Re: [PATCH v2 2/3] vfio/pci: Replace vfio_pci_core_setup_barmap() with checks for resource/map

[Matt Evans <mattev@meta.com>]

Hi Leon,

On 26/04/2026 12:05, Leon Romanovsky wrote:
> > 
> On Thu, Apr 23, 2026 at 11:25:08AM -0700, Matt Evans wrote:
>> Since "vfio/pci: Set up barmap in vfio_pci_core_enable()", the
>> resource request and iomap for the BARs was performed early, and
>> vfio_pci_core_setup_barmap() now just checks those actions succeeded.
>>
>> There were two types of callers:
>>   - Those that need the iomap, because they'll access the BAR
>>   - Those that need the resource, because they'll map/export it
>>
>> This replaces vfio_pci_core_setup_barmap() with two helpers,
>> vfio_pci_core_check_barmap_valid() and vfio_pci_core_check_bar_rsrc(),
>> to make it clear which behaviour is required in each caller.
>>
>> Signed-off-by: Matt Evans <mattev@meta.com>
>> ---
>>   drivers/vfio/pci/nvgrace-gpu/main.c |  8 +++-----
>>   drivers/vfio/pci/vfio_pci_core.c    |  5 ++---
>>   drivers/vfio/pci/vfio_pci_rdwr.c    | 22 ++--------------------
>>   drivers/vfio/pci/virtio/legacy_io.c |  4 ++--
>>   include/linux/vfio_pci_core.h       | 23 ++++++++++++++++++++++-
>>   5 files changed, 31 insertions(+), 31 deletions(-)
> 
> <...>
> 
>> +/* Returns 0 if vdev->barmap[bar] can be accessed, otherwise errno */
>> +static inline int
>> +vfio_pci_core_check_barmap_valid(struct vfio_pci_core_device *vdev, int bar)
>> +{
>> +	if (bar < 0 || bar >= PCI_STD_NUM_BARS)
>> +		return -EINVAL;
>> +	if (vdev->barmap[bar] == 0)
> 
> I understand this line was copied from an earlier implementation, but
> barmap[bar] is a pointer, and it is set to NULL when it is released.
> 
>   if (!dev->barmap[bar])
>     return -ENOMEM;

Absolutely.  Fixed in upcoming v3, thank you,


Matt

> 
> Thanks
> 
>> +		return -ENOMEM;
>> +	return 0;
>> +}
>> +
>> +/* Returns 0 if BAR has a valid resource reserved for use, otherwise errno */
>> +static inline int vfio_pci_core_check_bar_rsrc(struct vfio_pci_core_device *vdev,
>> +					       int bar)
>> +{
>> +	if (bar < 0 || bar >= PCI_STD_NUM_BARS)
>> +		return -EINVAL;
>> +	if (!vdev->have_bar_resource[bar])
>> +		return -EBUSY;
>> +	return 0;
>> +}
>> +
>>   static inline bool is_aligned_for_order(struct vm_area_struct *vma,
>>   					unsigned long addr,
>>   					unsigned long pfn,
>> -- 
>> 2.47.3
>>