Re: [PATCH v5 3/7] PCI/ATS: Initialize PASID in pci_ats_init()

From: Bjorn Helgaas
Date: Mon Aug 12 2019 - 16:04:48 EST

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On Thu, Aug 01, 2019 at 05:06:00PM -0700, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
>
> Currently, PASID Capability checks are repeated across all PASID API's.
> Instead, cache the capability check result in pci_pasid_init() and use
> it in other PASID API's. Also, since PASID is a shared resource between
> PF/VF, initialize PASID features with default values in pci_pasid_init().

Split into two patches as for PRI.

> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> ---
> drivers/pci/ats.c | 74 +++++++++++++++++++++++++++++------------
> include/linux/pci-ats.h | 5 +++
> include/linux/pci.h | 1 +
> 3 files changed, 59 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
> index 280be911f190..1f4be27a071d 100644
> --- a/drivers/pci/ats.c
> +++ b/drivers/pci/ats.c
> @@ -30,6 +30,8 @@ void pci_ats_init(struct pci_dev *dev)
> dev->ats_cap = pos;
>
> pci_pri_init(dev);
> +

Superfluous blank line; you can remove it.

> + pci_pasid_init(dev);
> }
>
> /**
> @@ -315,6 +317,40 @@ EXPORT_SYMBOL_GPL(pci_reset_pri);
> #endif /* CONFIG_PCI_PRI */
>
> #ifdef CONFIG_PCI_PASID
> +
> +void pci_pasid_init(struct pci_dev *pdev)
> +{
> + u16 supported;
> + int pos;
> +
> + /*
> + * As per PCIe r4.0, sec 9.3.7.14, only PF is permitted to
> + * implement PASID Capability and all associated VFs can
> + * only use it. Since PF already initialized the PASID
> + * parameters there is no need to proceed further.
> + */
> + if (pdev->is_virtfn)
> + return;
> +
> + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
> + if (!pos)
> + return;
> +
> + pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
> +
> + supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;
> +
> + /*
> + * Enable all supported features. Since PASID is a shared
> + * resource between PF/VF, we must not set this feature as
> + * a per device property in pci_enable_pasid().

But pci_enable_pasid() *does* set PCI_PASID_CTRL. Either the comments
or the code needs to be updated.

> + */
> + pci_write_config_word(pdev, pos + PCI_PASID_CTRL, supported);
> +
> + pdev->pasid_features = supported;
> + pdev->pasid_cap = pos;
> +}
> +
> /**
> * pci_enable_pasid - Enable the PASID capability
> * @pdev: PCI device structure
> @@ -323,11 +359,13 @@ EXPORT_SYMBOL_GPL(pci_reset_pri);
> * Returns 0 on success, negative value on error. This function checks
> * whether the features are actually supported by the device and returns
> * an error if not.
> + *
> + * TODO: Since PASID is a shared resource between PF/VF, don't update
> + * PASID features in the same API as a per device feature.
> */
> int pci_enable_pasid(struct pci_dev *pdev, int features)
> {
> u16 control, supported;
> - int pos;
>
> if (WARN_ON(pdev->pasid_enabled))
> return -EBUSY;
> @@ -335,11 +373,11 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
> if (!pdev->eetlp_prefix_path)
> return -EINVAL;
>
> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
> - if (!pos)
> + if (!pdev->pasid_cap)
> return -EINVAL;
>
> - pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
> + pci_read_config_word(pdev, pdev->pasid_cap + PCI_PASID_CAP,
> + &supported);
> supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;
>
> /* User wants to enable anything unsupported? */
> @@ -349,7 +387,7 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
> control = PCI_PASID_CTRL_ENABLE | features;
> pdev->pasid_features = features;
>
> - pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
> + pci_write_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL, control);
>
> pdev->pasid_enabled = 1;
>
> @@ -364,16 +402,14 @@ EXPORT_SYMBOL_GPL(pci_enable_pasid);
> void pci_disable_pasid(struct pci_dev *pdev)
> {
> u16 control = 0;
> - int pos;
>
> if (WARN_ON(!pdev->pasid_enabled))
> return;
>
> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
> - if (!pos)
> + if (!pdev->pasid_cap)
> return;
>
> - pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
> + pci_write_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL, control);
>
> pdev->pasid_enabled = 0;
> }
> @@ -386,17 +422,15 @@ EXPORT_SYMBOL_GPL(pci_disable_pasid);
> void pci_restore_pasid_state(struct pci_dev *pdev)
> {
> u16 control;
> - int pos;
>
> if (!pdev->pasid_enabled)
> return;
>
> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
> - if (!pos)
> + if (!pdev->pasid_cap)
> return;
>
> control = PCI_PASID_CTRL_ENABLE | pdev->pasid_features;
> - pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
> + pci_write_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL, control);
> }
> EXPORT_SYMBOL_GPL(pci_restore_pasid_state);
>
> @@ -413,13 +447,12 @@ EXPORT_SYMBOL_GPL(pci_restore_pasid_state);
> int pci_pasid_features(struct pci_dev *pdev)
> {
> u16 supported;
> - int pos;
>
> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
> - if (!pos)
> + if (!pdev->pasid_cap)
> return -EINVAL;
>
> - pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
> + pci_read_config_word(pdev, pdev->pasid_cap + PCI_PASID_CAP,
> + &supported);
>
> supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;
>
> @@ -469,13 +502,12 @@ EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required);
> int pci_max_pasids(struct pci_dev *pdev)
> {
> u16 supported;
> - int pos;
>
> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
> - if (!pos)
> + if (!pdev->pasid_cap)
> return -EINVAL;
>
> - pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
> + pci_read_config_word(pdev, pdev->pasid_cap + PCI_PASID_CAP,
> + &supported);
>
> supported = (supported & PASID_NUMBER_MASK) >> PASID_NUMBER_SHIFT;
>
> diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h
> index 33653d4ca94f..bc7f815d38ff 100644
> --- a/include/linux/pci-ats.h
> +++ b/include/linux/pci-ats.h
> @@ -40,6 +40,7 @@ static inline int pci_reset_pri(struct pci_dev *pdev)
>
> #ifdef CONFIG_PCI_PASID
>
> +void pci_pasid_init(struct pci_dev *pdev);

Move to drivers/pci/pci.h.

> int pci_enable_pasid(struct pci_dev *pdev, int features);
> void pci_disable_pasid(struct pci_dev *pdev);
> void pci_restore_pasid_state(struct pci_dev *pdev);
> @@ -48,6 +49,10 @@ int pci_max_pasids(struct pci_dev *pdev);
>
> #else /* CONFIG_PCI_PASID */
>
> +static inline void pci_pasid_init(struct pci_dev *pdev)
> +{
> +}
> +
> static inline int pci_enable_pasid(struct pci_dev *pdev, int features)
> {
> return -EINVAL;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 56b55db099fc..27224c0db849 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -459,6 +459,7 @@ struct pci_dev {
> u32 pri_reqs_alloc; /* Number of PRI requests allocated */
> #endif
> #ifdef CONFIG_PCI_PASID
> + u16 pasid_cap; /* PASID Capability offset */
> u16 pasid_features;
> #endif
> #ifdef CONFIG_PCI_P2PDMA
> --
> 2.21.0
>

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