From: Andrew Cooper Date: Fri, 28 Jan 2022 12:03:42 +0000 (+0000) Subject: x86/spec-ctrl: Don't use spec_ctrl_{enter,exit}_idle() for S3 X-Git-Tag: archive/raspbian/4.16.0+51-g0941d6cb-1+rpi1~2^2~26^2~18 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=72ef02da23861f686c349a6808b2f4c9adc15f9f;p=xen.git x86/spec-ctrl: Don't use spec_ctrl_{enter,exit}_idle() for S3 'idle' here refers to hlt/mwait. The S3 path isn't an idle path - it is a platform reset. We need to load default_xen_spec_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. Conversely, there is no need to clear IBRS and flush the store buffers on the way down; we're microseconds away from cutting power. Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich (cherry picked from commit 71fac402e05ade7b0af2c34f77517449f6f7e2c1) --- diff --git a/xen/arch/x86/acpi/power.c b/xen/arch/x86/acpi/power.c index 31a56f02d0..0837a3ead4 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_spec_ctrl); if ( boot_cpu_has(X86_FEATURE_SRBDS_CTRL) ) wrmsrl(MSR_MCU_OPT_CTRL, default_xen_mcu_opt_ctrl);