linux-kernel - Re: [PATCH 09/10] vfio/pci: Share the core device pointer while invoking feature functions

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Message-ID: <20250728145553.53e94d49.alex.williamson@redhat.com>
Date: Mon, 28 Jul 2025 14:55:53 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: Leon Romanovsky <leon@...nel.org>
Cc: Vivek Kasireddy <vivek.kasireddy@...el.com>, Christoph Hellwig
 <hch@....de>, Jason Gunthorpe <jgg@...dia.com>, Andrew Morton
 <akpm@...ux-foundation.org>, Bjorn Helgaas <bhelgaas@...gle.com>, Christian
 König <christian.koenig@....com>,
 dri-devel@...ts.freedesktop.org, iommu@...ts.linux.dev, Jens Axboe
 <axboe@...nel.dk>, Jérôme Glisse <jglisse@...hat.com>,
 Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
 linaro-mm-sig@...ts.linaro.org, linux-block@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
 linux-mm@...ck.org, linux-pci@...r.kernel.org, Logan Gunthorpe
 <logang@...tatee.com>, Marek Szyprowski <m.szyprowski@...sung.com>, Robin
 Murphy <robin.murphy@....com>, Sumit Semwal <sumit.semwal@...aro.org>, Will
 Deacon <will@...nel.org>
Subject: Re: [PATCH 09/10] vfio/pci: Share the core device pointer while
 invoking feature functions

On Wed, 23 Jul 2025 16:00:10 +0300
Leon Romanovsky <leon@...nel.org> wrote:

> From: Vivek Kasireddy <vivek.kasireddy@...el.com>
> 
> There is no need to share the main device pointer (struct vfio_device *)
> with all the feature functions as they only need the core device
> pointer. Therefore, extract the core device pointer once in the
> caller (vfio_pci_core_ioctl_feature) and share it instead.
> 
> Signed-off-by: Vivek Kasireddy <vivek.kasireddy@...el.com>
> Signed-off-by: Leon Romanovsky <leonro@...dia.com>
> ---
>  drivers/vfio/pci/vfio_pci_core.c | 30 +++++++++++++-----------------
>  1 file changed, 13 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
> index 1e675daab5753..5512d13bb8899 100644
> --- a/drivers/vfio/pci/vfio_pci_core.c
> +++ b/drivers/vfio/pci/vfio_pci_core.c
> @@ -301,11 +301,9 @@ static int vfio_pci_runtime_pm_entry(struct vfio_pci_core_device *vdev,
>  	return 0;
>  }
>  
> -static int vfio_pci_core_pm_entry(struct vfio_device *device, u32 flags,
> +static int vfio_pci_core_pm_entry(struct vfio_pci_core_device *vdev, u32 flags,
>  				  void __user *arg, size_t argsz)
>  {
> -	struct vfio_pci_core_device *vdev =
> -		container_of(device, struct vfio_pci_core_device, vdev);
>  	int ret;
>  
>  	ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_SET, 0);
> @@ -322,12 +320,10 @@ static int vfio_pci_core_pm_entry(struct vfio_device *device, u32 flags,
>  }
>  
>  static int vfio_pci_core_pm_entry_with_wakeup(
> -	struct vfio_device *device, u32 flags,
> +	struct vfio_pci_core_device *vdev, u32 flags,
>  	struct vfio_device_low_power_entry_with_wakeup __user *arg,
>  	size_t argsz)

I'm tempted to fix the line wrapping here, but I think this patch
stands on its own.  Even if it's rather trivial, it makes sense to
consolidate and standardize on the vfio_pci_core_device getting passed
around within vfio_pci_core.c.  Any reason not to split this off?
Thanks,

Alex

>  {
> -	struct vfio_pci_core_device *vdev =
> -		container_of(device, struct vfio_pci_core_device, vdev);
>  	struct vfio_device_low_power_entry_with_wakeup entry;
>  	struct eventfd_ctx *efdctx;
>  	int ret;
> @@ -378,11 +374,9 @@ static void vfio_pci_runtime_pm_exit(struct vfio_pci_core_device *vdev)
>  	up_write(&vdev->memory_lock);
>  }
>  
> -static int vfio_pci_core_pm_exit(struct vfio_device *device, u32 flags,
> +static int vfio_pci_core_pm_exit(struct vfio_pci_core_device *vdev, u32 flags,
>  				 void __user *arg, size_t argsz)
>  {
> -	struct vfio_pci_core_device *vdev =
> -		container_of(device, struct vfio_pci_core_device, vdev);
>  	int ret;
>  
>  	ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_SET, 0);
> @@ -1475,11 +1469,10 @@ long vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
>  }
>  EXPORT_SYMBOL_GPL(vfio_pci_core_ioctl);
>  
> -static int vfio_pci_core_feature_token(struct vfio_device *device, u32 flags,
> -				       uuid_t __user *arg, size_t argsz)
> +static int vfio_pci_core_feature_token(struct vfio_pci_core_device *vdev,
> +				       u32 flags, uuid_t __user *arg,
> +				       size_t argsz)
>  {
> -	struct vfio_pci_core_device *vdev =
> -		container_of(device, struct vfio_pci_core_device, vdev);
>  	uuid_t uuid;
>  	int ret;
>  
> @@ -1506,16 +1499,19 @@ static int vfio_pci_core_feature_token(struct vfio_device *device, u32 flags,
>  int vfio_pci_core_ioctl_feature(struct vfio_device *device, u32 flags,
>  				void __user *arg, size_t argsz)
>  {
> +	struct vfio_pci_core_device *vdev =
> +		container_of(device, struct vfio_pci_core_device, vdev);
> +
>  	switch (flags & VFIO_DEVICE_FEATURE_MASK) {
>  	case VFIO_DEVICE_FEATURE_LOW_POWER_ENTRY:
> -		return vfio_pci_core_pm_entry(device, flags, arg, argsz);
> +		return vfio_pci_core_pm_entry(vdev, flags, arg, argsz);
>  	case VFIO_DEVICE_FEATURE_LOW_POWER_ENTRY_WITH_WAKEUP:
> -		return vfio_pci_core_pm_entry_with_wakeup(device, flags,
> +		return vfio_pci_core_pm_entry_with_wakeup(vdev, flags,
>  							  arg, argsz);
>  	case VFIO_DEVICE_FEATURE_LOW_POWER_EXIT:
> -		return vfio_pci_core_pm_exit(device, flags, arg, argsz);
> +		return vfio_pci_core_pm_exit(vdev, flags, arg, argsz);
>  	case VFIO_DEVICE_FEATURE_PCI_VF_TOKEN:
> -		return vfio_pci_core_feature_token(device, flags, arg, argsz);
> +		return vfio_pci_core_feature_token(vdev, flags, arg, argsz);
>  	default:
>  		return -ENOTTY;
>  	}