Re: [PATCH v2 06/27] ocxl: Tally up the LPC memory on a link & allow it to be mapped

Frederic Barrat
2020-01-09T14:48:29Z

Le 03/12/2019 à 04:46, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
>
> Tally up the LPC memory on an OpenCAPI link & allow it to be mapped
>
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
> 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..d8503f0dc6ec 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;
> + 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;
> + u64 lpc_mem;
> +
> + mutex_lock(&link->lpc_mem_lock);
> + if (link->lpc_mem) {
> + lpc_mem = link->lpc_mem;
> +
> + link->lpc_consumers++;
> + mutex_unlock(&link->lpc_mem_lock);
> + return lpc_mem;
> + }
> +
> + link->lpc_mem = pnv_ocxl_platform_lpc_setup(pdev, link->lpc_mem_sz);
> + if (link->lpc_mem)
> + link->lpc_consumers++;

So if we fail to setup the lpc access in opal, we don't increment
link->lpc_consumers and we shouldn't call ocxl_link_lpc_release(). Is
that always true? Risk is to trigger the warning in
ocxl_link_lpc_release(). So maybe we should check link->lpc_mem first in
ocxl_link_lpc_release() and exit early if no memory is mapped. It would
probably avoid hitting the WARN on an error path for example.

Fred

> + lpc_mem = link->lpc_mem;
> + mutex_unlock(&link->lpc_mem_lock);
> +
> + return 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);
> + 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 97415afd79f3..20b417e00949 100644
> --- a/drivers/misc/ocxl/ocxl_internal.h
> +++ b/drivers/misc/ocxl/ocxl_internal.h
> @@ -141,4 +141,37 @@ 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 amount of memory to increment by
> + *
> + * Return 0 on success, negative 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 bust 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
> + */
> +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_ */
>