Re: [PATCH v11 3/5] PCI/TPH: Add pcie_tph_enabled_mode() helper

[Alex Williamson <alex@shazbot.org>]

On Mon, 18 May 2026 15:16:59 +0800
Chengwen Feng <fengchengwen@huawei.com> wrote:

> Add a helper to query enabled TPH mode on a PCI device. This is useful for
> drivers like VFIO-PCI that need to validate TPH state before allowing
> access to steering tag tables.
> 
> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
> ---
>  drivers/pci/tph.c       | 12 ++++++++++++
>  include/linux/pci-tph.h |  3 +++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c
> index ba31b010f67a..91c1e83410a3 100644
> --- a/drivers/pci/tph.c
> +++ b/drivers/pci/tph.c
> @@ -451,6 +451,18 @@ int pcie_enable_tph(struct pci_dev *pdev, int mode)
>  }
>  EXPORT_SYMBOL(pcie_enable_tph);
>  
> +/**
> + * pcie_tph_enabled_mode - Get current enabled TPH mode
> + * @pdev: PCI device
> + *
> + * Return the enabled TPH mode (IV/DS) or 0 if disabled.
> + */
> +int pcie_tph_enabled_mode(struct pci_dev *pdev)
> +{
> +	return pdev->tph_enabled ? pdev->tph_mode : 0;
> +}
> +EXPORT_SYMBOL(pcie_tph_enabled_mode);

Doesn't this create ambiguity with PCI_TPH_ST_NS_MODE?  Maybe return an
-errno if not enabled.  Duplicate same for stub below.  Thanks,

Alex

> +
>  void pci_restore_tph_state(struct pci_dev *pdev)
>  {
>  	struct pci_cap_saved_state *save_state;
> diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h
> index 5772d48ea444..28d0fa762146 100644
> --- a/include/linux/pci-tph.h
> +++ b/include/linux/pci-tph.h
> @@ -28,6 +28,7 @@ int pcie_tph_get_cpu_st(struct pci_dev *dev,
>  			unsigned int cpu, u16 *tag);
>  void pcie_disable_tph(struct pci_dev *pdev);
>  int pcie_enable_tph(struct pci_dev *pdev, int mode);
> +int pcie_tph_enabled_mode(struct pci_dev *pdev);
>  u16 pcie_tph_get_st_table_size(struct pci_dev *pdev);
>  u32 pcie_tph_get_st_table_loc(struct pci_dev *pdev);
>  u8 pcie_tph_get_st_modes(struct pci_dev *pdev);
> @@ -42,6 +43,8 @@ static inline int pcie_tph_get_cpu_st(struct pci_dev *dev,
>  static inline void pcie_disable_tph(struct pci_dev *pdev) { }
>  static inline int pcie_enable_tph(struct pci_dev *pdev, int mode)
>  { return -EINVAL; }
> +static inline int pcie_tph_enabled_mode(struct pci_dev *pdev)
> +{ return 0; }
>  static inline u16 pcie_tph_get_st_table_size(struct pci_dev *pdev)
>  { return 0; }
>  static inline u32 pcie_tph_get_st_table_loc(struct pci_dev *pdev)