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From: "Wieczorkiewicz, Pawel" <wipawel@amazon.de>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tim Deegan <tim@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
	Ross Lagerwall <ross.lagerwall@citrix.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	xen-devel <xen-devel@lists.xen.org>,
	"Pohlack, Martin" <mpohlack@amazon.de>,
	"Wieczorkiewicz, Pawel" <wipawel@amazon.de>,
	Julien Grall <julien.grall@arm.com>,
	Jan Beulich <jbeulich@suse.com>,
	xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [Xen-devel] [PATCH v2 05/12] livepatch: Add support for apply|revert action replacement hooks
Date: Wed, 28 Aug 2019 07:37:22 +0000
Message-ID: <F3A43E49-6F04-49A8-A5AD-5BABC14A02F2@amazon.com> (raw)
In-Reply-To: <AC4BE922-88D7-47B9-9CEC-D9413B22AB61@oracle.com>

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On 27. Aug 2019, at 18:58, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com<mailto:konrad.wilk@oracle.com>> wrote:

On August 27, 2019 4:46:17 AM EDT, Pawel Wieczorkiewicz <wipawel@amazon.de<mailto:wipawel@amazon.de>> wrote:
By default, in the quiescing zone, a hotpatch payload is applied with
apply_payload() and reverted with revert_payload() functions. Both of
the functions receive the payload struct pointer as a parameter. The
functions are also a place where standard 'load' and 'unload' module
hooks are executed.

To increase hotpatching system's agility and provide more flexiable
long-term hotpatch solution, allow to overwrite the default apply
and revert action functions with hook-like supplied alternatives.
The alternative functions are optional and the default functions are
used by default.

Is there sense in having the old ones anymore? We could just remove them altogether and just use the new ones instead from the start?


Yes, I believe there is. The old ones represent well-tested, proven way of
payload application (or revert) which preserves conservative behavior of the system
via enforcing certain assumptions.
The old ones cover 99% of the production use cases, so I would insist on keeping
them in (at least for now).

Later, we could modify livepatch-build-tools to always generate the original
apply|revert functions (in a default case) as part of payloads (hooks).
But, I would not do it just now.

Best Regards,
Pawel Wieczorkiewicz






Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879



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<br class="">
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<blockquote type="cite" class="">
<div class="">On 27. Aug 2019, at 18:58, Konrad Rzeszutek Wilk &lt;<a href="mailto:konrad.wilk@oracle.com" class="">konrad.wilk@oracle.com</a>&gt; wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div class="">On August 27, 2019 4:46:17 AM EDT, Pawel Wieczorkiewicz &lt;<a href="mailto:wipawel@amazon.de" class="">wipawel@amazon.de</a>&gt; wrote:<br class="">
<blockquote type="cite" class="">By default, in the quiescing zone, a hotpatch payload is applied with<br class="">
apply_payload() and reverted with revert_payload() functions. Both of<br class="">
the functions receive the payload struct pointer as a parameter. The<br class="">
functions are also a place where standard 'load' and 'unload' module<br class="">
hooks are executed.<br class="">
<br class="">
To increase hotpatching system's agility and provide more flexiable<br class="">
long-term hotpatch solution, allow to overwrite the default apply<br class="">
and revert action functions with hook-like supplied alternatives.<br class="">
The alternative functions are optional and the default functions are<br class="">
used by default.<br class="">
</blockquote>
<br class="">
Is there sense in having the old ones anymore? We could just remove them altogether and just use the new ones instead from the start?<br class="">
<br class="">
</div>
</div>
</blockquote>
</div>
<div class=""><br class="">
</div>
Yes, I believe there is. The old ones represent well-tested, proven way of
<div class="">payload application (or revert) which preserves conservative behavior of the system</div>
<div class="">via enforcing certain assumptions.</div>
<div class="">The old ones cover 99% of the production use cases, so I would insist on keeping
<div class="">them in (at least for now).</div>
<div class=""><br class="">
</div>
<div class="">Later, we could modify livepatch-build-tools to always generate the original</div>
<div class="">apply|revert functions (in a default case) as part of payloads (hooks).</div>
<div class="">But, I would not do it just now.</div>
<div class=""><br class="">
</div>
<div class="">
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">
<div style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
Best Regards,<br class="">
Pawel Wieczorkiewicz</div>
<br class="Apple-interchange-newline">
</div>
<br class="Apple-interchange-newline">
</div>
<br class="">
</div>
<br><br><br>Amazon Development Center Germany GmbH
<br>Krausenstr. 38
<br>10117 Berlin
<br>Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich
<br>Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
<br>Sitz: Berlin
<br>Ust-ID: DE 289 237 879
<br><br><br>
</body>
</html>

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Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-21  8:19 [Xen-devel] [PATCH 00/14] livepatch: new features and fixes Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 01/14] livepatch: Always check hypervisor build ID upon hotpatch upload Pawel Wieczorkiewicz
2019-08-21 18:16   ` Konrad Rzeszutek Wilk
2019-08-21  8:19 ` [Xen-devel] [PATCH 02/14] livepatch: Allow to override inter-modules buildid dependency Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 03/14] python: Add XC binding for Xen build ID Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 04/14] livepatch: Export payload structure via livepatch_payload.h Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 05/14] livepatch: Implement pre-|post- apply|revert hooks Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 06/14] livepatch: Add support for apply|revert action replacement hooks Pawel Wieczorkiewicz
2019-08-21 18:31   ` Konrad Rzeszutek Wilk
2019-08-21 19:06     ` Wieczorkiewicz, Pawel
2019-08-26 14:30       ` Konrad Rzeszutek Wilk
2019-08-21  8:19 ` [Xen-devel] [PATCH 07/14] livepatch: Do not enforce ELF_LIVEPATCH_FUNC section presence Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 08/14] livepatch: always print XENLOG_ERR information Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 09/14] livepatch: Add per-function applied/reverted state tracking marker Pawel Wieczorkiewicz
2019-08-21 18:28   ` Konrad Rzeszutek Wilk
2019-08-21 19:00     ` Wieczorkiewicz, Pawel
2019-08-21 21:34   ` Julien Grall
2019-08-22  7:44     ` Wieczorkiewicz, Pawel
2019-08-22 10:07       ` Julien Grall
2019-08-22 10:20         ` Wieczorkiewicz, Pawel
2019-08-22 10:43           ` Julien Grall
2019-08-22 11:15             ` Wieczorkiewicz, Pawel
2019-08-22 15:02               ` Julien Grall
2019-08-22 10:29   ` Julien Grall
2019-08-22 11:02     ` Wieczorkiewicz, Pawel
2019-08-22 15:30       ` Julien Grall
2019-08-22 15:42         ` Wieczorkiewicz, Pawel
2019-08-21  8:19 ` [Xen-devel] [PATCH 10/14] livepatch: Add support for inline asm hotpatching expectations Pawel Wieczorkiewicz
2019-08-21 18:30   ` Konrad Rzeszutek Wilk
2019-08-21 19:02     ` Wieczorkiewicz, Pawel
2019-08-22 10:31   ` Julien Grall
2019-08-22 11:03     ` Wieczorkiewicz, Pawel
2019-08-21  8:19 ` [Xen-devel] [PATCH 11/14] livepatch: Add support for modules .modinfo section metadata Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 12/14] livepatch: Handle arbitrary size names with the list operation Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 13/14] livepatch: Add metadata runtime retrieval mechanism Pawel Wieczorkiewicz
2019-08-21  8:19 ` [Xen-devel] [PATCH 14/14] livepatch: Add python bindings for livepatch operations Pawel Wieczorkiewicz
2019-08-22 21:55   ` Marek Marczykowski-Górecki
2019-08-27  8:46 ` [Xen-devel] [PATCH v2 00/12] livepatch: new features and fixes Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 01/12] livepatch: Always check hypervisor build ID upon hotpatch upload Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 02/12] livepatch: Allow to override inter-modules buildid dependency Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 03/12] livepatch: Export payload structure via livepatch_payload.h Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 04/12] livepatch: Implement pre-|post- apply|revert hooks Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 05/12] livepatch: Add support for apply|revert action replacement hooks Pawel Wieczorkiewicz
2019-08-27 16:58     ` Konrad Rzeszutek Wilk
2019-08-28  7:37       ` Wieczorkiewicz, Pawel [this message]
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 06/12] livepatch: Do not enforce ELF_LIVEPATCH_FUNC section presence Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 07/12] livepatch: Add per-function applied/reverted state tracking marker Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 08/12] livepatch: Add support for inline asm hotpatching expectations Pawel Wieczorkiewicz
2019-08-29 14:34     ` Konrad Rzeszutek Wilk
2019-08-29 15:29       ` Wieczorkiewicz, Pawel
2019-08-29 15:58     ` Konrad Rzeszutek Wilk
2019-08-29 16:16       ` Wieczorkiewicz, Pawel
2019-08-29 17:49         ` Konrad Rzeszutek Wilk
2019-08-29 19:07           ` Wieczorkiewicz, Pawel
2019-08-29 20:48             ` Konrad Rzeszutek Wilk
2019-09-05 18:05     ` Konrad Rzeszutek Wilk
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 09/12] livepatch: Add support for modules .modinfo section metadata Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 10/12] livepatch: Handle arbitrary size names with the list operation Pawel Wieczorkiewicz
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 11/12] livepatch: Add metadata runtime retrieval mechanism Pawel Wieczorkiewicz
2019-08-29 20:48     ` Konrad Rzeszutek Wilk
2019-08-27  8:46   ` [Xen-devel] [PATCH v2 12/12] livepatch: Add python bindings for livepatch operations Pawel Wieczorkiewicz
2019-08-28 13:21     ` Marek Marczykowski-Górecki
2019-08-29 19:23   ` [Xen-devel] [PATCH v2 00/12] livepatch: new features and fixes Konrad Rzeszutek Wilk
2019-09-05 19:13   ` Konrad Rzeszutek Wilk
2019-09-06 22:52     ` Julien Grall
2019-09-06 22:42   ` Julien Grall

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