[PATCH RT 0/2] Linux 3.4.107-rt134-rc1

[PATCH RT 0/2] Linux 3.4.107-rt134-rc1

[Steven Rostedt]

Dear RT Folks,

This is the RT stable review cycle of patch 3.4.107-rt134-rc1.

Please scream at me if I messed something up. Please test the patches too.

The -rc release will be uploaded to kernel.org and will be deleted when
the final release is out. This is just a review release (or release candidate).

The pre-releases will not be pushed to the git repository, only the
final release is.

If all goes well, this patch will be converted to the next main release
on 5/18/2015.

Enjoy,

-- Steve


To build 3.4.107-rt134-rc1 directly, the following patches should be applied:

  http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.4.tar.xz

  http://www.kernel.org/pub/linux/kernel/v3.x/patch-3.4.107.xz

  http://www.kernel.org/pub/linux/kernel/projects/rt/3.4/patch-3.4.107-rt134-rc1.patch.xz

You can also build from 3.4.107-rt133 by applying the incremental patch:

http://www.kernel.org/pub/linux/kernel/projects/rt/3.4/incr/patch-3.4.107-rt133-rt134-rc1.patch.xz


Changes from 3.4.107-rt133:

---


Marcelo Tosatti (1):
      KVM: lapic: mark LAPIC timer handler as irqsafe

Steven Rostedt (Red Hat) (1):
      Linux 3.4.107-rt134-rc1

----
 arch/x86/kvm/lapic.c | 42 +++++++++++++++++++++++++++++++++++++++---
 localversion-rt      |  2 +-
 2 files changed, 40 insertions(+), 4 deletions(-)

[PATCH RT 1/2] KVM: lapic: mark LAPIC timer handler as irqsafe

[Steven Rostedt]

[-- Attachment #1: 0001-KVM-lapic-mark-LAPIC-timer-handler-as-irqsafe.patch --]
[-- Type: text/plain, Size: 3333 bytes --]

3.4.107-rt134-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Marcelo Tosatti <mtosatti@redhat.com>

Since lapic timer handler only wakes up a simple waitqueue,
it can be executed from hardirq context.

Also handle the case where hrtimer_start_expires fails due to -ETIME,
by injecting the interrupt to the guest immediately.

Reduces average cyclictest latency by 3us.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/x86/kvm/lapic.c | 42 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 578613da251e..b4bdc60f171f 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -683,8 +683,38 @@ static void update_divide_count(struct kvm_lapic *apic)
 				   apic->divide_count);
 }
 
+
+static enum hrtimer_restart apic_timer_fn(struct hrtimer *data);
+
+static void apic_timer_expired(struct hrtimer *data)
+{
+	int ret, i = 0;
+	enum hrtimer_restart r;
+	struct kvm_timer *ktimer = container_of(data, struct kvm_timer, timer);
+
+	r = apic_timer_fn(data);
+
+	if (r == HRTIMER_RESTART) {
+		do {
+			ret = hrtimer_start_expires(data, HRTIMER_MODE_ABS);
+			if (ret == -ETIME)
+				hrtimer_add_expires_ns(&ktimer->timer,
+							ktimer->period);
+			i++;
+		} while (ret == -ETIME && i < 10);
+
+		if (ret == -ETIME) {
+			printk_once(KERN_ERR "%s: failed to reprogram timer\n",
+			       __func__);
+			WARN_ON_ONCE(1);
+		}
+	}
+}
+
+
 static void start_apic_timer(struct kvm_lapic *apic)
 {
+	int ret;
 	ktime_t now;
 	atomic_set(&apic->lapic_timer.pending, 0);
 
@@ -714,9 +744,11 @@ static void start_apic_timer(struct kvm_lapic *apic)
 			}
 		}
 
-		hrtimer_start(&apic->lapic_timer.timer,
+		ret = hrtimer_start(&apic->lapic_timer.timer,
 			      ktime_add_ns(now, apic->lapic_timer.period),
 			      HRTIMER_MODE_ABS);
+		if (ret == -ETIME)
+			apic_timer_expired(&apic->lapic_timer.timer);
 
 		apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016"
 			   PRIx64 ", "
@@ -746,8 +778,10 @@ static void start_apic_timer(struct kvm_lapic *apic)
 			ns = (tscdeadline - guest_tsc) * 1000000ULL;
 			do_div(ns, this_tsc_khz);
 		}
-		hrtimer_start(&apic->lapic_timer.timer,
+		ret = hrtimer_start(&apic->lapic_timer.timer,
 			ktime_add_ns(now, ns), HRTIMER_MODE_ABS);
+		if (ret == -ETIME)
+			apic_timer_expired(&apic->lapic_timer.timer);
 
 		local_irq_restore(flags);
 	}
@@ -1177,6 +1211,7 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu)
 	hrtimer_init(&apic->lapic_timer.timer, CLOCK_MONOTONIC,
 		     HRTIMER_MODE_ABS);
 	apic->lapic_timer.timer.function = kvm_timer_fn;
+	apic->lapic_timer.timer.irqsafe = 1;
 	apic->lapic_timer.t_ops = &lapic_timer_ops;
 	apic->lapic_timer.kvm = vcpu->kvm;
 	apic->lapic_timer.vcpu = vcpu;
@@ -1273,7 +1308,8 @@ void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)
 
 	timer = &apic->lapic_timer.timer;
 	if (hrtimer_cancel(timer))
-		hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
+		if (hrtimer_start_expires(timer, HRTIMER_MODE_ABS) == -ETIME)
+			apic_timer_expired(timer);
 }
 
 void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu)
-- 
2.1.4

[PATCH RT 2/2] Linux 3.4.107-rt134-rc1

[Steven Rostedt]

[-- Attachment #1: 0002-Linux-3.4.107-rt134-rc1.patch --]
[-- Type: text/plain, Size: 417 bytes --]

3.4.107-rt134-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

---
 localversion-rt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/localversion-rt b/localversion-rt
index c2c7e0fb6685..74bebbe8d7ed 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt133
+-rt134-rc1
-- 
2.1.4