From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: Proposed XENMEM_claim_pages hypercall: Analysis of
 problem and alternate solutions
Date: Fri, 11 Jan 2013 14:08:14 -0500
Message-ID: <20130111190814.GD29020@phenom.dumpdata.com>
References: <mailman.18000.1354568068.1399.xen-devel@lists.xen.org>
	<49049C00-89CA-4B43-9660-83B9ADC061E0@gridcentric.ca>
	<20121218221749.GA6332@phenom.dumpdata.com>
	<AF146C82-5904-480C-80D0-7906AFD2B614@gridcentric.ca>
	<20130111160314.GD15353@phenom.dumpdata.com>
	<F2749668-D894-4DBA-BC48-D5CE8180C27F@gridcentric.ca>
Mime-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: base64
Return-path: <xen-devel-bounces@lists.xen.org>
Content-Disposition: inline
In-Reply-To: <F2749668-D894-4DBA-BC48-D5CE8180C27F@gridcentric.ca>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Andres Lagar-Cavilla <andreslc@gridcentric.ca>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>, "Keir (Xen.org)" <keir@xen.org>, Ian Campbell <ian.campbell@citrix.com>, George Dunlap <George.Dunlap@eu.citrix.com>, Ian Jackson <Ian.Jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>, xen-devel@lists.xen.org, Konrad Rzeszutek Wilk <konrad@kernel.org>, Jan Beulich <JBeulich@suse.com>
List-Id: xen-devel@lists.xenproject.org

PiA+Pj4+IE5laXRoZXIgaXMgZW5mb3JjaW5nIG1pbj09bWF4LiBUaGlzIHdhcyBteSBhcmd1bWVu
dCB3aGVuIHByZXZpb3VzbHkgY29tbWVudGluZyBvbiB0aGlzIHRocmVhZC4gVGhlIGZhY3QgdGhh
dCB5b3UgaGF2ZSBlbmZvcmNlbWVudCBvZiBhIG1heGltdW0gZG9tYWluIGFsbG9jYXRpb24gZ2l2
ZXMgeW91IGFuIGV4Y2VsbGVudCB0b29sIHRvIGtlZXAgYSBkb21haW4ncyB1bnN1cGVydmlzZWQg
Z3Jvd3RoIGF0IGJheS4gVGhlIHRvb2xzdGFjayBjYW4gY2hvb3NlIGhvdyBmaW5lLWdyYWluZWQs
IGhvdyBvZnRlbiB0byBiZSBhbGVydGVkIGFuZCBzdGFsbCB0aGUgZG9tYWluLgo+ID4gCj4gPiBU
aGF0IHdvdWxkIGFsc28gZG8gdGhlIHRyaWNrIC0gYnV0IHRoZXJlIGFyZSBwZW5hbHRpZXMgdG8g
aXQuCj4gPiAKPiA+IElmIG9uZSBqdXN0IHdhbnRzIHRvIGxhdW5jaCBtdWx0aXBsZSBndWVzdHMg
