RE: [PATCH v2 07/27] ocxl: Add functions to map/unmap LPC memory

["Alastair D'Silva" <alastair@au1.ibm.com>]

On Mon, 2020-02-03 at 12:49 +0000, Jonathan Cameron wrote:
> On Tue, 3 Dec 2019 14:46:35 +1100
> Alastair D'Silva <alastair@au1.ibm.com> wrote:
> 
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > Add functions to map/unmap LPC memory
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > ---
> >  drivers/misc/ocxl/config.c        |  4 +++
> >  drivers/misc/ocxl/core.c          | 50
> > +++++++++++++++++++++++++++++++
> >  drivers/misc/ocxl/ocxl_internal.h |  3 ++
> >  include/misc/ocxl.h               | 18 +++++++++++
> >  4 files changed, 75 insertions(+)
> > 
> > diff --git a/drivers/misc/ocxl/config.c
> > b/drivers/misc/ocxl/config.c
> > index c8e19bfb5ef9..fb0c3b6f8312 100644
> > --- a/drivers/misc/ocxl/config.c
> > +++ b/drivers/misc/ocxl/config.c
> > @@ -568,6 +568,10 @@ static int read_afu_lpc_memory_info(struct
> > pci_dev *dev,
> >  		afu->special_purpose_mem_size =
> >  			total_mem_size - lpc_mem_size;
> >  	}
> > +
> > +	dev_info(&dev->dev, "Probed LPC memory of %#llx bytes and
> > special purpose memory of %#llx bytes\n",
> > +		afu->lpc_mem_size, afu->special_purpose_mem_size);
> > +
> 
> If we are being fussy, this block has nothing todo with the rest of
> the patch
> so we should be seeing it here.

Agreed

> 
> >  	return 0;
> >  }
> >  
> > diff --git a/drivers/misc/ocxl/core.c b/drivers/misc/ocxl/core.c
> > index 2531c6cf19a0..98611faea219 100644
> > --- a/drivers/misc/ocxl/core.c
> > +++ b/drivers/misc/ocxl/core.c
> > @@ -210,6 +210,55 @@ static void unmap_mmio_areas(struct ocxl_afu
> > *afu)
> >  	release_fn_bar(afu->fn, afu->config.global_mmio_bar);
> >  }
> >  
> > +int ocxl_afu_map_lpc_mem(struct ocxl_afu *afu)
> > +{
> > +	struct pci_dev *dev = to_pci_dev(afu->fn->dev.parent);
> > +
> > +	if ((afu->config.lpc_mem_size + afu-
> > >config.special_purpose_mem_size) == 0)
> > +		return 0;
> > +
> > +	afu->lpc_base_addr = ocxl_link_lpc_map(afu->fn->link, dev);
> > +	if (afu->lpc_base_addr == 0)
> > +		return -EINVAL;
> > +
> > +	if (afu->config.lpc_mem_size) {
> 
> I was happy with the explicit check on 0 above, but we should be
> consistent.  Either
> we make use of 0 == false, or we don't and explicitly check vs 0.
> 
> Hence
> 
> if (afu->config.pc_mem_size != 0) { 
> 
> here or
> 
> if (!(afu->config.pc_mem_size + afu-
> >config.special_purpose_mem_size))
> 	return 0;
> 
> above.

This feels a bit niggly, but sure, changed to a '> 0' check.

