Re: [PATCH v2 42/54] KVM: arm/arm64: vgic-new: vgic_kvm_device: access to VGIC registers

[Marc Zyngier <marc.zyngier@arm.com>]

On 03/05/16 11:09, Andre Przywara wrote:
> Hi,
> 
> On 03/05/16 10:59, Marc Zyngier wrote:
>> On 28/04/16 17:46, Andre Przywara wrote:
>>> From: Eric Auger <eric.auger@linaro.org>
>>>
>>> This patch implements the switches for KVM_DEV_ARM_VGIC_GRP_DIST_REGS
>>> and KVM_DEV_ARM_VGIC_GRP_CPU_REGS API which allows the userspace to
>>> access VGIC registers.
>>>
>>> At that stage the interfaces with the MMIO API are not implemented:
>>> - vgic_attr_regs_access
>>> - vgic_v2_has_attr_regs
>>>
>>> Signed-off-by: Eric Auger <eric.auger@linaro.org>
>>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>>> ---
>>>  virt/kvm/arm/vgic/vgic-kvm-device.c | 53 +++++++++++++++++++++++++++++++++++--
>>>  virt/kvm/arm/vgic/vgic-mmio-v2.c    | 34 ++++++++++++++++++++++++
>>>  virt/kvm/arm/vgic/vgic.h            |  1 +
>>>  3 files changed, 86 insertions(+), 2 deletions(-)
>>>
>>
>> [...]
>>
>>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>> index ae6077e..f2a8efe 100644
>>> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>> @@ -276,3 +276,37 @@ int vgic_v2_dist_uaccess(struct kvm_vcpu *vcpu, bool is_write,
>>>  
>>>  	return ret;
>>>  }
>>> +
>>> +int vgic_v2_has_attr_regs(struct kvm_device *dev, struct kvm_device_attr *attr)
>>> +{
>>> +	int nr_irqs = dev->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
>>> +	const struct vgic_register_region *regions;
>>> +	gpa_t addr;
>>> +	int nr_regions, i, len;
>>> +
>>> +	addr = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
>>> +
>>> +	switch (attr->group) {
>>> +	case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
>>> +		regions = vgic_v2_dist_registers;
>>> +		nr_regions = ARRAY_SIZE(vgic_v2_dist_registers);
>>> +		break;
>>> +	case KVM_DEV_ARM_VGIC_GRP_CPU_REGS:
>>> +		return -ENXIO;		/* TODO: describe CPU i/f regs also */
>>
>> This definitely needs addressing, as it breaks guest migration.
> 
> It is implemented in patch 46/54.
> Shall I remove the TODO to avoid confusion and/or replace it with a note
> either in a comment or in this commit message that the implementation
> will follow in one the next patches?

I just checked, and I stand by my initial comment. Patch 46 does
implement the accessors, but nothing actually wires them here.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...