YW5kICJmcmVlemUiIGFsbCB0aGUgb3RoZXIgZ3Vlc3RzCj4gPiBmcm9tIHVzaW5nIHRoZSBiYWxs
b29uIGRyaXZlciAtIHRoYXQgY2FuIGNlcnRhaW5seSBiZSBkb25lLgo+ID4gCj4gPiBCdXQgdGhh
dCBpcyBhIGhhbGYtd2F5IHNvbHV0aW9uIChpbiBteSBtaW5kKS4gRGFuJ3MgaWRlYSBpcyB0aGF0
IHlvdSB3b3VsZG4ndAo+ID4gZXZlbiBuZWVkIHRoYXQgYW5kIGNhbiBqdXN0IGFsbG9jYXRlIHdp
dGhvdXQgaGF2aW5nIHRvIHdvcnJ5IGFib3V0IHRoZSBvdGhlcgo+ID4gZ3Vlc3RzIGF0IGFsbCAt
IGIvYyB5b3UgaGF2ZSByZXNlcnZlZCBlbm91Z2ggbWVtb3J5IGluIHRoZSBoeXBlcnZpc29yICho
b3N0KSB0bwo+ID4gbGF1bmNoIHRoZSBndWVzdC4KPiAKPiBLb25yYWQ6Cj4gT2ssIHdoYXQgaGFw
cGVucyB3aGVuIGEgZ3Vlc3QgaXMgc3RhbGxlZCBiZWNhdXNlIGl0IGNhbm5vdCBhbGxvY2F0ZSBt
b3JlIHBhZ2VzIGR1ZSB0byBleGlzdGluZyBjbGFpbXM/IEV4YWN0bHkgdGhlIHNhbWUgdGhhdCBo
YXBwZW5zIHdoZW4gaXQgY2FuJ3QgZ3JvdyBiZWNhdXNlIGl0IGhhcyBoaXQgZC0+bWF4X3BhZ2Vz
LgoKQnV0IGl0IHdvdWxkbid0LiBJIGFtIGdvaW5nIGhlcmUgb24gYSBsaW1wLCBiL2MgSSBiZWxp
ZXZlIHRoaXMgaXMgd2hhdCB0aGUgY29kZQpkb2VzIGJ1dCBJIHNob3VsZCBkb3VibGUtY2hlY2su
CgpUaGUgdmFyaWFibGVzIGZvciB0aGUgZ3Vlc3QgdG8gZ28gdXAvZG93biB3b3VsZCBzdGlsbCBz
dGF5IGluIHBsYWNlIC0gc28gaXQKc2hvdWxkIG5vdCBiZSBpbXBhY3RlZCBieSB0aGUgJ2NsYWlt
Jy4gTWVhbmluZyB5b3UganVzdCBsZWF2ZSB0aGVtIGFsb25lCmFuZCBsZXQgdGhlIGd1ZXN0IGRv
IHdoYXRldmVyIGl0IHdhbnRzIHdpdGhvdXQgaW5mbHVlbmNpbmcgaXQuCgpJZiB0aGUgY2xhaW0g
aHlwZXJjYWxsIGZhaWxzLCB0aGVuIHllcyAtIHlvdSBjb3VsZCBoYXZlIHRoaXMgaXNzdWUuCgpC
dXQgdGhlIHNvbHV0aW9uIHRvIHRoZSBoeXBlcmNhbGwgZmFpbGluZyBhcmUgbXVsdGlwbGUgLSBv
bmUgaXMgdG8gCnRyeSB0byAic3F1ZWV6ZSIgYWxsIHRoZSBndWVzdHMgdG8gbWFrZSBzcGFjZSBv
ciBqdXN0IHRyeSB0byBhbGxvY2F0ZQp0aGUgZ3Vlc3Qgb24gYW5vdGhlciBib3ggdGhhdCBoYXMg
bW9yZSBtZW1vcnkgYW5kIHdoZXJlIHRoZSBjbGFpbQpoeXBlcmNhbGwgcmV0dXJuZWQgc3VjY2Vz
cy4gT3IgaXQgY2FuIGRvIHRoZXNlIGNsYWltIGh5cGVyY2FsbHMKb24gYWxsIHRoZSBub2RlcyBp
biBwYXJhbGxlbCBhbmQgcGljayBhbW9uZ3N0IHRoZSBvbmVzIHRoYXQgcmV0dXJuZWQKc3VjY2Vz
cy4KClBlcmhhcHMgdGhlICdjbGFpbScgY2FsbCBzaG91bGQgYmUgY2FsbGVkICdwcm9iZV9hbmRf
Y2xhaW0nPwoKLi4gc25pcC4uCj4gPj4+IFRoYXQgY29kZSBtYWtlcyBjZXJ0YWluIGFzc3VtcHRp
