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

[Alastair D'Silva]

On Mon, 2020-02-03 at 12:37 +0000, Jonathan Cameron wrote:
> On Tue, 3 Dec 2019 14:46:34 +1100
> Alastair D'Silva <alastair@xxxxxxxxxxx> wrote:
> 
> > From: Alastair D'Silva <alastair@xxxxxxxxxxx>
> > 
> > Tally up the LPC memory on an OpenCAPI link & allow it to be mapped
> > 
> > Signed-off-by: Alastair D'Silva <alastair@xxxxxxxxxxx>
> Hi Alastair,
> 
> A few trivial comments inline.
> 
> Jonathan
> 
> > ---
> >  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;
> 
> Always a good idea to explicitly document what a lock is intended to
> protect.
> 
Ok

> > +	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
> 
> Stray c++ style comment.
> 
This is permitted in powerpc.

> > +	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) {
> 
> If you don't modify this later in the series (I haven't read it all
> yet :),
> it rather feels like it would be more compact and just as readable as
> something like...
> 
> 	if (!link->lpc_mem)
> 		link->lpc_mem = pnv_ocxl...
> 
> 	if (link->lpc_mem)
> 		link->lpc_consumers++;
> 	mutex_unlock(&link->lpc_mem_lock);
> 		
> 	return link->lpc_mem;
> 

Agreed, thanks.

> > +		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++;
> > +	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.
> 
> must

Whoops :)
> 
> > + *
> > + * @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_ */

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819