Re: [PATCH v5 2/7] PCI/ATS: Initialize PRI in pci_ats_init()

From: Bjorn Helgaas
Date: Mon Aug 12 2019 - 16:04:38 EST

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On Thu, Aug 01, 2019 at 05:05:59PM -0700, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
>
> Currently, PRI Capability checks are repeated across all PRI API's.
> Instead, cache the capability check result in pci_pri_init() and use it
> in other PRI API's. Also, since PRI is a shared resource between PF/VF,
> initialize default values for common PRI features in pci_pri_init().

This patch does two things, and it would be better if they were split:

1) Cache the PRI capability offset
2) Separate the PF and VF paths

> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> ---
> drivers/pci/ats.c | 80 ++++++++++++++++++++++++++++-------------
> include/linux/pci-ats.h | 5 +++
> include/linux/pci.h | 1 +
> 3 files changed, 61 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
> index cdd936d10f68..280be911f190 100644
> --- a/drivers/pci/ats.c
> +++ b/drivers/pci/ats.c
> @@ -28,6 +28,8 @@ void pci_ats_init(struct pci_dev *dev)
> return;
>
> dev->ats_cap = pos;
> +
> + pci_pri_init(dev);
> }
>
> /**
> @@ -170,36 +172,72 @@ int pci_ats_page_aligned(struct pci_dev *pdev)
> EXPORT_SYMBOL_GPL(pci_ats_page_aligned);
>
> #ifdef CONFIG_PCI_PRI
> +
> +void pci_pri_init(struct pci_dev *pdev)
> +{
> + u32 max_requests;
> + int pos;
> +
> + /*
> + * As per PCIe r4.0, sec 9.3.7.11, only PF is permitted to
> + * implement PRI and all associated VFs can only use it.
> + * Since PF already initialized the PRI parameters there is
> + * no need to proceed further.
> + */
> + if (pdev->is_virtfn)
> + return;
> +
> + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
> + if (!pos)
> + return;
> +
> + pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests);
> +
> + /*
> + * Since PRI is a shared resource between PF and VF, we must not
> + * configure Outstanding Page Allocation Quota as a per device
> + * resource in pci_enable_pri(). So use maximum value possible
> + * as default value.
> + */
> + pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, max_requests);
> +
> + pdev->pri_reqs_alloc = max_requests;
> + pdev->pri_cap = pos;
> +}
> +
> /**
> * pci_enable_pri - Enable PRI capability
> * @ pdev: PCI device structure
> *
> * Returns 0 on success, negative value on error
> + *
> + * TODO: Since PRI is a shared resource between PF/VF, don't update
> + * Outstanding Page Allocation Quota in the same API as a per device
> + * feature.
> */
> int pci_enable_pri(struct pci_dev *pdev, u32 reqs)
> {
> u16 control, status;
> u32 max_requests;
> - int pos;
>
> if (WARN_ON(pdev->pri_enabled))
> return -EBUSY;
>
> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
> - if (!pos)
> + if (!pdev->pri_cap)
> return -EINVAL;
>
> - pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status);
> + pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_STATUS, &status);
> if (!(status & PCI_PRI_STATUS_STOPPED))
> return -EBUSY;
>
> - pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests);
> + pci_read_config_dword(pdev, pdev->pri_cap + PCI_PRI_MAX_REQ,
> + &max_requests);
> reqs = min(max_requests, reqs);
> pdev->pri_reqs_alloc = reqs;
> - pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, reqs);
> + pci_write_config_dword(pdev, pdev->pri_cap + PCI_PRI_ALLOC_REQ, reqs);

The comment above says "don't update Outstanding Page Allocation
Quota" but it looks like that's what this is doing.

