'idle' here refers to hlt/mwait. The S3 path isn't an idle path - it is a
platform reset.
Conditionally clearing IBRS and flushing the store buffers on the way down is
a waste of time.
Furthermore, we want to load default_xen_mcu_opt_ctrl unilaterally on the way
back up. Currently it happens as a side effect of X86_FEATURE_SC_MSR_IDLE or
the next return-to-guest, but that's fragile behaviour.
Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
---
CC: Jan Beulich <jbeul...@suse.com>
CC: Roger Pau Monné <roger....@citrix.com>
CC: Wei Liu <w...@xen.org>
v2:
* New
---
xen/arch/x86/acpi/power.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/xen/arch/x86/acpi/power.c b/xen/arch/x86/acpi/power.c
index 31a56f02d083..ea2bd8bbfe93 100644
--- a/xen/arch/x86/acpi/power.c
+++ b/xen/arch/x86/acpi/power.c
@@ -248,7 +248,6 @@ static int enter_state(u32 state)
error = 0;
ci = get_cpu_info();
- spec_ctrl_enter_idle(ci);
/* Avoid NMI/#MC using MSR_SPEC_CTRL until we've reloaded microcode. */
ci->spec_ctrl_flags &= ~SCF_ist_wrmsr;
@@ -295,7 +294,9 @@ static int enter_state(u32 state)
/* Re-enabled default NMI/#MC use of MSR_SPEC_CTRL. */
ci->spec_ctrl_flags |= (default_spec_ctrl_flags & SCF_ist_wrmsr);
- spec_ctrl_exit_idle(ci);
+
+ if ( boot_cpu_has(X86_FEATURE_IBRSB) )
+ wrmsrl(MSR_SPEC_CTRL, default_xen_mcu_opt_ctrl);
if ( boot_cpu_has(X86_FEATURE_SRBDS_CTRL) )
wrmsrl(MSR_MCU_OPT_CTRL, default_xen_mcu_opt_ctrl);
--
2.11.0