> 
> > +		afu->lpc_res.start = afu->lpc_base_addr + afu-
> > >config.lpc_mem_offset;
> > +		afu->lpc_res.end = afu->lpc_res.start + afu-
> > >config.lpc_mem_size - 1;
> > +	}
> > +
> > +	if (afu->config.special_purpose_mem_size) {
> > +		afu->special_purpose_res.start = afu->lpc_base_addr +
> > +						 afu-
> > >config.special_purpose_mem_offset;
> > +		afu->special_purpose_res.end = afu-
> > >special_purpose_res.start +
> > +					       afu-
> > >config.special_purpose_mem_size - 1;
> > +	}
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(ocxl_afu_map_lpc_mem);
> > +
> > +struct resource *ocxl_afu_lpc_mem(struct ocxl_afu *afu)
> > +{
> > +	return &afu->lpc_res;
> > +}
> > +EXPORT_SYMBOL_GPL(ocxl_afu_lpc_mem);
> > +
> > +static void unmap_lpc_mem(struct ocxl_afu *afu)
> > +{
> > +	struct pci_dev *dev = to_pci_dev(afu->fn->dev.parent);
> > +
> > +	if (afu->lpc_res.start || afu->special_purpose_res.start) {
> > +		void *link = afu->fn->link;
> > +
> > +		ocxl_link_lpc_release(link, dev);
> > +
> > +		afu->lpc_res.start = 0;
> > +		afu->lpc_res.end = 0;
> > +		afu->special_purpose_res.start = 0;
> > +		afu->special_purpose_res.end = 0;
> > +	}
> > +}
> > +
> >  static int configure_afu(struct ocxl_afu *afu, u8 afu_idx, struct
> > pci_dev *dev)
> >  {
> >  	int rc;
> > @@ -251,6 +300,7 @@ static int configure_afu(struct ocxl_afu *afu,
> > u8 afu_idx, struct pci_dev *dev)
> >  
> >  static void deconfigure_afu(struct ocxl_afu *afu)
> >  {
> > +	unmap_lpc_mem(afu);
> 
> Hmm. This breaks the existing balance between configure_afu and
> deconfigure_afu.
> 
> Given comments below on why we don't do map_lpc_mem in the afu bring
> up
> (as it's a shared operation) it seems to me that we should be doing
> this
> outside of the afu deconfigure.  Perhaps ocxl_function_close is
> appropriate?
> I don't know this infrastructure well enough to be sure.
> 
> If it does need to be here, then a comment to give more info on
> why would be great!
> 

Sure, I've added a comment in unmap_lpc_mem explaining that lpc_release
only releases the memory on the link when the last consumer calls
release.

It's in deconfigure_afu as the LPC memory is registered and reported
per-AFU (even though it has to be allocated all at once across the
link).

> >  	unmap_mmio_areas(afu);
> >  	reclaim_afu_pasid(afu);
> >  	reclaim_afu_actag(afu);
> > diff --git a/drivers/misc/ocxl/ocxl_internal.h
> > b/drivers/misc/ocxl/ocxl_internal.h
> > index 20b417e00949..9f4b47900e62 100644
> > --- a/drivers/misc/ocxl/ocxl_internal.h
> > +++ b/drivers/misc/ocxl/ocxl_internal.h
> > @@ -52,6 +52,9 @@ struct ocxl_afu {
> >  	void __iomem *global_mmio_ptr;
> >  	u64 pp_mmio_start;
> >  	void *private;
> > +	u64 lpc_base_addr; /* Covers both LPC & special purpose memory
> > */
> > +	struct resource lpc_res;
> > +	struct resource special_purpose_res;
> >  };
> >  
> >  enum ocxl_context_status {
> > diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
> > index 06dd5839e438..6f7c02f0d5e3 100644
> > --- a/include/misc/ocxl.h
> > +++ b/include/misc/ocxl.h
> > @@ -212,6 +212,24 @@ int ocxl_irq_set_handler(struct ocxl_context
> > *ctx, int irq_id,
> >  
> >  // AFU Metadata
> >  
> > +/**
> > + * Map the LPC system & special purpose memory for an AFU
> > + *
> > + * Do not call this during device discovery, as there may me
> > multiple
> > + * devices on a link, and the memory is mapped for the whole link,
> > not
> > + * just one device. It should only be called after all devices
> > have
> > + * registered their memory on the link.
> > + *
> > + * afu: The AFU that has the LPC memory to map
> Run kernel-doc over these files and fix all the errors + warnings.
> 
Ok.

> @afu: ..
> 
> and missing function name etc.
> 
> 
> > + */
> > +extern int ocxl_afu_map_lpc_mem(struct ocxl_afu *afu);
> > +
> > +/**
> > + * Get the physical address range of LPC memory for an AFU
> > + * afu: The AFU associated with the LPC memory
> > + */
> > +extern struct resource *ocxl_afu_lpc_mem(struct ocxl_afu *afu);
> > +
> >  /**
> >   * Get a pointer to the config for an AFU
> >   *
-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819