On Wed, Aug 05, 2015 at 11:08:55AM +0100, Stefano Stabellini wrote:

On Tue, 4 Aug 2015, Julien Grall wrote:

quoted

Based on include/xen/mm.h [1], Linux is mistakenly using MFN when GFN
is meant, I suspect this is because the first support for Xen was for
PV. This resulted in some misimplementation of helpers on ARM and
confused developers about the expected behavior.

For instance, with pfn_to_mfn, we expect to get an MFN based on the name.
Although, if we look at the implementation on x86, it's returning a GFN.

For clarity and avoid new confusion, replace any reference to mfn with
gfn in any helpers used by PV drivers. The x86 code will still keep some
reference of pfn_to_mfn but exclusively for PV (a BUG_ON has been added
to ensure this). No changes as been made in the hypercall field, even
though they may be invalid, in order to keep the same as the defintion
in xen repo.

Take also the opportunity to simplify simple construction such
as pfn_to_mfn(page_to_pfn(page)) into page_to_gfn. More complex clean up
will come in follow-up patches.

[1] http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;hç58ed14f390342513405dd766e874934573e6cb

Signed-off-by: Julien Grall <redacted>
Cc: Stefano Stabellini <redacted>
Cc: Russell King <redacted>
Cc: Konrad Rzeszutek Wilk <redacted>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <redacted>
Cc: Thomas Gleixner <redacted>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Ian Campbell <redacted>
Cc: Wei Liu <redacted>
Cc: Juergen Gross <jgross@suse.com>
Cc: "James E.J. Bottomley" <redacted>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <redacted>
Cc: Jean-Christophe Plagniol-Villard <redacted>
Cc: Tomi Valkeinen <redacted>
Cc: linux-input@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-fbdev@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org

Aside from the x86 bits:

Reviewed-by: Stefano Stabellini <redacted>

Not really important, but just in case anyone waits for my ack on input
bits:

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Thanks.

-- 
Dmitry