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Re: [Xen-devel] preparations for 4.9.2 and 4.7.5

Hi Stefano,

On 04/04/18 00:55, Stefano Stabellini wrote:
On Tue, 3 Apr 2018, Julien Grall wrote:

On 16/03/18 17:15, Julien Grall wrote:

On 16/03/2018 16:56, Julien Grall wrote:
Hi Stefano,

On 16/03/2018 16:33, Stefano Stabellini wrote:
On Fri, 16 Mar 2018, Julien Grall wrote:
Hi Stefano,

On 15/03/18 23:52, Stefano Stabellini wrote:
On Wed, 14 Mar 2018, Stefano Stabellini wrote:
After looking at the test results, which are good for arm, and
considering that master hasn't passed yet after 2 more days, I
with Julien: I think we should not release 4.9.2 and 4.7.5 without
arm64 spectre patches. At this point, I'll proceed to backport the
patches now.

Julien, Andre,

Please give a look at the following branches:


For all of the tree above, as I said yesterday, I clearly don't want
to see
the smccc framework backport for Xen 4.9 and older. This is a massive
of the interface that is not necessary for spectre. My main concern is
SMC instruction available to the guest.

It would be just sufficient to emulate the few SMCCC function ID we
care in
do_trap_psci (function can be renamed).

This is also clearly wrong to backport coding style or code
non-justified code
movement (sysreg) just to please the cherry-pick.

I am also worry to bump the version of the emulated PSCI (0.2 -> 1.0)
those releases. Some guests may rely on a specific version and may now

Overall, the right way to support spectre in earlier releases is
custom patch
and only do minimal modification.


The patches below should not be part of spectre nor backport to 4.10:
    - 82e29c87dc7f4f2a7e2f111c3646479da21a910a "ARM: remove unneeded
    - 79563717c9dd5383abcf0ba94d813de9b42e3793 "xen/arm: psci: Prefix
static any functions not exported"
    - 6d0e9b21b1f7213c1994cc2d636448ee2d5372c2 "xen/arm: vpsci: Update
return type for MIGRATE_INFO_TYPE"

The patches below should not be part of spectre but candidate to 4.10:
    - c2d70f77cc7987be164cd87b76459782497fc540 "xen/arm: vpsci: Rework
the logic
to start AArch32 vCPU in Thumb mode"

You will also want to backport [1] which address a relaxation of the

I understand your concerns, in that case could you please provide the
git branches?

That will have to wait when I have spare cycle. Most likely somewhere in
April when I am done from the Xen 4.11 patches and back from holidays.

So It is probably the right time to put into contribution stakeholders who
are using those Xen 4.* stable releases.

To be clear, for Xen 4.10 it is just a matter of dropping the 3 patches I
suggested. There are actually no clash with the current code.

Gentle ping. Is there anything blocking to get those patches in Xen 4.10?

Done! Thanks for the ping!

It looks like the commit 6b270fae7ad462687550a875f714bff18d764416 "xen/arm: Relax ARM_SMCCC_ARCH_WORKAROUND_1 discovery" is missing in Xen 4.10.


Julien Grall

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