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SubjectRE: [PATCH v4 07/25] ocxl: Add functions to map/unmap LPC memory
Date

> -----Original Message-----
> From: Dan Williams <dan.j.williams@intel.com>
> Sent: Wednesday, 1 April 2020 7:49 PM
> To: Alastair D'Silva <alastair@d-silva.org>
> 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>;
> Andrew Donnellan <ajd@linux.ibm.com>; Arnd Bergmann
> <arnd@arndb.de>; Greg Kroah-Hartman <gregkh@linuxfoundation.org>;
> 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>; Cédric 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 Mailing List <linux-kernel@vger.kernel.org>;
> linuxppc-dev <linuxppc-dev@lists.ozlabs.org>; linux-nvdimm <linux-
> nvdimm@lists.01.org>; Linux MM <linux-mm@kvack.org>
> Subject: Re: [PATCH v4 07/25] ocxl: Add functions to map/unmap LPC
> memory
>
> On Sun, Mar 29, 2020 at 10:23 PM Alastair D'Silva <alastair@d-silva.org>
> wrote:
> >
> > Add functions to map/unmap LPC memory
> >
>
> "map memory" is an overloaded term. I'm guessing this patch has nothing to
> do with mapping memory in the MMU. Is it updating hardware resource
> decoders to start claiming address space that was allocated previously?
>

It's similar to MMIO - these calls end up setting up a BAR which places the LPC
memory into a physical memory range addressable by the kernel.

> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>
> > ---
> > 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;
> > +
> > + 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;
> > + 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);
> > +
> > +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 2d7575225bd7..7b975a89db7b 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
>
> s/me/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
> > --
> > 2.24.1
> >



--
Alastair D'Silva mob: 0423 762 819
skype: alastair_dsilva msn: alastair@d-silva.org
blog: http://alastair.d-silva.org Twitter: @EvilDeece

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