On Wed, Feb 01, 2023 at 05:20:18PM +0200, Alvaro Karsz wrote:
> Add a print explaining why vhost_vdpa_alloc_domain failed if the device
> is not IOMMU cache coherent capable.
>
> Without this print, we have no hint why the operation failed.
>
> For example:
>
> $ virsh start <domain>
> error: Failed to start domain <domain>
> error: Unable to open '/dev/vhost-vdpa-<idx>' for vdpa device:
> Unknown error 524
>
> Suggested-by: Eugenio Perez Martin <eperezma@xxxxxxxxxx>
> Signed-off-by: Alvaro Karsz <alvaro.karsz@xxxxxxxxxxxxx>
I'm not sure this is a good idea. Userspace is not supposed to be
able to trigger dev_err.
> ---
> drivers/vhost/vdpa.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 23db92388393..56287506aa0d 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -1151,8 +1151,11 @@ static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v)
> if (!bus)
> return -EFAULT;
>
> - if (!device_iommu_capable(dma_dev, IOMMU_CAP_CACHE_COHERENCY))
> + if (!device_iommu_capable(dma_dev, IOMMU_CAP_CACHE_COHERENCY)) {
> + dev_err(&v->dev,
> + "Failed to allocate domain, device is not IOMMU cache coherent capable\n");
> return -ENOTSUPP;
> + }
>
> v->domain = iommu_domain_alloc(bus);
> if (!v->domain)
> --
> 2.34.1
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