add dts config

hc

2023-12-06 08f87f769b595151be1afeff53e144f543faa614

 kernel/arch/x86/xen/time.c
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@@ -28,7 +28,7 @@
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 #include "xen-ops.h"
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-/* Xen may fire a timer up to this many ns early */
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+/* Minimum amount of time until next clock event fires */
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 #define TIMER_SLOP	100000
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 static u64 xen_sched_clock_offset __read_mostly;
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@@ -39,6 +39,7 @@
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 	struct pvclock_vcpu_time_info *info =
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 		&HYPERVISOR_shared_info->vcpu_info[0].time;
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+	setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
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 	return pvclock_tsc_khz(info);
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 }
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@@ -145,12 +146,19 @@
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 	.notifier_call = xen_pvclock_gtod_notify,
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 };
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+static int xen_cs_enable(struct clocksource *cs)
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+{
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+	vclocks_set_used(VDSO_CLOCKMODE_PVCLOCK);
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+	return 0;
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+}
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+
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 static struct clocksource xen_clocksource __read_mostly = {
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-	.name = "xen",
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-	.rating = 400,
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-	.read = xen_clocksource_get_cycles,
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-	.mask = ~0,
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-	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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+	.name	= "xen",
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+	.rating	= 400,
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+	.read	= xen_clocksource_get_cycles,
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+	.mask	= CLOCKSOURCE_MASK(64),
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+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
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+	.enable = xen_cs_enable,
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 };
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 /*
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@@ -212,7 +220,7 @@
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 	return 0;
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 }
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-static const struct clock_event_device xen_timerop_clockevent = {
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+static struct clock_event_device xen_timerop_clockevent __ro_after_init = {
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 	.name			= "xen",
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 	.features		= CLOCK_EVT_FEAT_ONESHOT,
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@@ -273,7 +281,7 @@
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 	return ret;
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 }
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-static const struct clock_event_device xen_vcpuop_clockevent = {
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+static struct clock_event_device xen_vcpuop_clockevent __ro_after_init = {
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 	.name = "xen",
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 	.features = CLOCK_EVT_FEAT_ONESHOT,
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@@ -412,12 +420,13 @@
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 	ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
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421
 
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 	/*
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-	 * We don't disable VCLOCK_PVCLOCK entirely if it fails to register the
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-	 * secondary time info with Xen or if we migrated to a host without the
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-	 * necessary flags. On both of these cases what happens is either
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-	 * process seeing a zeroed out pvti or seeing no PVCLOCK_TSC_STABLE_BIT
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-	 * bit set. Userspace checks the latter and if 0, it discards the data
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-	 * in pvti and fallbacks to a system call for a reliable timestamp.
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+	 * We don't disable VDSO_CLOCKMODE_PVCLOCK entirely if it fails to
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+	 * register the secondary time info with Xen or if we migrated to a
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+	 * host without the necessary flags. On both of these cases what
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+	 * happens is either process seeing a zeroed out pvti or seeing no
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+	 * PVCLOCK_TSC_STABLE_BIT bit set. Userspace checks the latter and
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+	 * if 0, it discards the data in pvti and fallbacks to a system
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+	 * call for a reliable timestamp.
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 	 */
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 	if (ret != 0)
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 		pr_notice("Cannot restore secondary vcpu_time_info (err %d)",
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@@ -443,7 +452,7 @@
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 	ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
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 	if (ret) {
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-		pr_notice("xen: VCLOCK_PVCLOCK not supported (err %d)\n", ret);
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+		pr_notice("xen: VDSO_CLOCKMODE_PVCLOCK not supported (err %d)\n", ret);
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 		free_page((unsigned long)ti);
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 		return;
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 	}
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@@ -460,14 +469,14 @@
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 		if (!ret)
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 			free_page((unsigned long)ti);
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-		pr_notice("xen: VCLOCK_PVCLOCK not supported (tsc unstable)\n");
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+		pr_notice("xen: VDSO_CLOCKMODE_PVCLOCK not supported (tsc unstable)\n");
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 		return;
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 	}
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 	xen_clock = ti;
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 	pvclock_set_pvti_cpu0_va(xen_clock);
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-	xen_clocksource.archdata.vclock_mode = VCLOCK_PVCLOCK;
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+	xen_clocksource.vdso_clock_mode = VDSO_CLOCKMODE_PVCLOCK;
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 }
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 static void __init xen_time_init(void)
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@@ -519,7 +528,7 @@
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 void __init xen_init_time_ops(void)
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 {
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 	xen_sched_clock_offset = xen_clocksource_read();
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-	pv_time_ops = xen_time_ops;
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+	pv_ops.time = xen_time_ops;
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 	x86_init.timers.timer_init = xen_time_init;
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 	x86_init.timers.setup_percpu_clockev = x86_init_noop;
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@@ -547,6 +556,11 @@
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 void __init xen_hvm_init_time_ops(void)
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 {
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+	static bool hvm_time_initialized;
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+
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+	if (hvm_time_initialized)
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+		return;
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+
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 	/*
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 	 * vector callback is needed otherwise we cannot receive interrupts
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 	 * on cpu > 0 and at this point we don't know how many cpus are
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@@ -556,17 +570,48 @@
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 		return;
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 	if (!xen_feature(XENFEAT_hvm_safe_pvclock)) {
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-		pr_info("Xen doesn't support pvclock on HVM, disable pv timer");
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+		pr_info_once("Xen doesn't support pvclock on HVM, disable pv timer");
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+		return;
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+	}
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+
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+	/*
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+	 * Only MAX_VIRT_CPUS 'vcpu_info' are embedded inside 'shared_info'.
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+	 * The __this_cpu_read(xen_vcpu) is still NULL when Xen HVM guest
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+	 * boots on vcpu >= MAX_VIRT_CPUS (e.g., kexec), To access
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+	 * __this_cpu_read(xen_vcpu) via xen_clocksource_read() will panic.
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+	 *
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+	 * The xen_hvm_init_time_ops() should be called again later after
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+	 * __this_cpu_read(xen_vcpu) is available.
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+	 */
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+	if (!__this_cpu_read(xen_vcpu)) {
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+		pr_info("Delay xen_init_time_common() as kernel is running on vcpu=%d\n",
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+			xen_vcpu_nr(0));
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 		return;
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 	}
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 	xen_sched_clock_offset = xen_clocksource_read();
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-	pv_time_ops = xen_time_ops;
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+	pv_ops.time = xen_time_ops;
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 	x86_init.timers.setup_percpu_clockev = xen_time_init;
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 	x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;
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 	x86_platform.calibrate_tsc = xen_tsc_khz;
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 	x86_platform.get_wallclock = xen_get_wallclock;
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 	x86_platform.set_wallclock = xen_set_wallclock;
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+
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+	hvm_time_initialized = true;
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 }
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 #endif
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+
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+/* Kernel parameter to specify Xen timer slop */
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+static int __init parse_xen_timer_slop(char *ptr)
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+{
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+	unsigned long slop = memparse(ptr, NULL);
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+
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+	xen_timerop_clockevent.min_delta_ns = slop;
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+	xen_timerop_clockevent.min_delta_ticks = slop;
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+	xen_vcpuop_clockevent.min_delta_ns = slop;
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+	xen_vcpuop_clockevent.min_delta_ticks = slop;
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+
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+	return 0;
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+}
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+early_param("xen_timer_slop", parse_xen_timer_slop);