linux-kernel - Re: [PATCH v3 5/7] vfio: move barmap to a separate function and export

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Message-ID: <20251121093949.54f647a6.alex@shazbot.org>
Date: Fri, 21 Nov 2025 09:39:49 -0700
From: Alex Williamson <alex@...zbot.org>
To: <ankita@...dia.com>
Cc: <jgg@...pe.ca>, <yishaih@...dia.com>, <skolothumtho@...dia.com>,
 <kevin.tian@...el.com>, <aniketa@...dia.com>, <vsethi@...dia.com>,
 <mochs@...dia.com>, <Yunxiang.Li@....com>, <yi.l.liu@...el.com>,
 <zhangdongdong@...incomputing.com>, <avihaih@...dia.com>,
 <bhelgaas@...gle.com>, <peterx@...hat.com>, <pstanner@...hat.com>,
 <apopple@...dia.com>, <kvm@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>, <cjia@...dia.com>, <kwankhede@...dia.com>,
 <targupta@...dia.com>, <zhiw@...dia.com>, <danw@...dia.com>,
 <dnigam@...dia.com>, <kjaju@...dia.com>
Subject: Re: [PATCH v3 5/7] vfio: move barmap to a separate function and
 export

On Fri, 21 Nov 2025 14:11:39 +0000
<ankita@...dia.com> wrote:

> From: Ankit Agrawal <ankita@...dia.com>
> 
> Move the code to map the BAR to a separate function.
> 
> This would be reused by the nvgrace-gpu module.
> 
> Signed-off-by: Ankit Agrawal <ankita@...dia.com>
> ---
>  drivers/vfio/pci/vfio_pci_core.c | 38 ++++++++++++++++++++++----------
>  include/linux/vfio_pci_core.h    |  1 +
>  2 files changed, 27 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
> index 29dcf78905a6..d1ff1c0aa727 100644
> --- a/drivers/vfio/pci/vfio_pci_core.c
> +++ b/drivers/vfio/pci/vfio_pci_core.c
> @@ -1717,6 +1717,29 @@ static const struct vm_operations_struct vfio_pci_mmap_ops = {
>  #endif
>  };
>  
> +int vfio_pci_core_barmap(struct vfio_pci_core_device *vdev, unsigned int index)
> +{
> +	struct pci_dev *pdev = vdev->pdev;
> +	int ret;
> +
> +	if (vdev->barmap[index])
> +		return 0;
> +
> +	ret = pci_request_selected_regions(pdev,
> +					   1 << index, "vfio-pci");
> +	if (ret)
> +		return ret;
> +
> +	vdev->barmap[index] = pci_iomap(pdev, index, 0);
> +	if (!vdev->barmap[index]) {
> +		pci_release_selected_regions(pdev, 1 << index);
> +		return -ENOMEM;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(vfio_pci_core_barmap);

Looks a lot like vfio_pci_core_setup_barmap() ;)

Thanks,
Alex


> +
>  int vfio_pci_core_mmap(struct vfio_device *core_vdev, struct vm_area_struct *vma)
>  {
>  	struct vfio_pci_core_device *vdev =
> @@ -1761,18 +1784,9 @@ int vfio_pci_core_mmap(struct vfio_device *core_vdev, struct vm_area_struct *vma
>  	 * Even though we don't make use of the barmap for the mmap,
>  	 * we need to request the region and the barmap tracks that.
>  	 */
> -	if (!vdev->barmap[index]) {
> -		ret = pci_request_selected_regions(pdev,
> -						   1 << index, "vfio-pci");
> -		if (ret)
> -			return ret;
> -
> -		vdev->barmap[index] = pci_iomap(pdev, index, 0);
> -		if (!vdev->barmap[index]) {
> -			pci_release_selected_regions(pdev, 1 << index);
> -			return -ENOMEM;
> -		}
> -	}
> +	ret = vfio_pci_core_barmap(vdev, index);
> +	if (ret)
> +		return ret;
>  
>  	vma->vm_private_data = vdev;
>  	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
> index a097a66485b4..75f04d613e0c 100644
> --- a/include/linux/vfio_pci_core.h
> +++ b/include/linux/vfio_pci_core.h
> @@ -121,6 +121,7 @@ ssize_t vfio_pci_core_write(struct vfio_device *core_vdev, const char __user *bu
>  		size_t count, loff_t *ppos);
>  vm_fault_t vfio_pci_map_pfn(struct vm_fault *vmf, unsigned long pfn,
>  			    unsigned int order);
> +int vfio_pci_core_barmap(struct vfio_pci_core_device *vdev, unsigned int index);
>  int vfio_pci_core_mmap(struct vfio_device *core_vdev, struct vm_area_struct *vma);
>  void vfio_pci_core_request(struct vfio_device *core_vdev, unsigned int count);
>  int vfio_pci_core_match(struct vfio_device *core_vdev, char *buf);