3.16.57-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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: xen-devel@xxxxxxxxxxxxxxxxxxxx Cc: boris.ostrovsky@xxxxxxxxxx Link: https://lkml.kernel.org/r/20180226140818.4849-1-jgross@xxxxxxxx [bwh: Backported to 3.16: - Include <asm/cpufeature.h> instead of <asm/cpufeatures.h> - Adjust context] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- --- a/arch/x86/xen/suspend.c +++ b/arch/x86/xen/suspend.c @@ -1,10 +1,13 @@ #include <linux/types.h> #include <linux/clockchips.h> +#include <linux/percpu-defs.h> #include <xen/interface/xen.h> #include <xen/grant_table.h> #include <xen/events.h> +#include <asm/cpufeature.h> +#include <asm/msr-index.h> #include <asm/xen/hypercall.h> #include <asm/xen/page.h> #include <asm/fixmap.h> @@ -12,6 +15,8 @@ #include "xen-ops.h" #include "mmu.h" +static DEFINE_PER_CPU(u64, spec_ctrl); + static void xen_pv_pre_suspend(void) { xen_mm_pin_all(); @@ -84,6 +89,9 @@ static void xen_vcpu_notify_restore(void { unsigned long reason = (unsigned long)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; @@ -93,6 +101,13 @@ static void xen_vcpu_notify_restore(void static void xen_vcpu_notify_suspend(void *data) { + u64 tmp; + + 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)