> control = PCI_PRI_CTRL_ENABLE;
> - pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
> + pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control);
>
> pdev->pri_enabled = 1;
>
> @@ -216,18 +254,16 @@ EXPORT_SYMBOL_GPL(pci_enable_pri);
> void pci_disable_pri(struct pci_dev *pdev)
> {
> u16 control;
> - int pos;
>
> if (WARN_ON(!pdev->pri_enabled))
> return;
>
> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
> - if (!pos)
> + if (!pdev->pri_cap)
> return;
>
> - pci_read_config_word(pdev, pos + PCI_PRI_CTRL, &control);
> + pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, &control);
> control &= ~PCI_PRI_CTRL_ENABLE;
> - pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
> + pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control);
>
> pdev->pri_enabled = 0;
> }
> @@ -241,17 +277,15 @@ void pci_restore_pri_state(struct pci_dev *pdev)
> {
> u16 control = PCI_PRI_CTRL_ENABLE;
> u32 reqs = pdev->pri_reqs_alloc;
> - int pos;
>
> if (!pdev->pri_enabled)
> return;
>
> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
> - if (!pos)
> + if (!pdev->pri_cap)
> return;
>
> - pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, reqs);
> - pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
> + pci_write_config_dword(pdev, pdev->pri_cap + PCI_PRI_ALLOC_REQ, reqs);
> + pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control);
> }
> EXPORT_SYMBOL_GPL(pci_restore_pri_state);
>
> @@ -265,17 +299,15 @@ EXPORT_SYMBOL_GPL(pci_restore_pri_state);
> int pci_reset_pri(struct pci_dev *pdev)
> {
> u16 control;
> - int pos;
>
> if (WARN_ON(pdev->pri_enabled))
> return -EBUSY;
>
> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
> - if (!pos)
> + if (!pdev->pri_cap)
> return -EINVAL;
>
> control = PCI_PRI_CTRL_RESET;
> - pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
> + pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control);
>
> return 0;
> }
> @@ -410,13 +442,11 @@ EXPORT_SYMBOL_GPL(pci_pasid_features);
> int pci_prg_resp_pasid_required(struct pci_dev *pdev)
> {
> u16 status;
> - int pos;
>
> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
> - if (!pos)
> + if (!pdev->pri_cap)
> return 0;
>
> - pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status);
> + pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_STATUS, &status);
>
> if (status & PCI_PRI_STATUS_PASID)
> return 1;
> diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h
> index 1a0bdaee2f32..33653d4ca94f 100644
> --- a/include/linux/pci-ats.h
> +++ b/include/linux/pci-ats.h
> @@ -6,6 +6,7 @@
>
> #ifdef CONFIG_PCI_PRI
>
> +void pci_pri_init(struct pci_dev *pdev);

I think this could be moved to drivers/pci/pci.h, since it doesn't
need to be visible outside drivers/pci/.

> int pci_enable_pri(struct pci_dev *pdev, u32 reqs);
> void pci_disable_pri(struct pci_dev *pdev);
> void pci_restore_pri_state(struct pci_dev *pdev);
> @@ -13,6 +14,10 @@ int pci_reset_pri(struct pci_dev *pdev);
>
> #else /* CONFIG_PCI_PRI */
>
> +static inline void pci_pri_init(struct pci_dev *pdev)
> +{
> +}
> +
> static inline int pci_enable_pri(struct pci_dev *pdev, u32 reqs)
> {
> return -ENODEV;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 9e700d9f9f28..56b55db099fc 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -455,6 +455,7 @@ struct pci_dev {
> atomic_t ats_ref_cnt; /* Number of VFs with ATS enabled */
> #endif
> #ifdef CONFIG_PCI_PRI
> + u16 pri_cap; /* PRI Capability offset */
> u32 pri_reqs_alloc; /* Number of PRI requests allocated */
> #endif
> #ifdef CONFIG_PCI_PASID
> --
> 2.21.0
>

Next message: Bjorn Helgaas: "Re: [PATCH v5 3/7] PCI/ATS: Initialize PASID in pci_ats_init()"
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