b25zIC0gdGhhdCB0aGUgZ3Vlc3Qgd2lsbCBub3QgZ28vdXAgZG93bgo+ID4+PiBpbiB0aGUgYmFs
bG9vbmluZyBvbmNlIHRoZSB0b29sc3RhY2sgaGFzIGRlY3JlZWQgaG93IG11Y2gKPiA+Pj4gbWVt
b3J5IHRoZSBndWVzdCBzaG91bGQgdXNlLiBJdCBhbHNvIGFzc3VtZXMgdGhhdCB0aGUgb3BlcmF0
aW9ucwo+ID4+PiBhcmUgc2VtaS1hdG9taWMgLSBhbmQgdG8gbWFrZSBpdCBzbyBhcyBtdWNoIGFz
IGl0IGNhbiAtIGl0IGV4ZWN1dGVzCj4gPj4+IHRoZXNlIG9wZXJhdGlvbnMgaW4gc2VyaWFsLgo+
ID4+PiAKPiA+Pj4gVGhpcyBnb2VzIGJhY2sgdG8gdGhlIHByb2JsZW0gc3RhdGVtZW50IC0gaWYg
d2UgdHJ5IHRvIHBhcmFsbGl6ZQo+ID4+PiB0aGlzIHdlIHJ1biBpbiB0aGUgcHJvYmxlbSB0aGF0
IHRoZSBhbW91bnQgb2YgbWVtb3J5IHdlIHRob3VnaHQKPiA+Pj4gd2UgZnJlZSBpcyBub3QgdHJ1
ZSBhbnltb3JlLiBUaGUgc3RhcnQgb2YgdGhpcyBlbWFpbCBoYXMgYSBnb29kCj4gPj4+IGRlc2Ny
aXB0aW9uIG9mIHNvbWUgb2YgdGhlIGlzc3Vlcy4KPiA+PiAKPiA+PiBKdXN0IHNldCBtYXhfcGFn
ZXMgKGJhZCBuYW1lLi4uKSBldmVyeXdoZXJlIGFzIG5lZWRlZCB0byBtYWtlIHJvb20uIFRoZW4g
a2ljayB0bWVtIChldmVyeXdoZXJlLCBpbiBwYXJhbGxlbCkgdG8gZnJlZSBtZW1vcnkuIFdhaXQg
dW50aWwgZW5vdWdoIGlzIGZyZWUg4oCmLiBBbGxvY2F0ZSB5b3VyIGRvbWFpbihzLCBpbiBwYXJh
bGxlbCkuIElmIGFueSB2Y3B1cyBiZWNvbWUgc3RhbGxlZCBiZWNhdXNlIGEgdG1lbSBndWVzdCBk
cml2ZXIgaXMgdHJ5aW5nIHRvIGFsbG9jYXRlIGJleW9uZCBtYXhfcGFnZXMsIHlvdSBuZWVkIHRv
IGFkanVzdCB5b3VyIGFsbG9jYXRpb25zLiBBcyB1c3VhbC4KPiA+IAo+ID4gCj4gPiBWZXJzdXMg
anVzdCBvbmUgInJlc2VydmUiIHRoYXQgd291bGQgcmVtb3ZlIHRoZSBuZWVkIGZvciBtb3N0IG9m
IHRoaXMuCj4gPiBUaGF0IGlzIC0gaWYgd2UgY2FuIG5vdCAicmVzZXJ2ZSIgd2Ugd291bGQgZmFs
bC1iYWNrIHRvIHRoZSBtZWNoYW5pc20geW91Cj4gPiBzdGF0ZWQsIGJ1dCBpZiB0aGVyZSBpcyBl
bm91Z2ggbWVtb3J5IHdlIGRvIG5vdCBoYXZlIHRvIGRvIHRoZSAid2FpdCIKPiA+IGdhbWUgKHdo
aWNoIG9uIGEgMVRCIHRha2VzIGZvcmV2ZXIgYW5kIG1ha2VzIGxhdW5jaGluZyBndWVzdHMgc29t
ZXRpbWVzCj4gPiB0YWtlIG1pbnV0ZXMpIC0gYW5kIGNhbiBsYXVuY2ggdGhlIGd1ZXN0IHdpdGhv
dXQgaGF2aW5nIHRvIHdvcnJ5Cj4gPiBhYm91dCBzbG93LXBhdGguCj4gPiAuLiBzbmlwLgo+IAo+
IFRoZSAid2FpdCIgY291bGQgYmUgbGl0ZXJhbGx5IHplcm8gaW4gYSBjb21tb24gY2FzZS4gQW5k
