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

[Lars Kurth <lars.kurth@xxxxxxxxxx>]

Folks,
I have not created the webpages for these. The script I am using to generate 
these depends on a script in xsa.git, which fails at the moment due to a 
missing new package dependency that I can't resolve as I don't have root access
Lars 

On 04/04/2018, 10:59, "Julien Grall" <julien.grall@xxxxxxx> wrote:

    Hi Stefano,
    
    On 04/04/18 00:55, Stefano Stabellini wrote:
    > On Tue, 3 Apr 2018, Julien Grall wrote:
    >> Hi,
    >>
    >> 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
    >>>>>>>> agree
    >>>>>>>> with Julien: I think we should not release 4.9.2 and 4.7.5 without
    >>>>>>>> the
    >>>>>>>> arm64 spectre patches. At this point, I'll proceed to backport the
    >>>>>>>> patches now.
    >>>>>>>
    >>>>>>> Julien, Andre,
    >>>>>>>
    >>>>>>> Please give a look at the following branches:
    >>>>>>>
    >>>>>>> git://xenbits.xen.org/people/sstabellini/xen-unstable.git
    >>>>>>> staging-4.7-spectre
    >>>>>>> git://xenbits.xen.org/people/sstabellini/xen-unstable.git
    >>>>>>> staging-4.8-spectre
    >>>>>>> git://xenbits.xen.org/people/sstabellini/xen-unstable.git
    >>>>>>> staging-4.9-spectre
    >>>>>>
    >>>>>> 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
    >>>>>> changes
    >>>>>> of the interface that is not necessary for spectre. My main concern 
is
    >>>>>> making
    >>>>>> 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)
    >>>>>> for
    >>>>>> those releases. Some guests may rely on a specific version and may 
now
    >>>>>> crashes.
    >>>>>>
    >>>>>> Overall, the right way to support spectre in earlier releases is
    >>>>>> custom patch
    >>>>>> and only do minimal modification.
    >>>>>>
    >>>>>>> git://xenbits.xen.org/people/sstabellini/xen-unstable.git
    >>>>>>> staging-4.10-spectre
    >>>>>>
    >>>>>> The patches below should not be part of spectre nor backport to 4.10:
    >>>>>>     - 82e29c87dc7f4f2a7e2f111c3646479da21a910a "ARM: remove unneeded
    >>>>>> gic.h
    >>>>>> inclusions"
    >>>>>>     - 79563717c9dd5383abcf0ba94d813de9b42e3793 "xen/arm: psci: Prefix
    >>>>>> with
    >>>>>> static any functions not exported"
    >>>>>>     - 6d0e9b21b1f7213c1994cc2d636448ee2d5372c2 "xen/arm: vpsci: 
Update
    >>>>>> the
    >>>>>> 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
    >>>>>> ARM_SMCCC_ARCH_WORKAROUND_1.
    >>>>>
    >>>>> 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.
    
    Cheers,
    
    -- 
    Julien Grall
    

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