Re: [PATCH v4 06/25] ocxl: Tally up the LPC memory on a link & allow it to be mapped

[Dan Williams]

On Sun, Mar 29, 2020 at 10:53 PM Alastair D'Silva <alastair@xxxxxxxxxxx> wrote:
>
> OpenCAPI LPC memory is allocated per link, but each link supports
> multiple AFUs, and each AFU can have LPC memory assigned to it.

Is there an OpenCAPI primer to decode these objects and their
associations that I can reference?


>
> This patch tallys the memory for all AFUs on a link, allowing it
> to be mapped in a single operation after the AFUs have been
> enumerated.
>
> Signed-off-by: Alastair D'Silva <alastair@xxxxxxxxxxx>
> ---
>  drivers/misc/ocxl/core.c          | 10 ++++++
>  drivers/misc/ocxl/link.c          | 60 +++++++++++++++++++++++++++++++
>  drivers/misc/ocxl/ocxl_internal.h | 33 +++++++++++++++++
>  3 files changed, 103 insertions(+)
>
> diff --git a/drivers/misc/ocxl/core.c b/drivers/misc/ocxl/core.c
> index b7a09b21ab36..2531c6cf19a0 100644
> --- a/drivers/misc/ocxl/core.c
> +++ b/drivers/misc/ocxl/core.c
> @@ -230,8 +230,18 @@ static int configure_afu(struct ocxl_afu *afu, u8 afu_idx, struct pci_dev *dev)
>         if (rc)
>                 goto err_free_pasid;
>
> +       if (afu->config.lpc_mem_size || afu->config.special_purpose_mem_size) {
> +               rc = ocxl_link_add_lpc_mem(afu->fn->link, afu->config.lpc_mem_offset,
> +                                          afu->config.lpc_mem_size +
> +                                          afu->config.special_purpose_mem_size);
> +               if (rc)
> +                       goto err_free_mmio;
> +       }
> +
>         return 0;
>
> +err_free_mmio:
> +       unmap_mmio_areas(afu);
>  err_free_pasid:
>         reclaim_afu_pasid(afu);
>  err_free_actag:
> diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> index 58d111afd9f6..af119d3ef79a 100644
> --- a/drivers/misc/ocxl/link.c
> +++ b/drivers/misc/ocxl/link.c
> @@ -84,6 +84,11 @@ struct ocxl_link {
>         int dev;
>         atomic_t irq_available;
>         struct spa *spa;
> +       struct mutex lpc_mem_lock; /* protects lpc_mem & lpc_mem_sz */
> +       u64 lpc_mem_sz; /* Total amount of LPC memory presented on the link */
> +       u64 lpc_mem;
> +       int lpc_consumers;
> +
>         void *platform_data;
>  };
>  static struct list_head links_list = LIST_HEAD_INIT(links_list);
> @@ -396,6 +401,8 @@ static int alloc_link(struct pci_dev *dev, int PE_mask, struct ocxl_link **out_l
>         if (rc)
>                 goto err_spa;
>
> +       mutex_init(&link->lpc_mem_lock);
> +
>         /* platform specific hook */
>         rc = pnv_ocxl_spa_setup(dev, link->spa->spa_mem, PE_mask,
>                                 &link->platform_data);
> @@ -711,3 +718,56 @@ void ocxl_link_free_irq(void *link_handle, int hw_irq)
>         atomic_inc(&link->irq_available);
>  }
>  EXPORT_SYMBOL_GPL(ocxl_link_free_irq);
> +
> +int ocxl_link_add_lpc_mem(void *link_handle, u64 offset, u64 size)
> +{
> +       struct ocxl_link *link = (struct ocxl_link *)link_handle;
> +
> +       // Check for overflow
> +       if (offset > (offset + size))
> +               return -EINVAL;
> +
> +       mutex_lock(&link->lpc_mem_lock);
> +       link->lpc_mem_sz = max(link->lpc_mem_sz, offset + size);
> +
> +       mutex_unlock(&link->lpc_mem_lock);
> +
> +       return 0;
> +}
> +
> +u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev)
> +{
> +       struct ocxl_link *link = (struct ocxl_link *)link_handle;
> +
> +       mutex_lock(&link->lpc_mem_lock);
> +
> +       if (!link->lpc_mem)
> +               link->lpc_mem = pnv_ocxl_platform_lpc_setup(pdev, link->lpc_mem_sz);
> +
> +       if (link->lpc_mem)
> +               link->lpc_consumers++;
> +       mutex_unlock(&link->lpc_mem_lock);
> +
> +       return link->lpc_mem;
> +}
> +
> +void ocxl_link_lpc_release(void *link_handle, struct pci_dev *pdev)
> +{
> +       struct ocxl_link *link = (struct ocxl_link *)link_handle;
> +
> +       mutex_lock(&link->lpc_mem_lock);
> +
> +       if (!link->lpc_mem) {
> +               mutex_unlock(&link->lpc_mem_lock);
> +               return;
> +       }
> +
> +       WARN_ON(--link->lpc_consumers < 0);
> +
> +       if (link->lpc_consumers == 0) {
> +               pnv_ocxl_platform_lpc_release(pdev);
> +               link->lpc_mem = 0;
> +       }
> +
> +       mutex_unlock(&link->lpc_mem_lock);
> +}
> diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
> index 198e4e4bc51d..2d7575225bd7 100644
> --- a/drivers/misc/ocxl/ocxl_internal.h
> +++ b/drivers/misc/ocxl/ocxl_internal.h
> @@ -142,4 +142,37 @@ int ocxl_irq_offset_to_id(struct ocxl_context *ctx, u64 offset);
>  u64 ocxl_irq_id_to_offset(struct ocxl_context *ctx, int irq_id);
>  void ocxl_afu_irq_free_all(struct ocxl_context *ctx);
>
> +/**
> + * ocxl_link_add_lpc_mem() - Increment the amount of memory required by an OpenCAPI link
> + *
> + * @link_handle: The OpenCAPI link handle
> + * @offset: The offset of the memory to add
> + * @size: The number of bytes to increment memory on the link by
> + *
> + * Returns 0 on success, -EINVAL on overflow
> + */
> +int ocxl_link_add_lpc_mem(void *link_handle, u64 offset, u64 size);
> +
> +/**
> + * ocxl_link_lpc_map() - Map the LPC memory for an OpenCAPI device
> + * Since LPC memory belongs to a link, the whole LPC memory available
> + * on the link must be mapped in order to make it accessible to a device.
> + * @link_handle: The OpenCAPI link handle
> + * @pdev: A device that is on the link
> + *
> + * Returns the address of the mapped LPC memory, or 0 on error
> + */
> +u64 ocxl_link_lpc_map(void *link_handle, struct pci_dev *pdev);
> +
> +/**
> + * ocxl_link_lpc_release() - Release the LPC memory device for an OpenCAPI device
> + *
> + * Offlines LPC memory on an OpenCAPI link for a device. If this is the
> + * last device on the link to release the memory, unmap it from the link.
> + *
> + * @link_handle: The OpenCAPI link handle
> + * @pdev: A device that is on the link
> + */
> +void ocxl_link_lpc_release(void *link_handle, struct pci_dev *pdev);
> +
>  #endif /* _OCXL_INTERNAL_H_ */
> --
> 2.24.1
>