_node) {
>>> +		if (dev->ops != &kvm_arm_vgic_its_ops)
>>> +			continue;
>>> +
>>> +		ret = vgic_register_its_iodev(kvm, dev->private);
>>> +		if (ret)
>>> +			break;
>>> +	}
>>> +
>>> +	if (ret) {
>>> +		/* Iterate backwards to roll back previous registrations. */
>>> +		for (dev = list_prev_entry(dev, vm_node);
>>> +		     &dev->vm_node != &kvm->devices;
>>> +		     dev = list_prev_entry(dev, vm_node)) {
>>> +			struct vgic_its *its = dev->private;
>>> +
>>> +			if (dev->ops != &kvm_arm_vgic_its_ops)
>>> +				continue;
>>> +
>>> +			kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS,
>>> +						  &its->iodev.dev);
>>> +		}
>>> +	}
>>> +
>>> +	mutex_unlock(&kvm->devices_lock);
>>> +	return ret;
>>> +}
>>> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
>>> index 0506543..f0d9b2b 100644
>>> --- a/virt/kvm/arm/vgic/vgic-v3.c
>>> +++ b/virt/kvm/arm/vgic/vgic-v3.c
>>> @@ -289,6 +289,12 @@ int vgic_v3_map_resources(struct kvm *kvm)
>>>  		goto out;
>>>  	}
>>>  
>> don't you need to check vgic_has_its() first
> 
> I guess it's nice to do so, though technically it's not necessary, since
> we won't find any KVM devices which use the ITS ops if no ITS has been
> created.
> But since I respin this one anyway...
agreed. that's not critical.

Cheers

Eric
> 
> Cheers,
> Andre.
> 
>> Eric
>>> +	ret = vgic_register_its_iodevs(kvm);
>>> +	if (ret) {
>>> +		kvm_err("Unable to register VGIC ITS MMIO regions\n");
>>> +		goto out;
>>> +	}
>>> +
>>>  	dist->ready = true;
>>>  
>>>  out:
>>> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
>>> index 1d8e21d..6c4625c 100644
>>> --- a/virt/kvm/arm/vgic/vgic.h
>>> +++ b/virt/kvm/arm/vgic/vgic.h
>>> @@ -84,6 +84,7 @@ void vgic_v3_enable(struct kvm_vcpu *vcpu);
>>>  int vgic_v3_probe(const struct gic_kvm_info *info);
>>>  int vgic_v3_map_resources(struct kvm *kvm);
>>>  int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t dist_base_address);
>>> +int vgic_register_its_iodevs(struct kvm *kvm);
>>>  bool vgic_has_its(struct kvm *kvm);
>>>  int kvm_vgic_register_its_device(void);
>>>  void vgic_enable_lpis(struct kvm_vcpu *vcpu);
>>> @@ -140,6 +141,11 @@ static inline int vgic_register_redist_iodevs(struct kvm *kvm,
>>>  	return -ENODEV;
>>>  }
>>>  
>>> +static inline int vgic_register_its_iodevs(struct kvm *kvm)
>>> +{
>>> +	return -ENODEV;
>>> +}
>>> +
>>>  static inline bool vgic_has_its(struct kvm *kvm)
>>>  {
>>>  	return false;
>>>
>>
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