On Sun, Oct 26, 2025 at 09:44:16PM -0700, Vivek Kasireddy wrote:
> Add support for IOV interconnect by provding ops for map/unmap and
> match interconnect. Note that the xarray is populated with entries
> of type struct range. The range type contains the start and end
> addresses of the memory region.
>
> Cc: Jason Gunthorpe <[email protected]>
> Cc: Christian Koenig <[email protected]>
> Cc: Sumit Semwal <[email protected]>
> Cc: Thomas Hellström <[email protected]>
> Cc: Simona Vetter <[email protected]>
> Signed-off-by: Vivek Kasireddy <[email protected]>
> ---
> drivers/vfio/pci/vfio_pci_dmabuf.c | 135 ++++++++++++++++++++++++++++-
> 1 file changed, 134 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c
> b/drivers/vfio/pci/vfio_pci_dmabuf.c
> index eaba010777f3..d2b7b5410e5a 100644
> --- a/drivers/vfio/pci/vfio_pci_dmabuf.c
> +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c
In drm-tip vfio_pci_dmabuf.c does not exist as a file? Is this series
based on another series / branch where vfio_pci_dmabuf.c hasn't made it
into drm-tip yet?
Matt
> @@ -4,6 +4,7 @@
> #include <linux/dma-buf.h>
> #include <linux/pci-p2pdma.h>
> #include <linux/dma-resv.h>
> +#include <linux/range.h>
>
> #include "vfio_pci_priv.h"
>
> @@ -16,15 +17,132 @@ struct vfio_pci_dma_buf {
> size_t size;
> struct phys_vec *phys_vec;
> struct p2pdma_provider *provider;
> + struct dma_buf_interconnect_match *ic_match;
> u32 nr_ranges;
> u8 revoked : 1;
> };
>
> +static int
> +vfio_pci_create_match(struct vfio_pci_dma_buf *priv,
> + struct vfio_device_feature_dma_buf *dma_buf)
> +{
> + struct dma_buf_interconnect_match *ic_match;
> +
> + ic_match = kzalloc(sizeof(*ic_match), GFP_KERNEL);
> + if (!ic_match)
> + return -ENOMEM;
> +
> + ic_match->dev = &priv->vdev->pdev->dev;
> + ic_match->bar = dma_buf->region_index;
> +
> + priv->ic_match = ic_match;
> + return 0;
> +}
> +
> +static int vfio_pci_map_iov_interconnect(struct vfio_pci_dma_buf *priv,
> + struct xarray *ranges)
> +{
> + struct phys_vec *phys_vec = priv->phys_vec;
> + struct range *range;
> + unsigned long i;
> + void *entry;
> + int ret;
> +
> + range = kmalloc_array(priv->nr_ranges, sizeof(*range), GFP_KERNEL);
> + if (!range)
> + return -ENOMEM;
> +
> + for (i = 0; i < priv->nr_ranges; i++) {
> + entry = &range[i];
> + range[i].start = phys_vec[i].paddr;
> + range[i].end = phys_vec[i].paddr + phys_vec[i].len - 1;
> +
> + entry = xa_store(ranges, i, entry, GFP_KERNEL);
> + if (xa_is_err(entry)) {
> + ret = xa_err(entry);
> + goto err_free_range;
> + }
> + }
> + return 0;
> +
> +err_free_range:
> + kfree(range);
> + return ret;
> +}
> +
> +static int vfio_pci_map_interconnect(struct dma_buf_attachment *attachment,
> + struct dma_buf_ranges *ranges)
> +{
> + const struct dma_buf_interconnect *ic = attachment->ic_match->type;
> + struct vfio_pci_dma_buf *priv = attachment->dmabuf->priv;
> + int ret = -EINVAL;
> +
> + ranges->nranges = priv->nr_ranges;
> +
> + if (ic == iov_interconnect)
> + ret = vfio_pci_map_iov_interconnect(priv, &ranges->ranges);
> +
> + return ret;
> +}
> +
> +static void vfio_pci_unmap_interconnect(struct dma_buf_attachment
> *attachment,
> + struct dma_buf_ranges *ranges)
> +{
> + void *entry;
> +
> + entry = xa_load(&ranges->ranges, 0);
> + kfree(entry);
> +}
> +
> +static bool
> +vfio_pci_match_iov_interconnect(const struct dma_buf_interconnect_match *exp,
