sources of freebsd with xen-4.2 kernel updates

sources of freebsd with xen-4.2 kernel updates

[Igor Kozhukhov]

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Hi All,

could you please help me try to find sources of FreeBSD with xen-4.x kernel updates ?
i'm interested in grant-table realization with v1 and v2.

--
Best regards,
Igor Kozhukhov





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Re: sources of freebsd with xen-4.2 kernel updates

[Roger Pau Monné]

On 29/12/13 18:54, Igor Kozhukhov wrote:
> Hi All,
> 
> could you please help me try to find sources of FreeBSD with xen-4.x
> kernel updates ?
> i'm interested in grant-table realization with v1 and v2.

Hello,

You can find FreeBSD grant table related code here:

http://svnweb.freebsd.org/base/head/sys/xen/gnttab.c?view=co

It contains support for both HVM and PV guests, but only version 1.

Roger.

Re: sources of freebsd with xen-4.2 kernel updates

[Igor Kozhukhov]

Hi Roger,

thanks for the link.
I have the same/(similar the same) implementation on illumos(OpenSolaris).

do you have plans for grant table v1 & v2 implementation on FreeBSD ?

--
Best regards,
Igor Kozhukhov




On Dec 30, 2013, at 12:10 PM, Roger Pau Monné wrote:

> On 29/12/13 18:54, Igor Kozhukhov wrote:
>> Hi All,
>> 
>> could you please help me try to find sources of FreeBSD with xen-4.x
>> kernel updates ?
>> i'm interested in grant-table realization with v1 and v2.
> 
> Hello,
> 
> You can find FreeBSD grant table related code here:
> 
> http://svnweb.freebsd.org/base/head/sys/xen/gnttab.c?view=co
> 
> It contains support for both HVM and PV guests, but only version 1.
> 
> Roger.
> 

Re: sources of freebsd with xen-4.2 kernel updates

[Roger Pau Monné]

On 30/12/13 11:57, Igor Kozhukhov wrote:
> Hi Roger,
> 
> thanks for the link.
> I have the same/(similar the same) implementation on illumos(OpenSolaris).
> 
> do you have plans for grant table v1 & v2 implementation on FreeBSD ?

Grant table v1 is the current implementation, and I don't have plans
currently to add support for v2 (cannot speak of others though).

Linux has v2 implemented, but AFAIK there's no user of the new features
introduced by v2. Right now with v2 you just end up with less grants,
because v2 grants metadata use twice as much memory as v1 grants, and
the number of grant frames is limited by the hypervisor.

Roger.

Re: sources of freebsd with xen-4.2 kernel updates

[Igor Kozhukhov]

On Dec 30, 2013, at 3:25 PM, Roger Pau Monné wrote:

> On 30/12/13 11:57, Igor Kozhukhov wrote:
>> Hi Roger,
>> 
>> thanks for the link.
>> I have the same/(similar the same) implementation on illumos(OpenSolaris).
>> 
>> do you have plans for grant table v1 & v2 implementation on FreeBSD ?
> 
> Grant table v1 is the current implementation, and I don't have plans
> currently to add support for v2 (cannot speak of others though).
> 
> Linux has v2 implemented, but AFAIK there's no user of the new features
> introduced by v2. Right now with v2 you just end up with less grants,
> because v2 grants metadata use twice as much memory as v1 grants, and
> the number of grant frames is limited by the hypervisor.
> 
Thanks for your info.

Could you please let me know - can we use v1 for PV and HVM guests ?
I looked v2 implementation on Linux and found that v1 is using for HVM, and v2 for PV - but maybe i'm wrong.

-Igor

> Roger.
> 

Re: sources of freebsd with xen-4.2 kernel updates

[Wei Liu]

On Mon, Dec 30, 2013 at 04:18:28PM +0400, Igor Kozhukhov wrote:
> 
> On Dec 30, 2013, at 3:25 PM, Roger Pau Monné wrote:
> 
> > On 30/12/13 11:57, Igor Kozhukhov wrote:
> >> Hi Roger,
> >> 
> >> thanks for the link.
> >> I have the same/(similar the same) implementation on illumos(OpenSolaris).
> >> 
> >> do you have plans for grant table v1 & v2 implementation on FreeBSD ?
> > 
> > Grant table v1 is the current implementation, and I don't have plans
> > currently to add support for v2 (cannot speak of others though).
> > 
> > Linux has v2 implemented, but AFAIK there's no user of the new features
> > introduced by v2. Right now with v2 you just end up with less grants,
> > because v2 grants metadata use twice as much memory as v1 grants, and
> > the number of grant frames is limited by the hypervisor.
> > 
> Thanks for your info.
> 
> Could you please let me know - can we use v1 for PV and HVM guests ?
> I looked v2 implementation on Linux and found that v1 is using for HVM, and v2 for PV - but maybe i'm wrong.
> 

You can use V1 for all guests for sure.

