## Copyright (C) 2019 - 2023 ENCRYPTED SUPPORT LP <adrelanos@whonix.org>
## See the file COPYING for copying conditions.

## Enables all known mitigations for CPU vulnerabilities.
##
## https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/index.html
## https://forums.whonix.org/t/should-all-kernel-patches-for-cpu-bugs-be-unconditionally-enabled-vs-performance-vs-applicability/7647

## Enable mitigations for Spectre variant 2 (indirect branch speculation).
##
## https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/spectre.html
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX spectre_v2=on"

## Disable Speculative Store Bypass.
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX spec_store_bypass_disable=on"

## Enable mitigations for the L1TF vulnerability through disabling SMT
## and L1D flush runtime control.
##
## https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX l1tf=full,force"

## Enable mitigations for the MDS vulnerability through clearing buffer cache
## and disabling SMT.
##
## https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX mds=full,nosmt"

## Patches the TAA vulnerability by disabling TSX and enables mitigations using
## TSX Async Abort along with disabling SMT.
##
## https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX tsx=off tsx_async_abort=full,nosmt"

## Mark all huge pages in the EPT as non-executable to mitigate iTLB multihit.
##
## https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/multihit.html
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX kvm.nx_huge_pages=force"

## Enables mitigations for SRBDS to prevent MDS attacks on RDRAND and RDSEED instructions.
## Only mitigated through microcode updates from Intel.
##
## https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/special-register-buffer-data-sampling.html
## https://access.redhat.com/solutions/5142691

## Force disable SMT as it has caused numerous CPU vulnerabilities.
## The only full mitigation of cross-HT attacks is to disable SMT.
##
## https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/core-scheduling.html
## https://forums.whonix.org/t/should-all-kernel-patches-for-cpu-bugs-be-unconditionally-enabled-vs-performance-vs-applicability/7647/17
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX nosmt=force"

## Enables the prctl interface to prevent leaks from L1D on context switches.
##
## https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1d_flush.html
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX l1d_flush=on"

## Mitigates numerous MMIO Stale Data vulnerabilities and disables SMT.
##
## https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.html
GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX mmio_stale_data=full,nosmt"