> + const struct dma_buf_interconnect_match *imp)
> +{
> + struct pci_dev *exp_pdev = to_pci_dev(exp->dev);
> + struct pci_dev *imp_pdev = to_pci_dev(imp->dev);
> +
> + return imp_pdev == pci_physfn(exp_pdev) && imp->bar == exp->bar;
> +}
> +
> +static bool
> +vfio_pci_match_interconnect(const struct dma_buf_interconnect_match *exp,
> + const struct dma_buf_interconnect_match *imp)
> +{
> + const struct dma_buf_interconnect *ic = exp->type;
> +
> + if (ic == iov_interconnect)
> + return vfio_pci_match_iov_interconnect(exp, imp);
> +
> + return false;
> +}
> +
> +static bool
> +vfio_pci_match_interconnects(struct vfio_pci_dma_buf *priv,
> + struct dma_buf_attachment *attachment)
> +{
> + const struct dma_buf_attach_ops *aops = attachment->importer_ops;
> + const struct dma_buf_interconnect_match supports_ics[] = {
> + MATCH_INTERCONNECT(iov_interconnect,
> + priv->ic_match->dev, priv->ic_match->bar),
> + };
> +
> + if (attachment->allow_ic) {
> + if (aops->supports_interconnects(attachment, supports_ics,
> + ARRAY_SIZE(supports_ics)))
> + return true;
> + }
> + return false;
> +}
> +
> static int vfio_pci_dma_buf_attach(struct dma_buf *dmabuf,
> struct dma_buf_attachment *attachment)
> {
> struct vfio_pci_dma_buf *priv = dmabuf->priv;
>
> + if (vfio_pci_match_interconnects(priv, attachment)) {
> + return 0;
> + }
> +
> if (!attachment->peer2peer)
> return -EOPNOTSUPP;
>
> @@ -189,6 +307,7 @@ vfio_pci_dma_buf_map(struct dma_buf_attachment
> *attachment,
> return ERR_PTR(ret);
> }
>
> +
> static void vfio_pci_dma_buf_unmap(struct dma_buf_attachment *attachment,
> struct sg_table *sgt,
> enum dma_data_direction dir)
> @@ -228,15 +347,23 @@ static void vfio_pci_dma_buf_release(struct dma_buf
> *dmabuf)
> vfio_device_put_registration(&priv->vdev->vdev);
> }
> kfree(priv->phys_vec);
> + kfree(priv->ic_match);
> kfree(priv);
> }
>
> +static const struct dma_buf_interconnect_ops vfio_pci_interconnect_ops = {
> + .match_interconnect = vfio_pci_match_interconnect,
> + .map_interconnect = vfio_pci_map_interconnect,
> + .unmap_interconnect = vfio_pci_unmap_interconnect,
> +};
> +
> static const struct dma_buf_ops vfio_pci_dmabuf_ops = {
> .attach = vfio_pci_dma_buf_attach,
> .detach = vfio_pci_dma_buf_detach,
> .map_dma_buf = vfio_pci_dma_buf_map,
> .release = vfio_pci_dma_buf_release,
> .unmap_dma_buf = vfio_pci_dma_buf_unmap,
> + .interconnect_ops = &vfio_pci_interconnect_ops,
> };
>
> static void dma_ranges_to_p2p_phys(struct vfio_pci_dma_buf *priv,
> @@ -365,6 +492,10 @@ int vfio_pci_core_feature_dma_buf(struct
> vfio_pci_core_device *vdev, u32 flags,
> goto err_free_phys;
> }
>
> + ret = vfio_pci_create_match(priv, &get_dma_buf);
> + if (ret)
> + goto err_dev_put;
> +
> exp_info.ops = &vfio_pci_dmabuf_ops;
> exp_info.size = priv->size;
> exp_info.flags = get_dma_buf.open_flags;
> @@ -373,7 +504,7 @@ int vfio_pci_core_feature_dma_buf(struct
> vfio_pci_core_device *vdev, u32 flags,
> priv->dmabuf = dma_buf_export(&exp_info);
> if (IS_ERR(priv->dmabuf)) {
> ret = PTR_ERR(priv->dmabuf);
> - goto err_dev_put;
> + goto err_free_iov;
> }
>
> /* dma_buf_put() now frees priv */
> @@ -391,6 +522,8 @@ int vfio_pci_core_feature_dma_buf(struct
> vfio_pci_core_device *vdev, u32 flags,
> */
> return dma_buf_fd(priv->dmabuf, get_dma_buf.open_flags);
>
> +err_free_iov:
> + kfree(priv->ic_match);
> err_dev_put:
> vfio_device_put_registration(&vdev->vdev);
> err_free_phys:
> --
> 2.50.1
>