My understanding is that the code in Linux's grant-table.c requests V2
form the hypervisor, but it will fall back to using V1 if V2 is not
avaiable.

Wei.

> -Igor
> 
> > Roger.
> > 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

Re: sources of freebsd with xen-4.2 kernel updates

[Roger Pau Monné]

On 30/12/13 13:42, Wei Liu wrote:
> On Mon, Dec 30, 2013 at 04:18:28PM +0400, Igor Kozhukhov wrote:
>>
>> On Dec 30, 2013, at 3:25 PM, Roger Pau Monné wrote:
>>
>>> On 30/12/13 11:57, Igor Kozhukhov wrote:
>>>> Hi Roger,
>>>>
>>>> thanks for the link.
>>>> I have the same/(similar the same) implementation on illumos(OpenSolaris).
>>>>
>>>> do you have plans for grant table v1 & v2 implementation on FreeBSD ?
>>>
>>> Grant table v1 is the current implementation, and I don't have plans
>>> currently to add support for v2 (cannot speak of others though).
>>>
>>> Linux has v2 implemented, but AFAIK there's no user of the new features
>>> introduced by v2. Right now with v2 you just end up with less grants,
>>> because v2 grants metadata use twice as much memory as v1 grants, and
>>> the number of grant frames is limited by the hypervisor.
>>>
>> Thanks for your info.
>>
>> Could you please let me know - can we use v1 for PV and HVM guests ?
>> I looked v2 implementation on Linux and found that v1 is using for HVM, and v2 for PV - but maybe i'm wrong.
>>
> 
> You can use V1 for all guests for sure.
> 
> My understanding is that the code in Linux's grant-table.c requests V2
> form the hypervisor, but it will fall back to using V1 if V2 is not
> avaiable.

Linux explicitly requests v1 when running as an HVM guest (I have no
idea why), for the rest it tries v2 first and falls back to v1 if
there's no v2 support:

http://lxr.free-electrons.com/source/drivers/xen/grant-table.c#L1116

As Wei points out, you can safely use v1 for all kind of guests, at
least on x86.

Roger.

Re: sources of freebsd with xen-4.2 kernel updates

[Konrad Rzeszutek Wilk]

On Mon, Dec 30, 2013 at 01:53:01PM +0100, Roger Pau Monné wrote:
> On 30/12/13 13:42, Wei Liu wrote:
> > On Mon, Dec 30, 2013 at 04:18:28PM +0400, Igor Kozhukhov wrote:
> >>
> >> On Dec 30, 2013, at 3:25 PM, Roger Pau Monné wrote:
> >>
> >>> On 30/12/13 11:57, Igor Kozhukhov wrote:
> >>>> Hi Roger,
> >>>>
> >>>> thanks for the link.
> >>>> I have the same/(similar the same) implementation on illumos(OpenSolaris).
> >>>>
> >>>> do you have plans for grant table v1 & v2 implementation on FreeBSD ?
> >>>
> >>> Grant table v1 is the current implementation, and I don't have plans
> >>> currently to add support for v2 (cannot speak of others though).
> >>>
> >>> Linux has v2 implemented, but AFAIK there's no user of the new features
> >>> introduced by v2. Right now with v2 you just end up with less grants,
> >>> because v2 grants metadata use twice as much memory as v1 grants, and
> >>> the number of grant frames is limited by the hypervisor.
> >>>
> >> Thanks for your info.
> >>
> >> Could you please let me know - can we use v1 for PV and HVM guests ?
> >> I looked v2 implementation on Linux and found that v1 is using for HVM, and v2 for PV - but maybe i'm wrong.
> >>
> > 
> > You can use V1 for all guests for sure.
> > 
> > My understanding is that the code in Linux's grant-table.c requests V2
> > form the hypervisor, but it will fall back to using V1 if V2 is not
> > avaiable.
> 
> Linux explicitly requests v1 when running as an HVM guest (I have no
> idea why), for the rest it tries v2 first and falls back to v1 if

B/c it did not have the code to support mapping of the status page:

commit 69e8f430e243d657c2053f097efebc2e2cd559f0
Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date:   Wed Jan 25 00:13:20 2012 -0500

    xen/granttable: Disable grant v2 for HVM domains.
    
    As proper scaffolding for supporting error status is not yet
    implemented.
    
