[SLOF] [PATCH v1 08/27] virtio: make virtio_get_qsize 1.0 aware

[Nikunj A Dadhania]

Alexey Kardashevskiy <aik at ozlabs.ru> writes:

> On 01/14/2016 09:57 PM, Nikunj A Dadhania wrote:
>> Alexey Kardashevskiy <aik at ozlabs.ru> writes:
>>
>>> On 01/13/2016 10:16 PM, Nikunj A Dadhania wrote:
>>>> Also return unsigned int
>>>
>>> Why?
>>
>> Size is not negative :-)
>
>
> The size equal to 0xffffffff makes as much sense as a negative one ;)
> Are sizes in other places all unsigned already? If yes, then add this note 
> to the commit log, if not, then change it in other places in a separate patch.
>
>
> btw (out of curiosity) while looking at the kernel tree about 
> VIRTIOHDR_QUEUE_SIZE, I could not spot its counterpart there, I thought it 
> is VIRTIO_PCI_COMMON_Q_SIZE but it is not, what is it?


So virtio 1.0 now has various structures and not just offsets (legacy).
It added following capability structures common, device, isr, notify and
pci. Various different registers were the spread across this structures.


>
>
>>
>>>
>>>
>>>>
>>>> Signed-off-by: Nikunj A Dadhania <nikunj at linux.vnet.ibm.com>
>>>> ---
>>>>    lib/libvirtio/virtio.c | 15 +++++++++++----
>>>>    lib/libvirtio/virtio.h |  2 +-
>>>>    2 files changed, 12 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/lib/libvirtio/virtio.c b/lib/libvirtio/virtio.c
>>>> index bcf050b..77676c7 100644
>>>> --- a/lib/libvirtio/virtio.c
>>>> +++ b/lib/libvirtio/virtio.c
>>>> @@ -185,17 +185,24 @@ unsigned long virtio_vring_size(unsigned int qsize)
>>>>     * @param   queue virtio queue number
>>>>     * @return  number of elements
>>>>     */
>>>> -int virtio_get_qsize(struct virtio_device *dev, int queue)
>>>> +unsigned int virtio_get_qsize(struct virtio_device *dev, int queue)
>>>>    {
>>>> -	int size = 0;
>>>> +	unsigned int size = 0;
>>>>
>>>> -	if (dev->type == VIRTIO_TYPE_PCI) {
>>>> +	if (dev->type != VIRTIO_TYPE_PCI)
>>>> +		return 0;
>>>> +	if (dev->is_modern) {
>>>> +		void *addr = dev->common.addr + offset_of(struct virtio_dev_common, q_select);
>>>> +		ci_write_16(addr, cpu_to_le16(queue));
>>>> +		eieio();
>>>> +		size = le16_to_cpu(ci_read_16(addr + 2));
>>>
>>>
>>> Please add commit log explaining this magic.
>>
>> Sure.
>>
>>>
>>>
>>>> +	}
>>>> +	else {
>>>>    		ci_write_16(dev->base+VIRTIOHDR_QUEUE_SELECT,
>>>>    			    cpu_to_le16(queue));
>>>>    		eieio();
>>>>    		size = le16_to_cpu(ci_read_16(dev->base+VIRTIOHDR_QUEUE_SIZE));
>>>>    	}
>>>> -
>>>
>>> Unrelated change.
>>
>> Yep.
>>
>>>
>>>
>>>>    	return size;
>>>>    }
>>>>
>>>> diff --git a/lib/libvirtio/virtio.h b/lib/libvirtio/virtio.h
>>>> index eee3144..537862b 100644
>>>> --- a/lib/libvirtio/virtio.h
>>>> +++ b/lib/libvirtio/virtio.h
>>>> @@ -107,7 +107,7 @@ struct vqs {
>>>>    #define VQ_ALIGN(addr)	(((addr) + 0xfff) & ~0xfff)
>>>>
>>>>    extern unsigned long virtio_vring_size(unsigned int qsize);
>>>> -extern int virtio_get_qsize(struct virtio_device *dev, int queue);
>>>> +extern unsigned int virtio_get_qsize(struct virtio_device *dev, int queue);
>>>>    extern struct vring_desc *virtio_get_vring_desc(struct virtio_device *dev, int queue);
>>>>    extern struct vring_avail *virtio_get_vring_avail(struct virtio_device *dev, int queue);
>>>>    extern struct vring_used *virtio_get_vring_used(struct virtio_device *dev, int queue);
>>>>
>>>
>>>
>>> --
>>> Alexey
>>
>
>
> -- 
> Alexey