Re: [Xen-devel] [PATCH] xen/arm: Relax ARM_SMCCC_ARCH_WORKAROUND_1 discovery

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 03/16/2018 08:27 PM, Stefano Stabellini wrote:
> On Mon, 12 Mar 2018, julien.grall@xxxxxxx wrote:
> > From: Julien Grall <julien.grall@xxxxxxx>
> >
> > A recent update to the ARM SMCCC_ARCH_WORKAROUND_1 specification (see [1])
> > allows firmware to return a non zero, positive value, to describe that
> > although the mitigation is implemented at the higher exception level,
> > the CPU on which the call is made is not affected.
> >
> > Relax the check on the return value from ARM_WORKAROUND_1 so that we
> > only error out if the returned value is negative.
> >
> > [1] https://developer.arm.com/support/security-update/downloads
> > "Firmware interfaces for mitigating CVE-2017-5715 System Software on Arm
> > Systems"
> >
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>
> > ---
> >      This patch should be backported as part of XSA-254.
> >
> >      There are potential more optimization to do as part of this
> >      relaxation. For instance, we dropping the CPU ID recognition and
> >      only look ad the SMCCC.
> Indeed there are. I assume more patches will be coming?
It is not in my immediate plan. I pointed out if someone wants to 
implement and send a patch.
Cheers,

--
Julien Grall

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