linux-kernel - Re: [PATCH v11 13/22] vfio: Introduce common function to add capabilities

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Message-ID: <62fbdd2a-6e5b-6a2f-6312-6c2f35bb577c@nvidia.com>
Date:   Wed, 9 Nov 2016 02:16:17 +0530
From:   Kirti Wankhede <kwankhede@...dia.com>
To:     Alexey Kardashevskiy <aik@...abs.ru>, <alex.williamson@...hat.com>,
        <pbonzini@...hat.com>, <kraxel@...hat.com>, <cjia@...dia.com>
CC:     <qemu-devel@...gnu.org>, <kvm@...r.kernel.org>,
        <kevin.tian@...el.com>, <jike.song@...el.com>,
        <bjsdjshi@...ux.vnet.ibm.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v11 13/22] vfio: Introduce common function to add
 capabilities



On 11/8/2016 12:59 PM, Alexey Kardashevskiy wrote:
> On 05/11/16 08:10, Kirti Wankhede wrote:
>> Vendor driver using mediated device framework should use
>> vfio_info_add_capability() to add capabilities.
>> Introduced this function to reduce code duplication in vendor drivers.
>>
>> Signed-off-by: Kirti Wankhede <kwankhede@...dia.com>
>> Signed-off-by: Neo Jia <cjia@...dia.com>
>> Change-Id: I6fca329fa2291f37a2c859d0bc97574d9e2ce1a6
>> ---
>>  drivers/vfio/vfio.c  | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>>  include/linux/vfio.h |  3 +++
>>  2 files changed, 62 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
>> index 4ed1a6a247c6..9a03be0942a1 100644
>> --- a/drivers/vfio/vfio.c
>> +++ b/drivers/vfio/vfio.c
>> @@ -1797,8 +1797,66 @@ void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset)
>>  	for (tmp = caps->buf; tmp->next; tmp = (void *)tmp + tmp->next - offset)
>>  		tmp->next += offset;
>>  }
>> -EXPORT_SYMBOL_GPL(vfio_info_cap_shift);
>> +EXPORT_SYMBOL(vfio_info_cap_shift);
> 
> 
> Why this change?
> 
> 

We want this symbol to be available to all drivers.


>>  
>> +static int sparse_mmap_cap(struct vfio_info_cap *caps, void *cap_type)
>> +{
>> +	struct vfio_info_cap_header *header;
>> +	struct vfio_region_info_cap_sparse_mmap *sparse_cap, *sparse = cap_type;
>> +	size_t size;
>> +
>> +	size = sizeof(*sparse) + sparse->nr_areas *  sizeof(*sparse->areas);
>> +	header = vfio_info_cap_add(caps, size,
>> +				   VFIO_REGION_INFO_CAP_SPARSE_MMAP, 1);
>> +	if (IS_ERR(header))
>> +		return PTR_ERR(header);
>> +
>> +	sparse_cap = container_of(header,
>> +			struct vfio_region_info_cap_sparse_mmap, header);
>> +	sparse_cap->nr_areas = sparse->nr_areas;
>> +	memcpy(sparse_cap->areas, sparse->areas,
>> +	       sparse->nr_areas * sizeof(*sparse->areas));
>> +	return 0;
>> +}
>> +
>> +static int region_type_cap(struct vfio_info_cap *caps, void *cap_type)
>> +{
>> +	struct vfio_info_cap_header *header;
>> +	struct vfio_region_info_cap_type *type_cap, *cap = cap_type;
>> +
>> +	header = vfio_info_cap_add(caps, sizeof(*cap),
>> +				   VFIO_REGION_INFO_CAP_TYPE, 1);
>> +	if (IS_ERR(header))
>> +		return PTR_ERR(header);
>> +
>> +	type_cap = container_of(header, struct vfio_region_info_cap_type,
>> +				header);
>> +	type_cap->type = cap->type;
>> +	type_cap->subtype = cap->subtype;
>> +	return 0;
>> +}
>> +
>> +int vfio_info_add_capability(struct vfio_info_cap *caps, int cap_type_id,
>> +			     void *cap_type)
>> +{
>> +	int ret = -EINVAL;
>> +
>> +	if (!cap_type)
>> +		return 0;
>> +
>> +	switch (cap_type_id) {
>> +	case VFIO_REGION_INFO_CAP_SPARSE_MMAP:
>> +		ret = sparse_mmap_cap(caps, cap_type);
>> +		break;
>> +
>> +	case VFIO_REGION_INFO_CAP_TYPE:
>> +		ret = region_type_cap(caps, cap_type);
>> +		break;
>> +	}
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL(vfio_info_add_capability);
>>  
>>  /*
>>   * Pin a set of guest PFNs and return their associated host PFNs for local
>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
>> index dcda8fccefab..cf90393a11e2 100644
>> --- a/include/linux/vfio.h
>> +++ b/include/linux/vfio.h
>> @@ -113,6 +113,9 @@ extern struct vfio_info_cap_header *vfio_info_cap_add(
>>  		struct vfio_info_cap *caps, size_t size, u16 id, u16 version);
>>  extern void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset);
>>  
>> +extern int vfio_info_add_capability(struct vfio_info_cap *caps,
>> +				    int cap_type_id, void *cap_type);
>> +
> 
> 
> It would make it easier to review and bisect if 14/22 was squashed into
> this one. 

This was split based on Alex's suggestion on earlier version of this
patchset.

> In the resulting patch, vfio_info_cap_add() can be made static as
> it will only be used in drivers/vfio/vfio.c from now.
> 

Not sure that vfio_info_cap_add() should be made static. If there are
any other drivers using this symbol outside kernel might break with that
change.

Thanks,
Kirti

> 
> 
> 
>>  struct pci_dev;
>>  #ifdef CONFIG_EEH
>>  extern void vfio_spapr_pci_eeh_open(struct pci_dev *pdev);
>>
> 
>