diff options
| author | Andrew Cooper <andrew.cooper3@citrix.com> | 2022-01-25 16:09:59 +0000 |
|---|---|---|
| committer | Andrew Cooper <andrew.cooper3@citrix.com> | 2022-02-04 15:45:25 +0000 |
| commit | 7f34b6a895d10744bab32fc843246c45da444d8b (patch) | |
| tree | 1de1124fd16374dffdd1dff228297565be30ebfc | |
| parent | df2e2952b8c8087988f240a08a9417aa503cbd1c (diff) | |
x86/spec-ctrl: Drop use_spec_ctrl boolean
Several bugfixes have reduced the utility of this variable from it's original
purpose, and now all it does is aid in the setup of SCF_ist_wrmsr.
Simplify the logic by drop the variable, and doubling up the setting of
SCF_ist_wrmsr for the PV and HVM blocks, which will make the AMD SPEC_CTRL
support easier to follow. Leave a comment explaining why SCF_ist_wrmsr is
still necessary for the VMExit case.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit ec083bf552c35e10347449e21809f4780f8155d2)
| -rw-r--r-- | xen/arch/x86/spec_ctrl.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c index c18cc8aa49..8a550d0a09 100644 --- a/xen/arch/x86/spec_ctrl.c +++ b/xen/arch/x86/spec_ctrl.c @@ -927,7 +927,7 @@ static __init void mds_calculations(uint64_t caps) void __init init_speculation_mitigations(void) { enum ind_thunk thunk = THUNK_DEFAULT; - bool use_spec_ctrl = false, ibrs = false, hw_smt_enabled; + bool ibrs = false, hw_smt_enabled; bool cpu_has_bug_taa; uint64_t caps = 0; @@ -1016,19 +1016,21 @@ void __init init_speculation_mitigations(void) { if ( opt_msr_sc_pv ) { - use_spec_ctrl = true; + default_spec_ctrl_flags |= SCF_ist_wrmsr; setup_force_cpu_cap(X86_FEATURE_SC_MSR_PV); } if ( opt_msr_sc_hvm ) { - use_spec_ctrl = true; + /* + * While the guest MSR_SPEC_CTRL value is loaded/saved atomically, + * Xen's value is not restored atomically. An early NMI hitting + * the VMExit path needs to restore Xen's value for safety. + */ + default_spec_ctrl_flags |= SCF_ist_wrmsr; setup_force_cpu_cap(X86_FEATURE_SC_MSR_HVM); } - if ( use_spec_ctrl ) - default_spec_ctrl_flags |= SCF_ist_wrmsr; - if ( ibrs ) default_xen_spec_ctrl |= SPEC_CTRL_IBRS; } |