linux-kernel - Re: [PATCH] arm/xen: Remove definiition of virt_to

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Message-ID: <alpine.DEB.2.02.1405071234010.14596@kaball.uk.xensource.com>
Date:	Wed, 7 May 2014 12:41:56 +0100
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Stefano Stabellini <stefano.stabellini@...citrix.com>
CC:	David Vrabel <david.vrabel@...rix.com>,
	Julien Grall <julien.grall@...aro.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <xen-devel@...ts.xenproject.org>,
	Ian Campbell <ian.campbell@...rix.com>,
	<konrad.wilk@...cle.com>, Catalin Marinas <catalin.marinas@....com>
Subject: Re: [PATCH] arm/xen: Remove definiition of virt_to_pfn in
 asm/xen/page.h

On Fri, 25 Apr 2014, Stefano Stabellini wrote:
> On Thu, 24 Apr 2014, David Vrabel wrote:
> > On 24/04/14 13:49, Julien Grall wrote:
> > > Hi David,
> > > 
> > > On 04/24/2014 01:22 PM, David Vrabel wrote:
> > >> On 18/04/14 16:54, Julien Grall wrote:
> > >>> virt_to_pfn has been defined in asm/memory.h by the commit e26a9e0 "ARM: Better
> > >>> virt_to_page() handling"
> > >>>
> > >>> This will result of a compilation warning when CONFIG_XEN is enabled.
> > >>>
> > >>> arch/arm/include/asm/xen/page.h:80:0: warning: "virt_to_pfn" redefined [enabled by default]
> > >>>  #define virt_to_pfn(v)          (PFN_DOWN(__pa(v)))
> > >>>  ^
> > >>> In file included from arch/arm/include/asm/page.h:163:0,
> > >>>                  from arch/arm/include/asm/xen/page.h:4,
> > >>>                  from include/xen/page.h:4,
> > >>>                  from arch/arm/xen/grant-table.c:33:
> > >>>
> > >>> The definition in memory.h is nearly the same (it directly expand PFN_DOWN),
> > >>> so we can safely drop virt_to_pfn in xen include.
> > >>
> > >>
> > >> This breaks the arm build for me.
> > >>
> > >> /local/davidvr/work/k.org/tip/drivers/block/xen-blkfront.c: In function
> > >> ‘setup_blkring’:
> > >> /local/davidvr/work/k.org/tip/drivers/block/xen-blkfront.c:1236:2:
> > >> error: implicit declaration of function ‘virt_to_pfn’
> > >> [-Werror=implicit-function-declaration]
> > >>   err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
> > >>   ^
> > > 
> > > I don't have any issue to build the following branch with this patch on:
> > > 	- v3.15-rc2
> > > 	- xentip master
> > > 	- xentip for-linus-3.16
> > 
> > Applied to devel/for-linus-3.16.
> > 
> > If something else turns up for 3.15 (and I remember) I'll take it for
> > 3.15 instead.
> 
> David,
> thank you very much for taking the patch in my absence.
> 
> Considering that the problem is affecting everybody enabling CONFIG_XEN
> on ARM on v3.15, I don't think we can wait for the next merge window to
> send this fix upstream.
> Too many warnings for too many people.

Unfortunately this commit breaks arm64 compilation, as virt_to_pfn has
not been introduced to arm64/include/asm/memory.h.
Has the patch been sent upstream yet?

We need this additional change for arm64:


diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index e94f945..993bce5 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -138,6 +138,7 @@ static inline void *phys_to_virt(phys_addr_t x)
 #define __pa(x)			__virt_to_phys((unsigned long)(x))
 #define __va(x)			((void *)__phys_to_virt((phys_addr_t)(x)))
 #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
+#define virt_to_pfn(x)      __phys_to_pfn(__virt_to_phys(x))
 
 /*
  *  virt_to_page(k)	convert a _valid_ virtual address to struct page *