From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefano Stabellini Subject: Re: [PATCH v2 01/20] xen: Add Xen specific page definition Date: Thu, 16 Jul 2015 15:19:31 +0100 Message-ID: References: <1436474552-31789-1-git-send-email-julien.grall@citrix.com> <1436474552-31789-2-git-send-email-julien.grall@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1ZFk1y-00054n-J8 for xen-devel@lists.xenproject.org; Thu, 16 Jul 2015 14:20:58 +0000 In-Reply-To: <1436474552-31789-2-git-send-email-julien.grall@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Julien Grall Cc: ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com, linux-kernel@vger.kernel.org, David Vrabel , xen-devel@lists.xenproject.org, Boris Ostrovsky , linux-arm-kernel@lists.infradead.org List-Id: xen-devel@lists.xenproject.org On Thu, 9 Jul 2015, Julien Grall wrote: > The Xen hypercall interface is always using 4K page granularity on ARM > and x86 architecture. > > With the incoming support of 64K page granularity for ARM64 guest, it > won't be possible to re-use the Linux page definition in Xen drivers. > > Introduce Xen page definition helpers based on the Linux page > definition. They have exactly the same name but prefixed with > XEN_/xen_ prefix. > > Also modify page_to_pfn to use new Xen page definition. > > Signed-off-by: Julien Grall > Cc: Konrad Rzeszutek Wilk > Cc: Boris Ostrovsky > Cc: David Vrabel > --- > I'm wondering if we should drop page_to_pfn has the macro will likely > misuse when Linux is using 64KB page granularity. > > Changes in v2: > - Add XEN_PFN_UP > - Add a comment describing the behavior of page_to_pfn > --- > include/xen/page.h | 21 ++++++++++++++++++++- > 1 file changed, 20 insertions(+), 1 deletion(-) > > diff --git a/include/xen/page.h b/include/xen/page.h > index c5ed20b..8ebd37b 100644 > --- a/include/xen/page.h > +++ b/include/xen/page.h > @@ -1,11 +1,30 @@ > #ifndef _XEN_PAGE_H > #define _XEN_PAGE_H > > +#include > + > +/* The hypercall interface supports only 4KB page */ > +#define XEN_PAGE_SHIFT 12 > +#define XEN_PAGE_SIZE (_AC(1,UL) << XEN_PAGE_SHIFT) > +#define XEN_PAGE_MASK (~(XEN_PAGE_SIZE-1)) > +#define xen_offset_in_page(p) ((unsigned long)(p) & ~XEN_PAGE_MASK) > +#define xen_pfn_to_page(pfn) \ I think it would be clearer if you called the parameter "xen_pfn" instead of "pfn". > + ((pfn_to_page(((unsigned long)(pfn) << XEN_PAGE_SHIFT) >> PAGE_SHIFT))) > +#define xen_page_to_pfn(page) \ > + (((page_to_pfn(page)) << PAGE_SHIFT) >> XEN_PAGE_SHIFT) It would be nice to have a comment: /* assume PAGE_SIZE is a multiple of XEN_PAGE_SIZE */ > +#define XEN_PFN_PER_PAGE (PAGE_SIZE / XEN_PAGE_SIZE) > + > +#define XEN_PFN_DOWN(x) ((x) >> XEN_PAGE_SHIFT) > +#define XEN_PFN_UP(x) (((x) + XEN_PAGE_SIZE-1) >> XEN_PAGE_SHIFT) > +#define XEN_PFN_PHYS(x) ((phys_addr_t)(x) << XEN_PAGE_SHIFT) > + > #include > > +/* Return the MFN associated to the first 4KB of the page */ > static inline unsigned long page_to_mfn(struct page *page) > { > - return pfn_to_mfn(page_to_pfn(page)); > + return pfn_to_mfn(xen_page_to_pfn(page)); > } > > struct xen_memory_region { Aside from the two minor suggestions: Reviewed-by: Stefano Stabellini