linux-kernel - Re: [PATCH 2/5] powerpc: Map & release OpenCAPI LPC memory

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Date:   Thu, 19 Sep 2019 10:58:07 +1000
From:   "Alastair D'Silva" <alastair@....ibm.com>
To:     Frederic Barrat <fbarrat@...ux.ibm.com>
Cc:     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>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        Allison Randal <allison@...utok.net>,
        Anju T Sudhakar <anju@...ux.vnet.ibm.com>,
        Vaibhav Jain <vaibhav@...ux.ibm.com>,
        Cédric Le Goater <clg@...d.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        David Gibson <david@...son.dropbear.id.au>,
        Alexey Kardashevskiy <aik@...abs.ru>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Nicholas Piggin <npiggin@...il.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] powerpc: Map & release OpenCAPI LPC memory

On Wed, 2019-09-18 at 16:03 +0200, Frederic Barrat wrote:
> 
> Le 17/09/2019 à 03:42, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@...ilva.org>
> > 
> > Map & release OpenCAPI LPC memory.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
> > ---
> >   arch/powerpc/include/asm/pnv-ocxl.h   |  2 ++
> >   arch/powerpc/platforms/powernv/ocxl.c | 42
> > +++++++++++++++++++++++++++
> >   2 files changed, 44 insertions(+)
> > 
> > diff --git a/arch/powerpc/include/asm/pnv-ocxl.h
> > b/arch/powerpc/include/asm/pnv-ocxl.h
> > index 7de82647e761..f8f8ffb48aa8 100644
> > --- a/arch/powerpc/include/asm/pnv-ocxl.h
> > +++ b/arch/powerpc/include/asm/pnv-ocxl.h
> > @@ -32,5 +32,7 @@ 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);
> > +extern u64 pnv_ocxl_platform_lpc_setup(struct pci_dev *pdev, u64
> > size);
> > +extern void pnv_ocxl_platform_lpc_release(struct pci_dev *pdev);
> >   
> >   #endif /* _ASM_PNV_OCXL_H */
> > diff --git a/arch/powerpc/platforms/powernv/ocxl.c
> > b/arch/powerpc/platforms/powernv/ocxl.c
> > index 8c65aacda9c8..81393728d6a3 100644
> > --- a/arch/powerpc/platforms/powernv/ocxl.c
> > +++ b/arch/powerpc/platforms/powernv/ocxl.c
> > @@ -475,6 +475,48 @@ void pnv_ocxl_spa_release(void *platform_data)
> >   }
> >   EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
> >   
> > +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;
> > +	struct pci_dn *pdn = pci_get_pdn(pdev);
> > +	u32 bdfn = (pdn->busno << 8) | pdn->devfn;
> 
> We can spare a call to pci_get_pdn() with
> bdfn = (pdev->bus->number << 8) | pdev->devfn;
> 

Ok.

> 
> > +	u64 base_addr = 0;
> > +
> > +	int rc = opal_npu_mem_alloc(phb->opal_id, bdfn, size,
> > &base_addr);
> > +
> > +	WARN_ON(rc);
> 
> Instead of a WARN, we should catch the error and return a null
> address 
> to the caller.
> 

base_addr will be 0 in the error case, are you suggesting we just
remove the WARN_ON()?

> > +
> > +	base_addr = be64_to_cpu(base_addr);
> > +
> > +	rc = check_hotplug_memory_addressable(base_addr, base_addr +
> > size);
> 
> That code is missing?
> 

That's added in the following patch on the mm list:
 [PATCH v3 1/2] memory_hotplug: Add a bounds check to
check_hotplug_memory_range()

> 
> > +	if (rc) {
> > +		dev_warn(&pdev->dev,
> > +			 "LPC memory range 0x%llx-0x%llx is not fully
> > addressable",
> > +			 base_addr, base_addr + size - 1);
> > +		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;
> > +	struct pci_dn *pdn = pci_get_pdn(pdev);
> > +	u32 bdfn;
> > +	int rc;
> > +
> > +	bdfn = (pdn->busno << 8) | pdn->devfn;
> > +	rc = opal_npu_mem_release(phb->opal_id, bdfn);
> > +	WARN_ON(rc);
> 
> Same comments as above.
> 
>    Fred
> 
> 
> 
> > +}
> > +EXPORT_SYMBOL_GPL(pnv_ocxl_platform_lpc_release);
> > +
> > +
> >   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