linux-kernel - Re: [PATCH v2 5/6] vfio: selftests: Add helper to set/override a vf

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Message-ID: <aV7kq76DYIx8aNVv@google.com>
Date: Wed, 7 Jan 2026 22:56:43 +0000
From: David Matlack <dmatlack@...gle.com>
To: Raghavendra Rao Ananta <rananta@...gle.com>
Cc: Alex Williamson <alex@...zbot.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	Josh Hilke <jrhilke@...gle.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/6] vfio: selftests: Add helper to set/override a
 vf_token

On 2025-12-10 06:14 PM, Raghavendra Rao Ananta wrote:
> Add a helper function, vfio_device_set_vf_token(), to set or override a
> vf_token. Not only at init, but a vf_token can also be set via the
> VFIO_DEVICE_FEATURE ioctl, by setting the
> VFIO_DEVICE_FEATURE_PCI_VF_TOKEN flag. Hence, add an API to utilize this
> functionality from the test code. The subsequent commit will use this to
> test the functionality of this method to set the vf_token.
> 
> Signed-off-by: Raghavendra Rao Ananta <rananta@...gle.com>
> ---
>  .../lib/include/libvfio/vfio_pci_device.h     |  2 ++
>  .../selftests/vfio/lib/vfio_pci_device.c      | 34 +++++++++++++++++++
>  2 files changed, 36 insertions(+)
> 
> diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
> index 6186ca463ca6e..b370aa6a74d0b 100644
> --- a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
> +++ b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
> @@ -129,4 +129,6 @@ void vfio_container_set_iommu(struct vfio_pci_device *device);
>  void vfio_pci_iommufd_cdev_open(struct vfio_pci_device *device, const char *bdf);
>  int __vfio_device_bind_iommufd(int device_fd, int iommufd, const char *vf_token);
>  
> +void vfio_device_set_vf_token(int fd, const char *vf_token);
> +
>  #endif /* SELFTESTS_VFIO_LIB_INCLUDE_LIBVFIO_VFIO_PCI_DEVICE_H */
> diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> index 208da2704d9e2..7725ecc62b024 100644
> --- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> +++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> @@ -109,6 +109,40 @@ static void vfio_pci_irq_get(struct vfio_pci_device *device, u32 index,
>  	ioctl_assert(device->fd, VFIO_DEVICE_GET_IRQ_INFO, irq_info);
>  }
>  
> +static int vfio_device_feature_ioctl(int fd, u32 flags, void *data,
> +				     size_t data_size)
> +{
> +	u8 buffer[sizeof(struct vfio_device_feature) + data_size] = {};
> +	struct vfio_device_feature *feature = (void *)buffer;
> +
> +	memcpy(feature->data, data, data_size);
> +
> +	feature->argsz = sizeof(buffer);
> +	feature->flags = flags;
> +
> +	return ioctl(fd, VFIO_DEVICE_FEATURE, feature);
> +}
> +
> +static void vfio_device_feature_set(int fd, u16 feature, void *data, size_t data_size)
> +{
> +	u32 flags = VFIO_DEVICE_FEATURE_SET | feature;
> +	int ret;
> +
> +	ret = vfio_device_feature_ioctl(fd, flags, data, data_size);
> +	VFIO_ASSERT_EQ(ret, 0, "Failed to set feature %u\n", feature);
> +}
> +
> +void vfio_device_set_vf_token(int fd, const char *vf_token)
> +{
> +	uuid_t token_uuid = {0};
> +
> +	VFIO_ASSERT_NOT_NULL(vf_token, "vf_token is NULL");
> +	VFIO_ASSERT_EQ(uuid_parse(vf_token, token_uuid), 0);
> +
> +	vfio_device_feature_set(fd, VFIO_DEVICE_FEATURE_PCI_VF_TOKEN,
> +				token_uuid, sizeof(uuid_t));
> +}

Would it be useful to have a variant that returns an int for negative
testing?

> +
>  static void vfio_pci_region_get(struct vfio_pci_device *device, int index,
>  				struct vfio_region_info *info)
>  {
> -- 
> 2.52.0.239.gd5f0c6e74e-goog
>