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    SubjectRe: [PATCH v3 06/27] ocxl: Tally up the LPC memory on a link & allow it to be mapped
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    Le 21/02/2020 à 04:26, 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 | 53 +++++++++++++++++++++++++++++++
    > drivers/misc/ocxl/ocxl_internal.h | 33 +++++++++++++++++++
    > 3 files changed, 96 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..1e039cc5ebe5 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 +718,49 @@ 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);
    > + WARN_ON(--link->lpc_consumers < 0);


    Here, we always decrement the lpc_consumers count. However, it was only
    incremented if the mapping was setup correctly in opal.

    We could arguably claim that ocxl_link_lpc_release() should only be
    called if ocxl_link_lpc_map() succeeded, but it would make error path
    handling easier if we only decrement the lpc_consumers count if
    link->lpc_mem is set. So that we can just call ocxl_link_lpc_release()
    in error paths without having to worry about triggering the WARN_ON message.

    Fred



    > + 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..d0c8c4838f42 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 amount of memory to increment by
    > + *
    > + * Returns 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 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_ */
    >

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