This is a note to let you know that I've just added the patch titled
x86/xen: Zero MSR_IA32_SPEC_CTRL before suspend
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-xen-zero-msr_ia32_spec_ctrl-before-suspend.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 71c208dd54ab971036d83ff6d9837bae4976e623 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@xxxxxxxx>
Date: Mon, 26 Feb 2018 15:08:18 +0100
Subject: x86/xen: Zero MSR_IA32_SPEC_CTRL before suspend
From: Juergen Gross <jgross@xxxxxxxx>
commit 71c208dd54ab971036d83ff6d9837bae4976e623 upstream.
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@xxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Cc: boris.ostrovsky@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20180226140818.4849-1-jgross@xxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/xen/suspend.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -1,11 +1,14 @@
#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>
@@ -68,6 +71,8 @@ static void xen_pv_post_suspend(int susp
xen_mm_unpin_all();
}
+static DEFINE_PER_CPU(u64, spec_ctrl);
+
void xen_arch_pre_suspend(void)
{
if (xen_pv_domain())
@@ -84,6 +89,9 @@ 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;
@@ -93,7 +101,15 @@ static void xen_vcpu_notify_restore(void
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)
Patches currently in stable-queue which might be from jgross@xxxxxxxx are
queue-4.4/x86-xen-zero-msr_ia32_spec_ctrl-before-suspend.patch