linux-kernel - Re: [PATCH v3 03/27] powerpc: Map & release OpenCAPI LPC memory

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Message-Id: <20f0a729962c1fe58f34f500c2666b4516073508.camel@au1.ibm.com>
Date:   Wed, 26 Feb 2020 11:19:05 +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 03/27] powerpc: Map & release OpenCAPI LPC memory

On Tue, 2020-02-25 at 11:02 +0100, Frederic Barrat wrote:
> 
> Le 21/02/2020 à 04:26, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@...ilva.org>
> > 
> > This patch adds platform support to map & release LPC memory.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
> > ---
> >   arch/powerpc/include/asm/pnv-ocxl.h   |  4 +++
> >   arch/powerpc/platforms/powernv/ocxl.c | 43
> > +++++++++++++++++++++++++++
> >   2 files changed, 47 insertions(+)
> > 
> > diff --git a/arch/powerpc/include/asm/pnv-ocxl.h
> > b/arch/powerpc/include/asm/pnv-ocxl.h
> > index 7de82647e761..0b2a6707e555 100644
> > --- a/arch/powerpc/include/asm/pnv-ocxl.h
> > +++ b/arch/powerpc/include/asm/pnv-ocxl.h
> > @@ -32,5 +32,9 @@ extern int pnv_ocxl_spa_remove_pe_from_cache(void
> > *platform_data, int pe_handle)
> >   
> >   extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
> >   extern void pnv_ocxl_free_xive_irq(u32 irq);
> > +#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
> > +u64 pnv_ocxl_platform_lpc_setup(struct pci_dev *pdev, u64 size);
> > +void pnv_ocxl_platform_lpc_release(struct pci_dev *pdev);
> > +#endif
> 
> This breaks the compilation of the ocxl driver if
> CONFIG_MEMORY_HOTPLUG=n
> 
> Those functions still make sense even without memory hotplug, for 
> example in the context of the implementation you had to access
> opencapi 
> LPC memory through mmap(). The #ifdef is really needed only around
> the 
> check_hotplug_memory_addressable() call.
> 
>    Fred

Hmm, we do still need sparsemem though. Let me think about his some
more.

> 
> 
> >   #endif /* _ASM_PNV_OCXL_H */
> > diff --git a/arch/powerpc/platforms/powernv/ocxl.c
> > b/arch/powerpc/platforms/powernv/ocxl.c
> > index 8c65aacda9c8..f2edbcc67361 100644
> > --- a/arch/powerpc/platforms/powernv/ocxl.c
> > +++ b/arch/powerpc/platforms/powernv/ocxl.c
> > @@ -475,6 +475,49 @@ void pnv_ocxl_spa_release(void *platform_data)
> >   }
> >   EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
> >   
> > +#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
> > +u64 pnv_ocxl_platform_lpc_setup(struct pci_dev *pdev, u64 size)
> > +{
> > +	struct pci_controller *hose = pci_bus_to_host(pdev->bus);
> > +	struct pnv_phb *phb = hose->private_data;
> > +	u32 bdfn = pci_dev_id(pdev);
> > +	__be64 base_addr_be64;
> > +	u64 base_addr;
> > +	int rc;
> > +
> > +	rc = opal_npu_mem_alloc(phb->opal_id, bdfn, size,
> > &base_addr_be64);
> > +	if (rc) {
> > +		dev_warn(&pdev->dev,
> > +			 "OPAL could not allocate LPC memory, rc=%d\n",
> > rc);
> > +		return 0;
> > +	}
> > +
> > +	base_addr = be64_to_cpu(base_addr_be64);
> > +
> > +	rc = check_hotplug_memory_addressable(base_addr >> PAGE_SHIFT,
> > +					      size >> PAGE_SHIFT);
> > +	if (rc)
> > +		return 0;
> > +
> > +	return base_addr;
> > +}
> > +EXPORT_SYMBOL_GPL(pnv_ocxl_platform_lpc_setup);
> > +
> > +void pnv_ocxl_platform_lpc_release(struct pci_dev *pdev)
> > +{
> > +	struct pci_controller *hose = pci_bus_to_host(pdev->bus);
> > +	struct pnv_phb *phb = hose->private_data;
> > +	u32 bdfn = pci_dev_id(pdev);
> > +	int rc;
> > +
> > +	rc = opal_npu_mem_release(phb->opal_id, bdfn);
> > +	if (rc)
> > +		dev_warn(&pdev->dev,
> > +			 "OPAL reported rc=%d when releasing LPC
> > memory\n", rc);
> > +}
> > +EXPORT_SYMBOL_GPL(pnv_ocxl_platform_lpc_release);
> > +#endif
> > +
> >   int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int
> > pe_handle)
> >   {
> >   	struct spa_data *data = (struct spa_data *) platform_data;
> > 
-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819