I forgot to CC Juergen as RM. This series is candidate for Xen 4.11 as
part of XSA-263.
Cheers,
On 22/05/18 18:42, Julien Grall wrote:
Hi all,
This patch series implement the Xen hypervisor side of the "Spectre-v4"
(CVE-2018-3639) mitigation known as "Speculative Store Bypass Disable"
(SSBD).
More information can be found at:
https://bugs.chromium.org/p/project-zero/issues/detail?id=1528
https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability
For all released Arm Cortex-A that are affected by this issue, then the
preferred mitigation is simply to set a chicken bit in the firmware during
CPU initialization and therefore no change to Xen is required. Other CPUs
may require the chicken bit to be toggled dynamically (for example, when
switching between kernel-mode and hypervisor-mode) and this is achieve by
calling into EL3 via an SMC which has been published as part of the latest
SMCCC specification:
https://developer.arm.com/cache-speculation-vulnerability-firmware-specification
as well as an ATF update for the released ARM cores affected by SSBD:
https://github.com/ARM-software/arm-trusted-firmware/pull/1392
These patches provide the following:
1. Safe probing of firmware to establish which CPUs in the system
require calling into EL3 as part of the mitigation
2. A command-line option to force SSBD mitigation to be always on,
always off, or dynamically toggled (default) for CPUs that require
the EL3 call.
3. An initial implementation of the call via Xen, which exposes the
mitigation to the guest via an HVC interface.
This patch also provides bug fix and new infrastructure require to implement
the mitigation:
1. Zeroed each vCPU stack
2. Provide generic assembly macros
3. Provide alternative callback (RFC)
A branch can be found with all the patches at:
https://xenbits.xen.org/git-http/people/julieng/xen-unstable.git
branch ssbd/v1
Cheers,
Julien Grall (13):
xen/arm: domain: Zeroed the vCPU stack
xen/arm64: entry: Use named label in guest_sync
xen/arm: setup: Check errata for boot CPU later on
xen/arm: Add ARCH_WORKAROUND_2 probing
xen/arm: Add command line option to control SSBD mitigation
xen/arm: Add ARCH_WORKAROUND_2 support for guests
xen/arm: Simplify alternative patching
xen/arm: alternatives: Add dynamic patching feature
xen/arm64: Add generic assembly macros
xen/arm64: Implement a fast path for handling SMCCC_ARCH_WORKAROUND_2
xen/arm: Kconfig: Move HARDEN_BRANCH_PREDICTOR under "Architecture
features"
xen/arm: smccc: Fix indentation in ARM_SMCCC_ARCH_WORKAROUND_1_FID
xen/arm: Avoid to use current everywhere in enter_hypervisor_head
docs/misc/xen-command-line.markdown | 18 +++++
xen/arch/arm/Kconfig | 44 +++++++----
xen/arch/arm/alternative.c | 79 +++++++++++--------
xen/arch/arm/arm64/asm-offsets.c | 2 +
xen/arch/arm/arm64/entry.S | 49 +++++++++++-
xen/arch/arm/cpuerrata.c | 150 ++++++++++++++++++++++++++++++++++++
xen/arch/arm/domain.c | 12 +++
xen/arch/arm/setup.c | 8 +-
xen/arch/arm/traps.c | 32 ++++++--
xen/arch/arm/vsmc.c | 37 +++++++++
xen/include/asm-arm/alternative.h | 44 +++++++++--
xen/include/asm-arm/arm64/macros.h | 25 ++++++
xen/include/asm-arm/cpuerrata.h | 42 ++++++++++
xen/include/asm-arm/cpufeature.h | 3 +-
xen/include/asm-arm/current.h | 6 +-
xen/include/asm-arm/macros.h | 2 +-
xen/include/asm-arm/smccc.h | 13 +++-
17 files changed, 495 insertions(+), 71 deletions(-)
create mode 100644 xen/include/asm-arm/arm64/macros.h
--
Julien Grall
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