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Roger Pau Monné
1932973ac9
Introduce a new Kconfig option to block speculation into lock protected
critical regions. The Kconfig option is enabled by default, but the mitigation
won't be engaged unless it's explicitly enabled in the command line using
`spec-ctrl=lock-harden`.
Convert the spinlock acquire macros into always-inline functions, and introduce
a speculation barrier after the lock has been taken. Note the speculation
barrier is not placed inside the implementation of the spin lock functions, as
to prevent speculation from falling through the call to the lock functions
resulting in the barrier also being skipped.
trylock variants are protected using a construct akin to the existing
evaluate_nospec().
This patch only implements the speculation barrier for x86.
Note spin locks are the only locking primitive taken care in this change,
further locking primitives will be adjusted by separate changes.
This is part of XSA-453 / CVE-2024-2193
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 7ef0084418)