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Date: Wed, 26 Feb 2020 11:29:16 +1100
From: "Alastair D'Silva" <alastair@....ibm.com>
To: Frederic Barrat <fbarrat@...ux.ibm.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
"Oliver O'Halloran" <oohall@...il.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>,
Andrew Donnellan <ajd@...ux.ibm.com>,
Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Dan Williams <dan.j.williams@...el.com>,
Vishal Verma <vishal.l.verma@...el.com>,
Dave Jiang <dave.jiang@...el.com>,
Ira Weiny <ira.weiny@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
Rob Herring <robh@...nel.org>,
Anton Blanchard <anton@...abs.org>,
Krzysztof Kozlowski <krzk@...nel.org>,
Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
Cédric Le Goater <clg@...d.org>,
Anju T Sudhakar <anju@...ux.vnet.ibm.com>,
Hari Bathini <hbathini@...ux.ibm.com>,
Thomas Gleixner <tglx@...utronix.de>,
Greg Kurz <groug@...d.org>,
Nicholas Piggin <npiggin@...il.com>,
Masahiro Yamada <yamada.masahiro@...ionext.com>,
Alexey Kardashevskiy <aik@...abs.ru>,
linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-nvdimm@...ts.01.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 06/27] ocxl: Tally up the LPC memory on a link &
allow it to be mapped
On Tue, 2020-02-25 at 17:30 +0100, Frederic Barrat wrote:
>
> Le 21/02/2020 à 04:26, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@...ilva.org>
> >
> > Tally up the LPC memory on an OpenCAPI link & allow it to be mapped
> >
> > Signed-off-by: Alastair D'Silva <alastair@...ilva.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
>
>
Ok, this makes sense.
>
> > + 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_ */
> >
--
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819
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