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x86/xen: Zero MSR_IA32_SPEC_CTRL before suspend

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Older Xen versions (4.5 and before) might have problems migrating pv
guests with MSR_IA32_SPEC_CTRL having a non-zero value. So before
suspending zero that MSR and restore it after being resumed.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Cc: stable@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Cc: boris.ostrovsky@oracle.com
Link: https://lkml.kernel.org/r/20180226140818.4849-1-jgross@suse.com
This commit is contained in:
Juergen Gross 2018-02-26 15:08:18 +01:00 committed by Thomas Gleixner
parent 946fbbc13d
commit 71c208dd54
1 changed files with 16 additions and 0 deletions
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16
arch/x86/xen/suspend.c
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@ -1,12 +1,15 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/types.h>
#include <linux/tick.h>
#include <linux/percpu-defs.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
#include <xen/grant_table.h>
#include <xen/events.h>
#include <asm/cpufeatures.h>
#include <asm/msr-index.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/page.h>
#include <asm/fixmap.h>
@ -15,6 +18,8 @@
#include "mmu.h"
#include "pmu.h"
static DEFINE_PER_CPU(u64, spec_ctrl);
void xen_arch_pre_suspend(void)
{
xen_save_time_memory_area();
@ -35,6 +40,9 @@ void xen_arch_post_suspend(int cancelled)
static void xen_vcpu_notify_restore(void *data)
{
if (xen_pv_domain() && boot_cpu_has(X86_FEATURE_SPEC_CTRL))
wrmsrl(MSR_IA32_SPEC_CTRL, this_cpu_read(spec_ctrl));
/* Boot processor notified via generic timekeeping_resume() */
if (smp_processor_id() == 0)
return;
@ -44,7 +52,15 @@ static void xen_vcpu_notify_restore(void *data)
static void xen_vcpu_notify_suspend(void *data)
{
u64 tmp;
tick_suspend_local();
if (xen_pv_domain() && boot_cpu_has(X86_FEATURE_SPEC_CTRL)) {
rdmsrl(MSR_IA32_SPEC_CTRL, tmp);
this_cpu_write(spec_ctrl, tmp);
wrmsrl(MSR_IA32_SPEC_CTRL, 0);
}
}
void xen_arch_resume(void)