[U-Boot] [PATCH 0/4] ARM: Provide workaround setup bits for CVE-2017-5715 (A8/A15)

[Tom Rini]

On Tue, Jun 12, 2018 at 03:24:07PM -0500, Nishanth Menon wrote:

> Hi,
> 
> This is a follow on from https://marc.info/?l=u-boot&m=151691688828176&w=2 (RFC)
> 
> NOTE:
> * As per ARM recommendations[2], and discussions in list[1] ARM
>   Cortex-A9/12/17 do not need additional steps in u-boot to enable the
>   OS level workarounds.
> * This itself is'nt a complete solution and is based on recommendation
>   This from Arm[2] for variant 2 CVE-2017-5715 -> Kernel changes can be seen on
>   linux next (next-20180612) or on linux master (upcoming v4.18-rc1 tag).
> * I think it is necessary on older SoCs without firmware support
>   (such as older OMAPs and AM*) to have kernel support mirroring what we do in
>   u-boot to support additional cores AND/OR low power states where contexts are
>   lost (assuming ACR states are'nt saved). just my 2 cents.
> 
> Few of the tests (with linux next-20180612):
> AM571-IDK: https://pastebin.ubuntu.com/p/sr5X6sN3Tr/ (single core A15)
> OMAP5-uEVM: https://pastebin.ubuntu.com/p/9yDM22bJ6n/ (dual core A15)
> OMAP3-beagle-xm: https://pastebin.ubuntu.com/p/9DfDkpyxym/ (Single A8)
> AM335x-Beaglebone-black: https://pastebin.ubuntu.com/p/DczT9jPMwb/ (Single A8)
> 
> Nishanth Menon (4):
>   ARM: Introduce ability to enable ACR::IBE on Cortex-A8 for
>     CVE-2017-5715
>   ARM: Introduce ability to enable invalidate of BTB with ICIALLU on
>     Cortex-A15 for CVE-2017-5715
>   ARM: mach-omap2: omap5/dra7: Enable ACTLR[0] (Enable invalidates of
>     BTB) to facilitate CVE_2017-5715 WA in OS
>   ARM: mach-omap2: omap3/am335x: Enable ACR::IBE on Cortex-A8 SoCs for
>     CVE-2017-5715
> 
>  arch/arm/Kconfig            |  9 +++++++++
>  arch/arm/cpu/armv7/start.S  | 15 +++++++++++++--
>  arch/arm/mach-omap2/Kconfig |  3 +++
>  3 files changed, 25 insertions(+), 2 deletions(-)
> 
> [1] https://marc.info/?t=151639906500002&r=1&w=2
> [2] https://developer.arm.com/support/security-update
> [3] https://marc.info/?t=151543790400007&r=1&w=2 and the latest in:
> 	https://marc.info/?l=linux-arm-kernel&m=151689379521082&w=2
> [4]
> 	https://github.com/ARM-software/arm-trusted-firmware/wiki/ARM-Trusted-Firmware-Security-Advisory-TFV-6
> 	https://www.op-tee.org/security-advisories/
> 	https://www.linaro.org/blog/meltdown-spectre/

This series of changes for U-Boot, if I can briefly summarize the
feedback as I understand it, is that yes, this is correct and is a part
of what is required to work around the issues, but only covers as much
of the system as U-Boot can cover leaving other parts of the software
stack (still) in need of fixes.  Yes?  If so, is there anything else
that should be done before in U-Boot we grab these changes?  Would any
of the knowledgeable but not usually U-Boot folks on CC feel comfortable
adding an ack/reviewed-by to the series?  Thanks!

-- 
Tom
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