Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933666AbbHJKqV (ORCPT ); Mon, 10 Aug 2015 06:46:21 -0400 Received: from smtp.citrix.com ([66.165.176.89]:48331 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933693AbbHJKqR (ORCPT ); Mon, 10 Aug 2015 06:46:17 -0400 X-IronPort-AV: E=Sophos;i="5.15,644,1432598400"; d="scan'208";a="289598067" Date: Mon, 10 Aug 2015 11:44:48 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Julien Grall CC: , , , , , Konrad Rzeszutek Wilk , Boris Ostrovsky , "David Vrabel" , Thomas Gleixner , "Ingo Molnar" , "H. Peter Anvin" , Subject: Re: [PATCH v3 04/20] xen/grant: Introduce helpers to split a page into grant In-Reply-To: <1438966019-19322-5-git-send-email-julien.grall@citrix.com> Message-ID: References: <1438966019-19322-1-git-send-email-julien.grall@citrix.com> <1438966019-19322-5-git-send-email-julien.grall@citrix.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5953 Lines: 174 On Fri, 7 Aug 2015, Julien Grall wrote: > Currently, a grant is always based on the Xen page granularity (i.e > 4KB). When Linux is using a different page granularity, a single page > will be split between multiple grants. > > The new helpers will be in charge to split the Linux page into grants and ^ of splitting > call a function given by the caller on each grant. > > Also provide an helper to count the number of grants within a given > contiguous region. > > Note that the x86/include/asm/xen/page.h is now including > xen/interface/grant_table.h rather than xen/grant_table.h. It's > necessary because xen/grant_table.h depends on asm/xen/page.h and will > break the compilation. Furthermore, only definition in > interface/grant_table.h was required. ^ is > Signed-off-by: Julien Grall Reviewed-by: Stefano Stabellini > --- > Cc: Konrad Rzeszutek Wilk > Cc: Boris Ostrovsky > Cc: David Vrabel > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: "H. Peter Anvin" > Cc: x86@kernel.org > > Changes in v3: > - Fix error reported by checkpatch.pl > - Typoes > - s/pfn/xen_pfn/ in gnttab_foreach_grant > - Drop the possibility to use less data. The complexity is moved > in netback which is the only user > - Rename gnttab_foreach_grant into gnttab_foreach_grant_in_range > - s/offset/start/ in gnttab_count_grant and update the > description of the parameter > - s/mfn/gfn base on the new terminologies > - Add EXPORT_SYMBOL_GPL for gnttab_foreach_grant_in_range > - Use xen_offset_in_page and XEN_PFN_DOWN whenever it's possible > - Fix compilation on x86. > > Changes in v2: > - Patch added > --- > arch/x86/include/asm/xen/page.h | 2 +- > drivers/xen/grant-table.c | 26 +++++++++++++++++++++++++ > include/xen/grant_table.h | 42 +++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 69 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h > index 0b762f6..501479e 100644 > --- a/arch/x86/include/asm/xen/page.h > +++ b/arch/x86/include/asm/xen/page.h > @@ -12,7 +12,7 @@ > #include > > #include > -#include > +#include > #include > > /* Xen machine address */ > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c > index 62f591f..94ae0fd 100644 > --- a/drivers/xen/grant-table.c > +++ b/drivers/xen/grant-table.c > @@ -776,6 +776,32 @@ void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count) > } > EXPORT_SYMBOL_GPL(gnttab_batch_copy); > > +void gnttab_foreach_grant_in_range(struct page *page, > + unsigned int offset, > + unsigned int len, > + xen_grant_fn_t fn, > + void *data) > +{ > + unsigned int goffset; > + unsigned int glen; > + unsigned long xen_pfn; > + > + len = min_t(unsigned int, PAGE_SIZE - offset, len); > + goffset = xen_offset_in_page(offset); > + > + xen_pfn = xen_page_to_pfn(page) + XEN_PFN_DOWN(offset); > + > + while (len) { > + glen = min_t(unsigned int, XEN_PAGE_SIZE - goffset, len); > + fn(pfn_to_gfn(xen_pfn), goffset, glen, data); > + > + goffset = 0; > + xen_pfn++; > + len -= glen; > + } > +} > +EXPORT_SYMBOL_GPL(gnttab_foreach_grant_in_range); > + > int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > struct gnttab_map_grant_ref *kmap_ops, > struct page **pages, unsigned int count) > diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h > index 4478f4b..2a8ebe8 100644 > --- a/include/xen/grant_table.h > +++ b/include/xen/grant_table.h > @@ -45,8 +45,10 @@ > #include > > #include > +#include > #include > #include > +#include > > #define GNTTAB_RESERVED_XENSTORE 1 > > @@ -224,4 +226,44 @@ static inline struct xen_page_foreign *xen_page_foreign(struct page *page) > #endif > } > > +/* Split Linux page in chunk of the size of the grant and call fn > + * > + * Parameters of fn: > + * gfn: guest frame number > + * offset: offset in the grant > + * len: length of the data in the grant. > + * data: internal information > + */ > +typedef void (*xen_grant_fn_t)(unsigned long gfn, unsigned int offset, > + unsigned int len, void *data); > + > +void gnttab_foreach_grant_in_range(struct page *page, > + unsigned int offset, > + unsigned int len, > + xen_grant_fn_t fn, > + void *data); > + > +/* Helper to get to call fn only on the first "grant chunk" */ > +static inline void gnttab_one_grant(struct page *page, unsigned int offset, > + unsigned len, xen_grant_fn_t fn, > + void *data) > +{ > + /* The first request is limited to the size of one grant */ > + len = min_t(unsigned int, XEN_PAGE_SIZE - (offset & ~XEN_PAGE_MASK), > + len); > + > + gnttab_foreach_grant_in_range(page, offset, len, fn, data); > +} > + > +/* Get the number of grant in a specified region > + * > + * start: Offset from the beginning of the first page > + * len: total length of data (can cross multiple page) > + */ > +static inline unsigned int gnttab_count_grant(unsigned int start, > + unsigned int len) > +{ > + return XEN_PFN_UP(xen_offset_in_page(start) + len); > +} > + > #endif /* __ASM_GNTTAB_H__ */ > -- > 2.1.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/