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Subject: Re: [PATCH v3 07/27] ocxl: Add functions to map/unmap LPC memory
From:   "Alastair D'Silva" <alastair@au1.ibm.com>
To:     Andrew Donnellan <ajd@linux.ibm.com>
Cc:     "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
        "Oliver O'Halloran" <oohall@gmail.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Frederic Barrat <fbarrat@linux.ibm.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Ira Weiny <ira.weiny@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Rob Herring <robh@kernel.org>,
        Anton Blanchard <anton@ozlabs.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@linux.vnet.ibm.com>,
        =?ISO-8859-1?Q?C=E9dric?= Le Goater <clg@kaod.org>,
        Anju T Sudhakar <anju@linux.vnet.ibm.com>,
        Hari Bathini <hbathini@linux.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Greg Kurz <groug@kaod.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Alexey Kardashevskiy <aik@ozlabs.ru>,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-nvdimm@lists.01.org, linux-mm@kvack.org
Date:   Mon, 24 Feb 2020 17:08:38 +1100
In-Reply-To: <ebd1c438-1164-8c7c-7067-2389d64740e7@linux.ibm.com>
References: <20200221032720.33893-1-alastair@au1.ibm.com>
         <20200221032720.33893-8-alastair@au1.ibm.com>
         <ebd1c438-1164-8c7c-7067-2389d64740e7@linux.ibm.com>
Organization: IBM Australia
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On Mon, 2020-02-24 at 17:02 +1100, Andrew Donnellan wrote:
> On 21/2/20 2:27 pm, Alastair D'Silva 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/core.c          | 51
> > +++++++++++++++++++++++++++++++
> >   drivers/misc/ocxl/ocxl_internal.h |  3 ++
> >   include/misc/ocxl.h               | 21 +++++++++++++
> >   3 files changed, 75 insertions(+)
> > 
> > diff --git a/drivers/misc/ocxl/core.c b/drivers/misc/ocxl/core.c
> > index 2531c6cf19a0..75ff14e3882a 100644
> > --- a/drivers/misc/ocxl/core.c
> > +++ b/drivers/misc/ocxl/core.c
> > @@ -210,6 +210,56 @@ 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;
> 
> I'd prefer the comparison here to be:
> 
>    afu->config.lpc_mem_size == 0 &&
>      afu->config.special_purpose_mem_size == 0
> 
> so a reader doesn't have to think about what this means.
> 

Ok

> > +
> > +	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 > 0) {
> > +		afu->lpc_res.start = afu->lpc_base_addr + afu-
> > >config.lpc_mem_offset;
> 
> Maybe not for this series - hmm, I wonder if we should print a
> warning 
> somewhere (maybe in read_afu_lpc_memory_info()?) if we see the case 
> where (lpc_mem_offset > 0 && lpc_mem_size == 0). Likewise for
> special 
> purpose?
> 

Sounds reasonable, might as well add it here since there are other LPC
changes.

> > +		afu->lpc_res.end = afu->lpc_res.start + afu-
> > >config.lpc_mem_size - 1;
> > +	}
> > +
> > +	if (afu->config.special_purpose_mem_size > 0) {
> > +		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);
> 
> What's the point of this function? A layer of indirection just in
> case 
> we need it in future?
> 

struct ocxl_afu is opaque outsite the ocxl driver.

> > +
> > +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;
> > +
> > +		// only release the link when the the last consumer
> > calls release
> > +		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 +301,7 @@ 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);
> >   	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 d0c8c4838f42..ce0cac1da416 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 357ef1aadbc0..d8b0b4d46bfb 100644
> > --- a/include/misc/ocxl.h
> > +++ b/include/misc/ocxl.h
> > @@ -203,6 +203,27 @@ int ocxl_irq_set_handler(struct ocxl_context
> > *ctx, int irq_id,
> >   
> >   // AFU Metadata
> >   
> > +/**
> > + * ocxl_afu_map_lpc_mem() - Map the LPC system & special purpose
> > memory for an AFU
> > + * Do not call this during device discovery, as there may me
> > multiple
> 
> be
> 
> > + * 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
> > + *
> > + * Returns 0 on success, negative on failure
> > + */
> > +int ocxl_afu_map_lpc_mem(struct ocxl_afu *afu);
> > +
> > +/**
> > + * ocxl_afu_lpc_mem() - Get the physical address range of LPC
> > memory for an AFU
> > + * @afu: The AFU associated with the LPC memory
> > + *
> > + * Returns a pointer to the resource struct for the physical
> > address range
> > + */
> > +struct resource *ocxl_afu_lpc_mem(struct ocxl_afu *afu);
> > +
> >   /**
> >    * ocxl_afu_config() - Get a pointer to the config for an AFU
> >    * @afu: a pointer to the AFU to get the config for
> > 
-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819