This is a note to let you know that I've just added the patch titled
xen/events: Handle VIRQ_TIMER before any other hardirq in event loop.
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xen-events-handle-virq_timer-before-any-other-hardirq-in-event-loop.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From bee980d9e9642e96351fa3ca9077b853ecf62f57 Mon Sep 17 00:00:00 2001
From: Keir Fraser <keir.fraser@xxxxxxxxxx>
Date: Thu, 28 Mar 2013 10:03:36 -0400
Subject: xen/events: Handle VIRQ_TIMER before any other hardirq in event loop.
From: Keir Fraser <keir.fraser@xxxxxxxxxx>
commit bee980d9e9642e96351fa3ca9077b853ecf62f57 upstream.
This avoids any other hardirq handler seeing a very stale jiffies
value immediately after wakeup from a long idle period. The one
observable symptom of this was a USB keyboard, with software keyboard
repeat, which would always repeat a key immediately that it was
pressed. This is due to the key press waking the guest, the key
handler immediately runs, sees an old jiffies value, and then that
jiffies value significantly updated, before the key is unpressed.
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/xen/events.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -1258,7 +1258,7 @@ static void __xen_evtchn_do_upcall(void)
{
int start_word_idx, start_bit_idx;
int word_idx, bit_idx;
- int i;
+ int i, irq;
int cpu = get_cpu();
struct shared_info *s = HYPERVISOR_shared_info;
struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
@@ -1266,6 +1266,8 @@ static void __xen_evtchn_do_upcall(void)
do {
unsigned long pending_words;
+ unsigned long pending_bits;
+ struct irq_desc *desc;
vcpu_info->evtchn_upcall_pending = 0;
@@ -1276,6 +1278,17 @@ static void __xen_evtchn_do_upcall(void)
/* Clear master flag /before/ clearing selector flag. */
wmb();
#endif
+ if ((irq = per_cpu(virq_to_irq, cpu)[VIRQ_TIMER]) != -1) {
+ int evtchn = evtchn_from_irq(irq);
+ word_idx = evtchn / BITS_PER_LONG;
+ pending_bits = evtchn % BITS_PER_LONG;
+ if (active_evtchns(cpu, s, word_idx) & (1ULL << pending_bits)) {
+ desc = irq_to_desc(irq);
+ if (desc)
+ generic_handle_irq_desc(irq, desc);
+ }
+ }
+
pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0);
start_word_idx = __this_cpu_read(current_word_idx);
@@ -1284,7 +1297,6 @@ static void __xen_evtchn_do_upcall(void)
word_idx = start_word_idx;
for (i = 0; pending_words != 0; i++) {
- unsigned long pending_bits;
unsigned long words;
words = MASK_LSBS(pending_words, word_idx);
@@ -1313,8 +1325,7 @@ static void __xen_evtchn_do_upcall(void)
do {
unsigned long bits;
- int port, irq;
- struct irq_desc *desc;
+ int port;
bits = MASK_LSBS(pending_bits, bit_idx);
Patches currently in stable-queue which might be from keir.fraser@xxxxxxxxxx are
queue-3.4/xen-events-handle-virq_timer-before-any-other-hardirq-in-event-loop.patch
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