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Date: Thu, 20 Dec 2018 15:53:04 +0100
From: Greg Kurz <groug@kaod.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, stable@vger.kernel.org,
        Christophe Lombard <clombard@linux.vnet.ibm.com>,
        Frederic Barrat <fbarrat@linux.vnet.ibm.com>,
        Vaibhav Jain <vaibhav@linux.vnet.ibm.com>,
        Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Subject: Re: [PATCH v2] ocxl: Fix endiannes bug in read_afu_name()
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On Wed, 12 Dec 2018 13:26:10 +1100
Andrew Donnellan <andrew.donnellan@au1.ibm.com> wrote:

> On 12/12/18 4:58 am, Greg Kurz wrote:
> > The AFU Descriptor Template in the PCI config space has a Name Space
> > field which is a 24 Byte ASCII character string of descriptive name
> > space for the AFU. The OCXL driver read the string four characters at
> > a time with pci_read_config_dword().
> > 
> > This optimization is valid on a little-endian system since this is PCI,
> > but a big-endian system ends up with each subset of four characters in
> > reverse order.
> > 
> > This could be fixed by switching to read characters one by one. Another
> > option is to swap the bytes if we're big-endian.
> > 
> > Go for the latter with le32_to_cpu().
> > 
> > Cc: stable@vger.kernel.org      # v4.16
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> > Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>  
> 
> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
> 

Friendly ping before Xmas break :)

> > ---
> > v2: - silence sparse with (__force __le32) cast
> >      - new changelog
> > ---
> >   drivers/misc/ocxl/config.c |    2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/misc/ocxl/config.c b/drivers/misc/ocxl/config.c
> > index 57a6bb1fd3c9..8f2c5d8bd2ee 100644
> > --- a/drivers/misc/ocxl/config.c
> > +++ b/drivers/misc/ocxl/config.c
> > @@ -318,7 +318,7 @@ static int read_afu_name(struct pci_dev *dev, struct ocxl_fn_config *fn,
> >   		if (rc)
> >   			return rc;
> >   		ptr = (u32 *) &afu->name[i];
> > -		*ptr = val;
> > +		*ptr = le32_to_cpu((__force __le32) val);
> >   	}
> >   	afu->name[OCXL_AFU_NAME_SZ - 1] = '\0'; /* play safe */
> >   	return 0;
> >   
>