From: Juergen Gross jgross@suse.com

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@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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Srivatsa S. Bhat srivatsa@csail.mit.edu Reviewed-by: Matt Helsley (VMware) matt.helsley@gmail.com Reviewed-by: Alexey Makhalov amakhalov@vmware.com Reviewed-by: Bo Gan ganb@vmware.com ---

arch/x86/xen/suspend.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)

diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c index 7f664c4..4ecd0de 100644 --- 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 suspend_cancelled) 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 *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)