    BUG: unable to handle kernel NULL pointer dereference at 0000000000000400
    IP: [<ffffffff81375ae9>] gnttab_end_foreign_access_ref_v2+0x29/0x40
    PGD 32aa3067 PUD 32a87067 PMD 0
    Oops: 0000 [#1] PREEMPT SMP
    CPU 0
    Modules linked in: sg sr_mod cdrom ata_generic ata_piix libata scsi_mod xen_blkfront xen_netfront fb_sys_fops sysimgblt sysfillr
    cmd
    
    Pid: 2307, comm: ip Not tainted 3.3.0-rc1 #1 Xen HVM domU
    RIP: 0010:[<ffffffff81375ae9>]  [<ffffffff81375ae9>] gnttab_end_foreign_access_ref_v2+0x29/0x40
    RSP: 0018:ffff88003be03d38  EFLAGS: 00010206
    RAX: 0000000000000000 RBX: ffff880033210640 RCX: 0000000000000040
    RDX: 0000000000002000 RSI: 0000000000000000 RDI: 0000000000000200
    RBP: ffff88003be03d38 R08: 0000000000000101 R09: 0000000000000000
    R10: dead000000100100 R11: 0000000000000000 R12: ffff88003be03e48
    R13: 0000000000000001 R14: ffff880039461c00 R15: 0000000000000200
    FS:  00007fb1f84ec700(0000) GS:ffff88003be00000(0000) knlGS:0000000000000000
    ...

It should be implemented at some point.. but since there are no real
users of V2 it is a the bottom of the pile of 'todo'.

> there's no v2 support:
> 
> http://lxr.free-electrons.com/source/drivers/xen/grant-table.c#L1116
> 
> As Wei points out, you can safely use v1 for all kind of guests, at
> least on x86.
> 
> Roger.
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

Re: sources of freebsd with xen-4.2 kernel updates

[Igor Kozhukhov]

On Dec 30, 2013, at 3:25 PM, Roger Pau Monné wrote:

> On 30/12/13 11:57, Igor Kozhukhov wrote:
>> Hi Roger,
>> 
>> thanks for the link.
>> I have the same/(similar the same) implementation on illumos(OpenSolaris).
>> 
>> do you have plans for grant table v1 & v2 implementation on FreeBSD ?
> 
> Grant table v1 is the current implementation, and I don't have plans
> currently to add support for v2 (cannot speak of others though).
> 
> Linux has v2 implemented, but AFAIK there's no user of the new features
> introduced by v2. Right now with v2 you just end up with less grants,
> because v2 grants metadata use twice as much memory as v1 grants, and
> the number of grant frames is limited by the hypervisor.
> 

Thank you all for your info.

I have just tested it and can see that PV and HVM guests are using V1 if V2 not implemented on dom0 - for example: on xen-3.4 hypervisor.

well - my first step for xen-4.2 port to illumos based platform have progress :)
after updates xen-4.2 public headers with grant tables and some additional changes, PV and HVM guests works on xen-3.4 dom0.

i have DilOS(illumos based platform) with xen-3.4.5-pre1(latest updates on 3.4) as dom0.
i'm interested in xen-4.2 port with next updates to xen-4.4.

-Igor


> Roger.
> 

Re: sources of freebsd with xen-4.2 kernel updates

[Konrad Rzeszutek Wilk]

On Mon, Dec 30, 2013 at 04:59:42PM +0400, Igor Kozhukhov wrote:
> On Dec 30, 2013, at 3:25 PM, Roger Pau Monné wrote:
> 
> > On 30/12/13 11:57, Igor Kozhukhov wrote:
> >> Hi Roger,
> >> 
> >> thanks for the link.
> >> I have the same/(similar the same) implementation on illumos(OpenSolaris).
> >> 
> >> do you have plans for grant table v1 & v2 implementation on FreeBSD ?
> > 
> > Grant table v1 is the current implementation, and I don't have plans
> > currently to add support for v2 (cannot speak of others though).
> > 
> > Linux has v2 implemented, but AFAIK there's no user of the new features
> > introduced by v2. Right now with v2 you just end up with less grants,
> > because v2 grants metadata use twice as much memory as v1 grants, and
> > the number of grant frames is limited by the hypervisor.
> > 
> 
> Thank you all for your info.
> 
> I have just tested it and can see that PV and HVM guests are using V1 if V2 not implemented on dom0 - for example: on xen-3.4 hypervisor.
> 
> well - my first step for xen-4.2 port to illumos based platform have progress :)

Woot!
> after updates xen-4.2 public headers with grant tables and some additional changes, PV and HVM guests works on xen-3.4 dom0.
> 
> i have DilOS(illumos based platform) with xen-3.4.5-pre1(latest updates on 3.4) as dom0.
> i'm interested in xen-4.2 port with next updates to xen-4.4.
> 
> -Igor
> 
> 
> > Roger.
> > 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel