Re: [Xen-devel] [PATCH lp-metadata 3/3] livepatch: Add metadata runtime retrieval mechanism

From: Wei Liu <wl@xen.org>
To: Pawel Wieczorkiewicz <wipawel@amazon.de>
Cc: Tim Deegan <tim@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	xen-devel@lists.xen.org, mpohlack@amazon.de,
	Ross Lagerwall <ross.lagerwall@citrix.com>,
	Julien Grall <julien.grall@arm.com>,
	Jan Beulich <jbeulich@suse.com>,
	xen-devel@lists.xenproject.org
Subject: Re: [Xen-devel] [PATCH lp-metadata 3/3] livepatch: Add metadata runtime retrieval mechanism
Date: Fri, 16 Aug 2019 12:44:45 +0000	[thread overview]
Message-ID: <20190816124445.n767e5yra4zodt3z@liuwe-gateway.j3c5onc20sse1dnehy4noqpfcg.zx.internal.cloudapp.net> (raw)
In-Reply-To: <20190815112750.11581-1-wipawel@amazon.de>

On Thu, Aug 15, 2019 at 11:27:50AM +0000, Pawel Wieczorkiewicz wrote:
> Extend the livepatch list operation to fetch also payloads' metadata.
> This is achieved by extending the sysctl list interface with 2 extra
> guest handles:
> * metadata     - an array of arbitrary size strings
> * metadata_len - an array of metadata strings' lengths (uin32_t each)
> 
> Payloads' metadata is a string of arbitrary size and does not have an
> upper bound limit. It may also vary in size between payloads.
> 
> In order to let the userland allocate enough space for the incoming
> data add a metadata total size field to the list sysctl operation and
> fill it with total size of all payloads' metadata.
> 
> Extend the libxc to handle the metadata back-to-back data transfers
> as well as metadata length array data transfers.
> 
> The xen-livepatch userland tool is extended to always display the
> metadata for each received module. The metadata is received with the
> following format: key=value\0key=value\0...key=value\0. The format is
> modified to the following one: key=value;key=value;...key=value.
> The new format allows to easily parse the metadata for a given module
> by a machine.
> 
> Signed-off-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
> Reviewed-by: Andra-Irina Paraschiv <andraprs@amazon.com>
> Reviewed-by: Martin Pohlack <mpohlack@amazon.de>
> Reviewed-by: Norbert Manthey <nmanthey@amazon.de>
> ---
>  tools/libxc/include/xenctrl.h | 22 +++++++++++----
>  tools/libxc/xc_misc.c         | 66 +++++++++++++++++++++++++++++++++++--------
>  tools/misc/xen-livepatch.c    | 43 ++++++++++++++++++++++------
>  xen/common/livepatch.c        | 22 +++++++++++----
>  xen/include/public/sysctl.h   | 19 +++++++++----

Mostly look good. One comment below...

> diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
> index b86804b7a6..e4c8f4fe63 100644
> --- a/xen/include/public/sysctl.h
> +++ b/xen/include/public/sysctl.h

If it hasn't been done for this release already, changing sysctl interface requires
bumping the version number in this header.

Wei.

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