Re: [Xen-devel] [PATCH 0/7] xen/arm: PSCI 1.1 and SMCCC-1.1 support and XSA-254 variant 2 update

[Manish Jaggi <mjaggi@xxxxxxxxxxxxxxxxxx>]

Hi Julien,


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.
> [2]: https://github.com/ARM-software/arm-trusted-firmware/pull/1240
>
> [3] https://lists.xenproject.org/archives/html/xen-devel/2018-02/msg00117.html
>
> Julien Grall (7):
>    xen/arm: vpsci: Remove parameter 'ver' from do_common_cpu
>    xen/arm: psci: Rework the PSCI definitions
>    xen/arm: vpsci: Add support for PSCI 1.1
>    xen/arm: vsmc: Implement SMCCC 1.1
>    xen/arm: vsmc: Implement SMCCC_ARCH_WORKAROUND_1 BP hardening support
>    xen/arm: Adapt smccc.h to be able to use it in assembly code
>    xen/arm64: Implement a fast path for handling SMCCC_ARCH_WORKAROUND_1
>
>   tools/libxl/libxl_arm.c          |  3 +-
>   xen/arch/arm/arm64/entry.S       | 56 +++++++++++++++++++++++++-
>   xen/arch/arm/domain_build.c      |  1 +
>   xen/arch/arm/platforms/seattle.c |  4 +-
>   xen/arch/arm/psci.c              | 10 ++---
>   xen/arch/arm/vpsci.c             | 85 +++++++++++++++++++++++++++++-----------
>   xen/arch/arm/vsmc.c              | 41 +++++++++++++++++++
>   xen/include/asm-arm/perfc_defn.h |  1 +
>   xen/include/asm-arm/processor.h  |  2 +
>   xen/include/asm-arm/psci.h       | 38 ++++++++++--------
>   xen/include/asm-arm/smccc.h      | 37 ++++++++++++++---
>   xen/include/asm-arm/vpsci.h      |  2 +-
>   12 files changed, 225 insertions(+), 55 deletions(-)

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