Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On 24/07/15 11:34, David Vrabel wrote:
> On 24/07/15 10:51, Julien Grall wrote:
>> On 24/07/15 10:48, David Vrabel wrote:
>>> On 24/07/15 10:39, Julien Grall wrote:
Hi David,
On 24/07/15 10:28, David Vrabel wrote:
> On 09/07/15 21:42, 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.
>
> I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen
> front/back drivers never deal with PFNs only GFNs.
What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my
series have them.
>>>
>>> I suggesting that you introduce these.
>>
>> It's still not clear to me what you are suggesting here... Do you
>> suggest to rename xen_pfn_to_page and xen_page_to_pfn by xen_gfn_to_page
>> and xen_page_to_gfn?
>
> Effectively, yes but it would be better to think that:
>
> PFNs index guest-sized pages (which may be 64 KiB).
>
> GFNs index Xen-sized pages (which is always 4 KiB).
If I'm understanding correctly you mean:
#define xen_page_to_gfn(page) \
((page_to_pfn(page) << PAGE_SHIFT) >> XEN_PAGE_SHIFT))
static page_to_mfn(struct page *page)
{
return pfn_to_mfn(xen_page_to_gfn(page));
}
Although in some place you are suggesting to use:
xen_page_to_gfn(virt_to_page(info->intf)) (see patch #11) where it
suggests to rename page_to_mfn in xen_page_to_gfn.
I think it would make more sense to use the latter one. We would also
need to name to describe a PFN (pseudo-physical frame number based on
xen/include/xen/mm.h) but with 4K granularity and not the Linux granularity.
It's useful to have it in some place in order to iter on the 4K pfn (see
gnttab_foreach_grant and xen_apply_to_page). Maybe xpfn for Xen
pseudo-physical frame number?
I will preprend some patches into this serie to rename the function with
their correct naming.
I have in mind pfn_to_mfn which should be name into pfn_to_gfn given the
usage. Similarly, this function is mis-used on ARM because the function
may return an MFN where we expect a GFN.
Regards,
--
Julien Grall
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Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On Fri, 2015-07-24 at 11:34 +0100, David Vrabel wrote: > it would be better to think that: > > PFNs index guest-sized pages (which may be 64 KiB). > > GFNs index Xen-sized pages (which is always 4 KiB). This concept could be usefully added to the comment in xen/include/xen/mm.h IMHO. > > David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On 24/07/15 10:51, Julien Grall wrote: > On 24/07/15 10:48, David Vrabel wrote: >> On 24/07/15 10:39, Julien Grall wrote: >>> Hi David, >>> >>> On 24/07/15 10:28, David Vrabel wrote: On 09/07/15 21:42, 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. I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen front/back drivers never deal with PFNs only GFNs. >>> >>> What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my >>> series have them. >> >> I suggesting that you introduce these. > > It's still not clear to me what you are suggesting here... Do you > suggest to rename xen_pfn_to_page and xen_page_to_pfn by xen_gfn_to_page > and xen_page_to_gfn? Effectively, yes but it would be better to think that: PFNs index guest-sized pages (which may be 64 KiB). GFNs index Xen-sized pages (which is always 4 KiB). David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On 24/07/15 10:48, David Vrabel wrote: > On 24/07/15 10:39, Julien Grall wrote: >> Hi David, >> >> On 24/07/15 10:28, David Vrabel wrote: >>> On 09/07/15 21:42, 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. >>> >>> I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen >>> front/back drivers never deal with PFNs only GFNs. >> >> What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my >> series have them. > > I suggesting that you introduce these. It's still not clear to me what you are suggesting here... Do you suggest to rename xen_pfn_to_page and xen_page_to_pfn by xen_gfn_to_page and xen_page_to_gfn? Regards, -- Julien Grall -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On 24/07/15 10:39, Julien Grall wrote: > Hi David, > > On 24/07/15 10:28, David Vrabel wrote: >> On 09/07/15 21:42, 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. >> >> I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen >> front/back drivers never deal with PFNs only GFNs. > > What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my > series have them. I suggesting that you introduce these. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
Hi David, On 24/07/15 10:28, David Vrabel wrote: > On 09/07/15 21:42, 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. > > I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen > front/back drivers never deal with PFNs only GFNs. What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my series have them. Regards, -- Julien Grall -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On 09/07/15 21:42, 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. I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen front/back drivers never deal with PFNs only GFNs. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
Hi David, On 24/07/15 10:28, David Vrabel wrote: On 09/07/15 21:42, 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 julien.gr...@citrix.com Cc: Konrad Rzeszutek Wilk konrad.w...@oracle.com Cc: Boris Ostrovsky boris.ostrov...@oracle.com Cc: David Vrabel david.vra...@citrix.com --- I'm wondering if we should drop page_to_pfn has the macro will likely misuse when Linux is using 64KB page granularity. I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen front/back drivers never deal with PFNs only GFNs. What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my series have them. Regards, -- Julien Grall -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On 24/07/15 10:48, David Vrabel wrote: On 24/07/15 10:39, Julien Grall wrote: Hi David, On 24/07/15 10:28, David Vrabel wrote: On 09/07/15 21:42, 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 julien.gr...@citrix.com Cc: Konrad Rzeszutek Wilk konrad.w...@oracle.com Cc: Boris Ostrovsky boris.ostrov...@oracle.com Cc: David Vrabel david.vra...@citrix.com --- I'm wondering if we should drop page_to_pfn has the macro will likely misuse when Linux is using 64KB page granularity. I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen front/back drivers never deal with PFNs only GFNs. What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my series have them. I suggesting that you introduce these. It's still not clear to me what you are suggesting here... Do you suggest to rename xen_pfn_to_page and xen_page_to_pfn by xen_gfn_to_page and xen_page_to_gfn? Regards, -- Julien Grall -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On 09/07/15 21:42, 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 julien.gr...@citrix.com Cc: Konrad Rzeszutek Wilk konrad.w...@oracle.com Cc: Boris Ostrovsky boris.ostrov...@oracle.com Cc: David Vrabel david.vra...@citrix.com --- I'm wondering if we should drop page_to_pfn has the macro will likely misuse when Linux is using 64KB page granularity. I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen front/back drivers never deal with PFNs only GFNs. David -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On 24/07/15 10:39, Julien Grall wrote: Hi David, On 24/07/15 10:28, David Vrabel wrote: On 09/07/15 21:42, 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 julien.gr...@citrix.com Cc: Konrad Rzeszutek Wilk konrad.w...@oracle.com Cc: Boris Ostrovsky boris.ostrov...@oracle.com Cc: David Vrabel david.vra...@citrix.com --- I'm wondering if we should drop page_to_pfn has the macro will likely misuse when Linux is using 64KB page granularity. I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen front/back drivers never deal with PFNs only GFNs. What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my series have them. I suggesting that you introduce these. David -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On 24/07/15 11:34, David Vrabel wrote:
On 24/07/15 10:51, Julien Grall wrote:
On 24/07/15 10:48, David Vrabel wrote:
On 24/07/15 10:39, Julien Grall wrote:
Hi David,
On 24/07/15 10:28, David Vrabel wrote:
On 09/07/15 21:42, 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 julien.gr...@citrix.com
Cc: Konrad Rzeszutek Wilk konrad.w...@oracle.com
Cc: Boris Ostrovsky boris.ostrov...@oracle.com
Cc: David Vrabel david.vra...@citrix.com
---
I'm wondering if we should drop page_to_pfn has the macro will likely
misuse when Linux is using 64KB page granularity.
I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen
front/back drivers never deal with PFNs only GFNs.
What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my
series have them.
I suggesting that you introduce these.
It's still not clear to me what you are suggesting here... Do you
suggest to rename xen_pfn_to_page and xen_page_to_pfn by xen_gfn_to_page
and xen_page_to_gfn?
Effectively, yes but it would be better to think that:
PFNs index guest-sized pages (which may be 64 KiB).
GFNs index Xen-sized pages (which is always 4 KiB).
If I'm understanding correctly you mean:
#define xen_page_to_gfn(page) \
((page_to_pfn(page) PAGE_SHIFT) XEN_PAGE_SHIFT))
static page_to_mfn(struct page *page)
{
return pfn_to_mfn(xen_page_to_gfn(page));
}
Although in some place you are suggesting to use:
xen_page_to_gfn(virt_to_page(info-intf)) (see patch #11) where it
suggests to rename page_to_mfn in xen_page_to_gfn.
I think it would make more sense to use the latter one. We would also
need to name to describe a PFN (pseudo-physical frame number based on
xen/include/xen/mm.h) but with 4K granularity and not the Linux granularity.
It's useful to have it in some place in order to iter on the 4K pfn (see
gnttab_foreach_grant and xen_apply_to_page). Maybe xpfn for Xen
pseudo-physical frame number?
I will preprend some patches into this serie to rename the function with
their correct naming.
I have in mind pfn_to_mfn which should be name into pfn_to_gfn given the
usage. Similarly, this function is mis-used on ARM because the function
may return an MFN where we expect a GFN.
Regards,
--
Julien Grall
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On Fri, 2015-07-24 at 11:34 +0100, David Vrabel wrote: it would be better to think that: PFNs index guest-sized pages (which may be 64 KiB). GFNs index Xen-sized pages (which is always 4 KiB). This concept could be usefully added to the comment in xen/include/xen/mm.h IMHO. David -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Xen-devel] [PATCH v2 01/20] xen: Add Xen specific page definition
On 24/07/15 10:51, Julien Grall wrote: On 24/07/15 10:48, David Vrabel wrote: On 24/07/15 10:39, Julien Grall wrote: Hi David, On 24/07/15 10:28, David Vrabel wrote: On 09/07/15 21:42, 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 julien.gr...@citrix.com Cc: Konrad Rzeszutek Wilk konrad.w...@oracle.com Cc: Boris Ostrovsky boris.ostrov...@oracle.com Cc: David Vrabel david.vra...@citrix.com --- I'm wondering if we should drop page_to_pfn has the macro will likely misuse when Linux is using 64KB page granularity. I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen front/back drivers never deal with PFNs only GFNs. What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my series have them. I suggesting that you introduce these. It's still not clear to me what you are suggesting here... Do you suggest to rename xen_pfn_to_page and xen_page_to_pfn by xen_gfn_to_page and xen_page_to_gfn? Effectively, yes but it would be better to think that: PFNs index guest-sized pages (which may be 64 KiB). GFNs index Xen-sized pages (which is always 4 KiB). David -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
