Re: [RFC v3 06/21] vfio: VFIO_IOMMU_BIND_MSI

Alex Williamson
2019-01-11T23:02:52Z

On Tue, 8 Jan 2019 11:26:18 +0100
Eric Auger <eric.auger@redhat.com> wrote:

> This patch adds the VFIO_IOMMU_BIND_MSI ioctl which aims at
> passing the guest MSI binding to the host.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>
> ---
>
> v2 -> v3:
> - adapt to new proto of bind_guest_msi
> - directly use vfio_iommu_for_each_dev
>
> v1 -> v2:
> - s/vfio_iommu_type1_guest_msi_binding/vfio_iommu_type1_bind_guest_msi
> ---
> drivers/vfio/vfio_iommu_type1.c | 27 +++++++++++++++++++++++++++
> include/uapi/linux/vfio.h | 7 +++++++
> 2 files changed, 34 insertions(+)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index c3ba3f249438..59229f6e2d84 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -1673,6 +1673,15 @@ static int vfio_cache_inv_fn(struct device *dev, void *data)
> return iommu_cache_invalidate(d, dev, &ustruct->info);
> }
>
> +static int vfio_bind_guest_msi_fn(struct device *dev, void *data)
> +{
> + struct vfio_iommu_type1_bind_guest_msi *ustruct =
> + (struct vfio_iommu_type1_bind_guest_msi *)data;
> + struct iommu_domain *d = iommu_get_domain_for_dev(dev);
> +
> + return iommu_bind_guest_msi(d, dev, &ustruct->binding);
> +}
> +
> static int
> vfio_set_pasid_table(struct vfio_iommu *iommu,
> struct vfio_iommu_type1_set_pasid_table *ustruct)
> @@ -1792,6 +1801,24 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
> vfio_cache_inv_fn);
> mutex_unlock(&iommu->lock);
> return ret;
> + } else if (cmd == VFIO_IOMMU_BIND_MSI) {
> + struct vfio_iommu_type1_bind_guest_msi ustruct;
> + int ret;
> +
> + minsz = offsetofend(struct vfio_iommu_type1_bind_guest_msi,
> + binding);
> +
> + if (copy_from_user(&ustruct, (void __user *)arg, minsz))
> + return -EFAULT;
> +
> + if (ustruct.argsz < minsz || ustruct.flags)
> + return -EINVAL;
> +
> + mutex_lock(&iommu->lock);
> + ret = vfio_iommu_for_each_dev(iommu, &ustruct,
> + vfio_bind_guest_msi_fn);

The vfio_iommu_for_each_dev() interface is fine for invalidation, where
a partial failure requires no unwind, but it's not sufficiently robust
here.

> + mutex_unlock(&iommu->lock);
> + return ret;
> }
>
> return -ENOTTY;
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 11a07165e7e1..352e795a93c8 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -774,6 +774,13 @@ struct vfio_iommu_type1_cache_invalidate {
> };
> #define VFIO_IOMMU_CACHE_INVALIDATE _IO(VFIO_TYPE, VFIO_BASE + 23)
>
> +struct vfio_iommu_type1_bind_guest_msi {
> + __u32 argsz;
> + __u32 flags;
> + struct iommu_guest_msi_binding binding;
> +};
> +#define VFIO_IOMMU_BIND_MSI _IO(VFIO_TYPE, VFIO_BASE + 24)

-ENOCOMMENTS MSIs are setup and torn down, is this only a machine init
sort of interface? How does the user un-bind? Thanks,

Alex

> +
> /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
>
> /*