On 31/08/16 16:06, Konrad Rzeszutek Wilk wrote:
On Wed, Aug 31, 2016 at 03:49:55PM +0100, Julien Grall wrote:
On 25/08/16 14:37, Konrad Rzeszutek Wilk wrote:
Hey!
Hi Konrad,
Since v1 (and RFC):
[https://lists.xen.org/archives/html/xen-devel/2016-08/msg01835.html]
- Acted on most all comments.
- Added ARM32 support.
The patches are based on: [PATCH v4] Livepatch fixes and features for v4.8.
(https://lists.xen.org/archives/html/xen-devel/2016-08/msg02705.html)
And the git tree is:
git://xenbits.xen.org/people/konradwilk/xen.git livepatch.v4.8.v4
There are two outstanding questions that should be addressed at some point:
- #16 "livepatch: tests: Make them compile under ARM64"
We chatted about adding a specific CPU bit (LIVEPATCH) so that alternative
code always gets exercised. This being for both x86 and ARM. But this has
a side effect that it gets exposed to the toolstack and can also be
exposed to the guests. I think it is better if we do not do that
so left it to be enabled based on the most common errata (or feature
on x86).
There is no common errata on ARM. I spoke with Andrew which mentioned that
on x86 they have architectural xen feature bits which are not exposed to the
toolstack/guest.
Furthermore, I think it would be unwise to let the toolstack aware of some
errata and possibly setting/clearing them. So adding a specific feature bit
is fine by me.
So you are thinking of exposing this 'xen feature bits' that Andrew mention
to be on ARM as well.
I only chat with Andrew about it and I have not looked at the code, so I
can't tell how it is on x86. I was just thinking to add LIVEPATCH bit in
cpufeature.h for now and be worry later when cpufeature will be exposed
to the toolstack for ARM.
Cheers,
--
Julien Grall
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