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From 62bd851a4469976f036c2d804ebed7ca39741254 Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Fri, 18 May 2018 11:53:13 +0200
Subject: [PATCH] x86: suppress BTI mitigations around S3 suspend/resume
NMI and #MC can occur at any time after S3 resume, yet the MSR_SPEC_CTRL
may become available only once we're reloaded microcode. Make
SPEC_CTRL_ENTRY_FROM_INTR_IST and DO_SPEC_CTRL_EXIT_TO_XEN no-ops for
the critical period of time.
Also set the MSR back to its intended value.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
x86: Use spec_ctrl_{enter,exit}_idle() in the S3/S5 path
The main purpose of this patch is to avoid opencoding the recovery logic at
the end, but also has the positive side effect of relaxing the SPEC_CTRL
mitigations when working to shut the final CPU down.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 710a8ebf2bc111a34bba04d1c85b6d07ed3d9389
master date: 2018-04-16 14:09:55 +0200
master commit: ef3ab46493f650b7e5cca2b2578a99ca0cbff195
master date: 2018-04-19 10:55:59 +0100
---
xen/arch/x86/acpi/power.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/xen/arch/x86/acpi/power.c b/xen/arch/x86/acpi/power.c
index cb06f842cd..f7085d3c7b 100644
--- a/xen/arch/x86/acpi/power.c
+++ b/xen/arch/x86/acpi/power.c
@@ -28,6 +28,7 @@
#include <asm/tboot.h>
#include <asm/apic.h>
#include <asm/io_apic.h>
+#include <asm/spec_ctrl.h>
#include <acpi/cpufreq/cpufreq.h>
uint32_t system_reset_counter = 1;
@@ -163,6 +164,7 @@ static int enter_state(u32 state)
{
unsigned long flags;
int error;
+ struct cpu_info *ci;
unsigned long cr4;
if ( (state <= ACPI_STATE_S0) || (state > ACPI_S_STATES_MAX) )
@@ -210,6 +212,11 @@ static int enter_state(u32 state)
else
error = 0;
+ ci = get_cpu_info();
+ spec_ctrl_enter_idle(ci);
+ /* Avoid NMI/#MC using MSR_SPEC_CTRL until we've reloaded microcode. */
+ ci->bti_ist_info = 0;
+
ACPI_FLUSH_CPU_CACHE();
switch ( state )
@@ -248,6 +255,10 @@ static int enter_state(u32 state)
microcode_resume_cpu(0);
+ /* Re-enabled default NMI/#MC use of MSR_SPEC_CTRL. */
+ ci->bti_ist_info = default_bti_ist_info;
+ spec_ctrl_exit_idle(ci);
+
done:
spin_debug_enable();
local_irq_restore(flags);
--
2.15.2
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