x86/spec-ctrl: Clean up MSR_MCU_OPT_CTRL handling
Introduce cpu_has_srbds_ctrl as more users are going to appear shortly.
MSR_MCU_OPT_CTRL is gaining extra functionality, meaning that the current
default_xen_mcu_opt_ctrl is no longer a good fit.
Introduce two new helpers, update_mcu_opt_ctrl() which does a full RMW cycle
on the MSR, and set_in_mcu_opt_ctrl() which lets callers configure specific
bits at a time without clobbering each others settings.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit
39a40f3835efcc25c1b05a25c321a01d7e11cbd7)
projects / xen.git / commit