Add TPH metadata fields to struct vfio_pci_dma_buf to store PH,
basic/extended ST and their validity flags.

Implement vfio_pci_dma_buf_get_pci_tph() to fetch TPH tag and PH from
dmabuf, distinguish basic and extended ST namespace.

Add vfio_pci_dma_buf_get_tph_by_fd() to resolve TPH data via dmabuf fd,
validate dmabuf owner ops. Provide stub implementation if
CONFIG_VFIO_PCI_DMABUF is unset.

Lay dmabuf foundation for the upcoming TPH_RESOLVE feature.

Signed-off-by: Zhiping Zhang <zhipingz@meta.com>
Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
---
 drivers/vfio/pci/vfio_pci_dmabuf.c | 49 +++++++++++++++++++++++++++++-
 drivers/vfio/pci/vfio_pci_priv.h   |  6 ++++
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c
index c16f460c01d6..d9c5e434e586 100644
--- a/drivers/vfio/pci/vfio_pci_dmabuf.c
+++ b/drivers/vfio/pci/vfio_pci_dmabuf.c
@@ -19,7 +19,14 @@ struct vfio_pci_dma_buf {
 	u32 nr_ranges;
 	struct kref kref;
 	struct completion comp;
-	u8 revoked : 1;
+
+	/* Protected by dmabuf->resv. */
+	u8 revoked:1;
+	u8 tph_ph:2;
+	u8 tph_st_valid:1;
+	u8 tph_xst_valid:1;
+	u8 tph_st;
+	u16 tph_xst;
 };
 
 static int vfio_pci_dma_buf_attach(struct dma_buf *dmabuf,
@@ -81,6 +88,26 @@ static void vfio_pci_dma_buf_unmap(struct dma_buf_attachment *attachment,
 	kref_put(&priv->kref, vfio_pci_dma_buf_done);
 }
 
+static int vfio_pci_dma_buf_get_pci_tph(struct dma_buf *dmabuf, bool extended,
+					u16 *tag, u8 *ph)
+{
+	struct vfio_pci_dma_buf *priv = dmabuf->priv;
+
+	dma_resv_assert_held(priv->dmabuf->resv);
+
+	if (extended) {
+		if (!priv->tph_xst_valid)
+			return -EOPNOTSUPP;
+		*tag = priv->tph_xst;
+	} else {
+		if (!priv->tph_st_valid)
+			return -EOPNOTSUPP;
+		*tag = priv->tph_st;
+	}
+	*ph = priv->tph_ph;
+	return 0;
+}
+
 static void vfio_pci_dma_buf_release(struct dma_buf *dmabuf)
 {
 	struct vfio_pci_dma_buf *priv = dmabuf->priv;
@@ -106,6 +133,26 @@ static const struct dma_buf_ops vfio_pci_dmabuf_ops = {
 	.release = vfio_pci_dma_buf_release,
 };
 
+int vfio_pci_dma_buf_get_tph_by_fd(int fd, bool extended, u16 *tag, u8 *ph)
+{
+	struct dma_buf *dmabuf;
+	int ret = 0;
+
+	dmabuf = dma_buf_get(fd);
+	if (IS_ERR(dmabuf))
+		return PTR_ERR(dmabuf);
+
+	if (dmabuf->ops != &vfio_pci_dmabuf_ops) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = vfio_pci_dma_buf_get_pci_tph(dmabuf, extended, tag, ph);
+out:
+	dma_buf_put(dmabuf);
+	return ret;
+}
+
 /*
  * This is a temporary "private interconnect" between VFIO DMABUF and iommufd.
  * It allows the two co-operating drivers to exchange the physical address of
diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_priv.h
index c997cc9bf330..d7bc52f488c6 100644
--- a/drivers/vfio/pci/vfio_pci_priv.h
+++ b/drivers/vfio/pci/vfio_pci_priv.h
@@ -122,12 +122,18 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev)
 }
 
 #ifdef CONFIG_VFIO_PCI_DMABUF
+int vfio_pci_dma_buf_get_tph_by_fd(int fd, bool extended, u16 *tag, u8 *ph);
 int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags,
 				  struct vfio_device_feature_dma_buf __user *arg,
 				  size_t argsz);
 void vfio_pci_dma_buf_cleanup(struct vfio_pci_core_device *vdev);
 void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revoked);
 #else
+static inline int vfio_pci_dma_buf_get_tph_by_fd(int fd, bool extended,
+						 u16 *tag, u8 *ph)
+{
+	return -EOPNOTSUPP;
+}
 static inline int
 vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags,
 			      struct vfio_device_feature_dma_buf __user *arg,
-- 
2.17.1