IGlmIG5vdCwgYmVjYXVzZSB0aGVyZSBpcyBub3QgZW5vdWdoIGZyZWUgcmFtLCB0aGUgY2xhaW0g
d291bGQgaGF2ZSBmYWlsZWQuCj4gCgpBYnNvbHV0bHkuIEFuZCB0aGF0IGlzIHRoZSBiZWF0eSBv
ZiBpdC4gSWYgaXQgZmFpbHMgdGhlbiB3ZSBjYW4KZGVjaWRlIHRvIHBlcnN1ZSBvdGhlciBvcHRp
b25zIGtub3dpbmcgdGhhdCB0aGVyZSB3YXMgbm8gcmFjZSBpbiBmaW5kaW5nCnRoZSB2YWx1ZSBv
ZiBmcmVlIG1lbW9yeSBhdCBhbGwuIFRoZSBvdGhlciBvcHRpb25zIGNvdWxkIGJlIHRoZQpzcXVl
ZXplIG90aGVyIGd1ZXN0cyBkb3duIGFuZCB0cnkgYWdhaW47IG9yIGp1c3QgZGVjaWRlIHRvIGNs
YWltL2FsbG9jYXRlCnRoZSBndWVzdCBvbiBhbm90aGVyIGhvc3QgYWx0b2dldGhlci4KCgo+ID4+
PiBJIGJlbGlldmUgRGFuIGlzIHNheWluZyBpcyB0aGF0IGl0IGlzIG5vdCBlbmFibGVkIGJ5IGRl
ZmF1bHQuCj4gPj4+IE1lYW5pbmcgaXQgZG9lcyBub3QgZ2V0IGV4ZWN1dGVkIGluIGJ5IC9ldGMv
aW5pdC5kL3hlbmNvbW1vbnMgYW5kCj4gPj4+IGFzIHN1Y2ggaXQgbmV2ZXIgZ2V0cyBydW4gKG9y
IGRvZXMgaXQgbm93PykgLSB1bmxlc3Mgb25lIGtub3dzCj4gPj4+IGFib3V0IGl0IC0gb3IgaXQg
aXMgZW5hYmxlZCBieSBkZWZhdWx0IGluIGEgcHJvZHVjdC4gQnV0IHBlcmhhcHMKPiA+Pj4gd2Ug
YXJlIGJvdGggbWlzdGFrZW4/IElzIGl0IGVuYWJsZWQgYnkgZGVmYXVsdCBub3cgb24gZGVuLXVu
c3RhYmxlPwo+ID4+IAo+ID4+IEknbSBhIGJpdCBsb3N0IOKApiB3aGF0IGlzIHN1cHBvc2VkIHRv
IGJlIGVuYWJsZWQ/IEEgc2hhcmluZyBkYWVtb24/IEEgcGFnaW5nIGRhZW1vbj8gTmVpdGhlciBk
YWVtb24gcmVxdWlyZXMgd2FpdCBxdWV1ZSB3b3JrLCBiYXRjaCBhbGxvY2F0aW9ucywgZXRjLiBJ
IGNhbid0IGZpZ3VyZSBvdXQgd2hhdCB0aGlzIHBvcnRpb24gb2YgdGhlIGNvbnZlcnNhdGlvbiBp
cyBhYm91dC4KPiA+IAo+ID4gVGhlIHhlbnNoYXJlZCBkYWVtb24uCj4gVGhhdCdzIG5vdCBpbiB0
aGUgdHJlZS4gVW5iZWtub3duc3QgdG8gbWUuIFdvdWxkIGFwcHJlY2lhdGUgdG8ga25vdyBtb3Jl
LiBPciBpcyBpdCBhIHN5bWJvbGljIHBsYWNlaG9sZGVyIGluIHRoaXMgY29udmVyc2F0aW9uPwoK
T0ssIEkgYW0gY29uZnVzZWQgdGhlbi4gSSB0aG91Z2h0IHRoZXJlIHdhcyBub3cgYW4gZGFlbW9u
IHRoYXQgd291bGQgdGFrZQpjYXJlIG9mIHRoZSBQb0QgYW5kIHN3YXBwaW5nPyBQZXJoYXBzIGl0
cyBjYWxsZWQgc29tZXRoaW5nIGVsc2U/CgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f
X19fX19fX19fX19fX19fXwpYZW4tZGV2ZWwgbWFpbGluZyBsaXN0Clhlbi1kZXZlbEBsaXN0cy54
ZW4ub3JnCmh0dHA6Ly9saXN0cy54ZW4ub3JnL3hlbi1kZXZlbAo=