On 08/02/18 16:26, Manish Jaggi wrote:
On 02/05/2018 06:50 PM, Julien Grall wrote:
Hi all,

Arm has recently published a SMC Calling Convention (SMCCC)
specification update [1] that provides an optimised calling convention
and optional, discoverable support for mitigating CVE-2017-5715 (XSA-254
variant 2). ARM Trusted Firmware (ATF) has already gained such an
implementation[2].

This series addresses a few things:

     - It provides a Xen implementation of PSCI v1.0, which is a prerequisite
       for being able to discover SMCCC v1.1.
     - It allows Xen to advertise SMCCC v1.1
     - It implements Xen support for the ARM_WORKAROUND_1 function that is used
       to mitigate CVE-2017-5715 (if such mitigation is available on the
       hypervisor).

This method is intended to fully replace the initial PSCI_GET_VERSION
approach. Although PSCI_GET_VERSION still works, it has an obvious
overhead and is called on some of the hottest paths. We expect
ARCH_WORKAROUND_1 to be much faster.

Another series will be sent to allow the hypervisor discovering SMCCC 1.1 and
use it for the mitigation.

This series is based on the "xen/arm: SMCCC fixes and PSCI clean-up" one [3].

Cheers,

[1]: https://developer.arm.com/-/media/developer/pdf/ARM%20DEN%200070A%20Firmware%20interfaces%20for%20mitigating%20CVE-2017-5715_V1.0.pdf
This link is not working.

Because the link has been relocated since then. You can find it at:

https://developer.arm.com/support/security-update/downloads

Cheers,

--
Julien Grall

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