| Message ID | 1436474552-31789-5-git-send-email-julien.grall@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 9 Jul 2015, Julien Grall wrote: > Many PV drivers contain the idiom: > > pfn = page_to_mfn(...) /* Or similar */ > gnttab_grant_foreign_access_ref > > Replace it by a new helper. Note that when Linux is using a different > page granularity than Xen, the helper only gives access to the first 4KB > grant. > > This is useful where drivers are allocating a full Linux page for each > grant. > > Also include xen/interface/grant_table.h rather than xen/grant_table.h in > asm/page.h for x86 to fix a compilation issue [1]. Only the former is > useful in order to get the structure definition. > > [1] Interpendency between asm/page.h and xen/grant_table.h which result > to page_mfn not being defined when necessary. > > Signed-off-by: Julien Grall <julien.grall@linaro.org> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Cc: David Vrabel <david.vrabel@citrix.com> > --- > Changes in v2: > - Patch added > --- > arch/x86/include/asm/xen/page.h | 2 +- > include/xen/grant_table.h | 9 +++++++++ > 2 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h > index c44a5d5..fb2e037 100644 > --- a/arch/x86/include/asm/xen/page.h > +++ b/arch/x86/include/asm/xen/page.h > @@ -12,7 +12,7 @@ > #include <asm/pgtable.h> > > #include <xen/interface/xen.h> > -#include <xen/grant_table.h> > +#include <xen/interface/grant_table.h> > #include <xen/features.h> > > /* Xen machine address */ > diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h > index 6f77378..6a1ef86 100644 > --- a/include/xen/grant_table.h > +++ b/include/xen/grant_table.h > @@ -131,6 +131,15 @@ void gnttab_cancel_free_callback(struct gnttab_free_callback *callback); > void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid, > unsigned long frame, int readonly); > > +/* Give access to the first 4K of the page */ > +static inline void gnttab_page_grant_foreign_access_ref( > + grant_ref_t ref, domid_t domid, > + struct page *page, int readonly) > +{ I like this. I think it might make sense to call it gnttab_page_grant_foreign_access_ref_one to make clear that it is only granting the first 4K. In the future we could introduce a new function, called gnttab_page_grant_foreign_access_ref, that grants all 4K in the page. In any case Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > + gnttab_grant_foreign_access_ref(ref, domid, page_to_mfn(page), > + readonly); > +} > + > void gnttab_grant_foreign_transfer_ref(grant_ref_t, domid_t domid, > unsigned long pfn); > > -- > 2.1.4 >
Hi Stefano, On 16/07/2015 16:05, Stefano Stabellini wrote: > I like this. I think it might make sense to call it > gnttab_page_grant_foreign_access_ref_one to make clear that it is only > granting the first 4K. Will do. > In the future we could introduce a new function, called > gnttab_page_grant_foreign_access_ref, that grants all 4K in the page. Unless having a different prototype it won't be possible to do it. This is because one ref = one grant. We would need a list of grant. > In any case > > Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Thank you,
On 09/07/15 21:42, Julien Grall wrote: > Many PV drivers contain the idiom: > > pfn = page_to_mfn(...) /* Or similar */ > gnttab_grant_foreign_access_ref > > Replace it by a new helper. Note that when Linux is using a different > page granularity than Xen, the helper only gives access to the first 4KB > grant. > > This is useful where drivers are allocating a full Linux page for each > grant. > > Also include xen/interface/grant_table.h rather than xen/grant_table.h in > asm/page.h for x86 to fix a compilation issue [1]. Only the former is > useful in order to get the structure definition. > > [1] Interpendency between asm/page.h and xen/grant_table.h which result > to page_mfn not being defined when necessary. [...] > --- a/include/xen/grant_table.h > +++ b/include/xen/grant_table.h > @@ -131,6 +131,15 @@ void gnttab_cancel_free_callback(struct gnttab_free_callback *callback); > void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid, > unsigned long frame, int readonly); > > +/* Give access to the first 4K of the page */ > +static inline void gnttab_page_grant_foreign_access_ref( > + grant_ref_t ref, domid_t domid, > + struct page *page, int readonly) > +{ > + gnttab_grant_foreign_access_ref(ref, domid, page_to_mfn(page), Obviously this would use the new xen_page_to_gfn() macro here. Otherwise, Reviewed-by: David Vrabel <david.vrabel@citrix.com> David
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h index c44a5d5..fb2e037 100644 --- a/arch/x86/include/asm/xen/page.h +++ b/arch/x86/include/asm/xen/page.h @@ -12,7 +12,7 @@ #include <asm/pgtable.h> #include <xen/interface/xen.h> -#include <xen/grant_table.h> +#include <xen/interface/grant_table.h> #include <xen/features.h> /* Xen machine address */ diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h index 6f77378..6a1ef86 100644 --- a/include/xen/grant_table.h +++ b/include/xen/grant_table.h @@ -131,6 +131,15 @@ void gnttab_cancel_free_callback(struct gnttab_free_callback *callback); void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid, unsigned long frame, int readonly); +/* Give access to the first 4K of the page */ +static inline void gnttab_page_grant_foreign_access_ref( + grant_ref_t ref, domid_t domid, + struct page *page, int readonly) +{ + gnttab_grant_foreign_access_ref(ref, domid, page_to_mfn(page), + readonly); +} + void gnttab_grant_foreign_transfer_ref(grant_ref_t, domid_t domid, unsigned long pfn);
Many PV drivers contain the idiom: pfn = page_to_mfn(...) /* Or similar */ gnttab_grant_foreign_access_ref Replace it by a new helper. Note that when Linux is using a different page granularity than Xen, the helper only gives access to the first 4KB grant. This is useful where drivers are allocating a full Linux page for each grant. Also include xen/interface/grant_table.h rather than xen/grant_table.h in asm/page.h for x86 to fix a compilation issue [1]. Only the former is useful in order to get the structure definition. [1] Interpendency between asm/page.h and xen/grant_table.h which result to page_mfn not being defined when necessary. Signed-off-by: Julien Grall <julien.grall@linaro.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> --- Changes in v2: - Patch added --- arch/x86/include/asm/xen/page.h | 2 +- include/xen/grant_table.h | 9 +++++++++ 2 files changed, 10 insertions(+), 1 deletion(-)