x86: Use xen_vcpuop_clockevent, xen_clocksource and xen wallclock.

Use xen_vcpuop_clockevent instead of hpet and APIC timers as main
clockevent device on all vcpus, use the xen wallclock time as wallclock
instead of rtc and use xen_clocksource as clocksource.
The pv clock algorithm needs to work correctly for the xen_clocksource
and xen wallclock to be usable, only modern Xen versions offer a
reliable pv clock in HVM guests (XENFEAT_hvm_safe_pvclock).

Using the hpet as clocksource means a VMEXIT every time we read/write to
the hpet mmio addresses, pvclock give us a better rating without
VMEXITs. Same goes for the xen wallclock and xen_vcpuop_clockevent

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Don Dutile <ddutile@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

1 files changed, 2 insertions, 12 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 127c95c8d15e..a90172963884 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -935,10 +935,6 @@ static const struct pv_init_ops xen_init_ops __initdata = {
         .patch = xen_patch,
 };
 
-static const struct pv_time_ops xen_time_ops __initdata = {
-        .sched_clock = xen_sched_clock,
-};
-
 static const struct pv_cpu_ops xen_cpu_ops __initdata = {
         .cpuid = xen_cpuid,
 
@@ -1076,7 +1072,6 @@ asmlinkage void __init xen_start_kernel(void)
         /* Install Xen paravirt ops */
         pv_info = xen_info;
         pv_init_ops = xen_init_ops;
-        pv_time_ops = xen_time_ops;
         pv_cpu_ops = xen_cpu_ops;
         pv_apic_ops = xen_apic_ops;
 
@@ -1084,13 +1079,7 @@ asmlinkage void __init xen_start_kernel(void)
         x86_init.oem.arch_setup = xen_arch_setup;
         x86_init.oem.banner = xen_banner;
 
-        x86_init.timers.timer_init = xen_time_init;
-        x86_init.timers.setup_percpu_clockev = x86_init_noop;
-        x86_cpuinit.setup_percpu_clockev = x86_init_noop;
-
-        x86_platform.calibrate_tsc = xen_tsc_khz;
-        x86_platform.get_wallclock = xen_get_wallclock;
-        x86_platform.set_wallclock = xen_set_wallclock;
+        xen_init_time_ops();
 
         /*
          * Set up some pagetable state before starting to set any ptes.
@@ -1327,6 +1316,7 @@ static void __init xen_hvm_guest_init(void)
         register_cpu_notifier(&xen_hvm_cpu_notifier);
         have_vcpu_info_placement = 0;
         x86_init.irqs.intr_init = xen_init_IRQ;
+        xen_hvm_init_time_ops();
 }
 
 static bool __init xen_hvm_platform(void)