--- /dev/null
+From b46b4a8a57c377b72a98c7930a9f6969d2d4784e Mon Sep 17 00:00:00 2001
+From: Vineeth Pillai <viremana@linux.microsoft.com>
+Date: Fri, 21 Aug 2020 15:28:49 +0000
+Subject: hv_utils: drain the timesync packets on onchannelcallback
+
+From: Vineeth Pillai <viremana@linux.microsoft.com>
+
+commit b46b4a8a57c377b72a98c7930a9f6969d2d4784e upstream.
+
+There could be instances where a system stall prevents the timesync
+packets to be consumed. And this might lead to more than one packet
+pending in the ring buffer. Current code empties one packet per callback
+and it might be a stale one. So drain all the packets from ring buffer
+on each callback.
+
+Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com>
+Reviewed-by: Michael Kelley <mikelley@microsoft.com>
+Link: https://lore.kernel.org/r/20200821152849.99517-1-viremana@linux.microsoft.com
+Signed-off-by: Wei Liu <wei.liu@kernel.org>
+[ The old code in the upstream commit uses HV_HYP_PAGE_SIZE, but
+ the old code in 5.4.y sitll uses PAGE_SIZE. Fixed this manually for 5.4.y.
+ Note: 5.4.y already has the define HV_HYP_PAGE_SIZE, so the new code in
+ in the upstream commit works for 5.4.y.
+ If there are multiple messages in the host-to-guest ringbuffer of the TimeSync
+ device, 5.4.y only handles 1 message, and later the host puts new messages
+ into the ringbuffer without signaling the guest because the ringbuffer is not
+ empty, causing a "hung" ringbuffer. Backported the mainline fix for this issue.]
+Signed-off-by: Dexuan Cui <decui@microsoft.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/hv/hv_util.c | 19 ++++++++++++++++---
+ 1 file changed, 16 insertions(+), 3 deletions(-)
+
+--- a/drivers/hv/hv_util.c
++++ b/drivers/hv/hv_util.c
+@@ -283,10 +283,23 @@ static void timesync_onchannelcallback(v
+ struct ictimesync_ref_data *refdata;
+ u8 *time_txf_buf = util_timesynch.recv_buffer;
+
+- vmbus_recvpacket(channel, time_txf_buf,
+- PAGE_SIZE, &recvlen, &requestid);
++ /*
++ * Drain the ring buffer and use the last packet to update
++ * host_ts
++ */
++ while (1) {
++ int ret = vmbus_recvpacket(channel, time_txf_buf,
++ HV_HYP_PAGE_SIZE, &recvlen,
++ &requestid);
++ if (ret) {
++ pr_warn_once("TimeSync IC pkt recv failed (Err: %d)\n",
++ ret);
++ break;
++ }
++
++ if (!recvlen)
++ break;
+
+- if (recvlen > 0) {
+ icmsghdrp = (struct icmsg_hdr *)&time_txf_buf[
+ sizeof(struct vmbuspipe_hdr)];
+
--- /dev/null
+From 07c54cc5988f19c9642fd463c2dbdac7fc52f777 Mon Sep 17 00:00:00 2001
+From: Oleg Nesterov <oleg@redhat.com>
+Date: Tue, 28 May 2024 14:20:19 +0200
+Subject: tick/nohz_full: Don't abuse smp_call_function_single() in tick_setup_device()
+
+From: Oleg Nesterov <oleg@redhat.com>
+
+commit 07c54cc5988f19c9642fd463c2dbdac7fc52f777 upstream.
+
+After the recent commit 5097cbcb38e6 ("sched/isolation: Prevent boot crash
+when the boot CPU is nohz_full") the kernel no longer crashes, but there is
+another problem.
+
+In this case tick_setup_device() calls tick_take_do_timer_from_boot() to
+update tick_do_timer_cpu and this triggers the WARN_ON_ONCE(irqs_disabled)
+in smp_call_function_single().
+
+Kill tick_take_do_timer_from_boot() and just use WRITE_ONCE(), the new
+comment explains why this is safe (thanks Thomas!).
+
+Fixes: 08ae95f4fd3b ("nohz_full: Allow the boot CPU to be nohz_full")
+Signed-off-by: Oleg Nesterov <oleg@redhat.com>
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+Cc: stable@vger.kernel.org
+Link: https://lore.kernel.org/r/20240528122019.GA28794@redhat.com
+Link: https://lore.kernel.org/all/20240522151742.GA10400@redhat.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/time/tick-common.c | 42 ++++++++++++++----------------------------
+ 1 file changed, 14 insertions(+), 28 deletions(-)
+
+--- a/kernel/time/tick-common.c
++++ b/kernel/time/tick-common.c
+@@ -177,26 +177,6 @@ void tick_setup_periodic(struct clock_ev
+ }
+ }
+
+-#ifdef CONFIG_NO_HZ_FULL
+-static void giveup_do_timer(void *info)
+-{
+- int cpu = *(unsigned int *)info;
+-
+- WARN_ON(tick_do_timer_cpu != smp_processor_id());
+-
+- tick_do_timer_cpu = cpu;
+-}
+-
+-static void tick_take_do_timer_from_boot(void)
+-{
+- int cpu = smp_processor_id();
+- int from = tick_do_timer_boot_cpu;
+-
+- if (from >= 0 && from != cpu)
+- smp_call_function_single(from, giveup_do_timer, &cpu, 1);
+-}
+-#endif
+-
+ /*
+ * Setup the tick device
+ */
+@@ -220,19 +200,25 @@ static void tick_setup_device(struct tic
+ tick_next_period = ktime_get();
+ #ifdef CONFIG_NO_HZ_FULL
+ /*
+- * The boot CPU may be nohz_full, in which case set
+- * tick_do_timer_boot_cpu so the first housekeeping
+- * secondary that comes up will take do_timer from
+- * us.
++ * The boot CPU may be nohz_full, in which case the
++ * first housekeeping secondary will take do_timer()
++ * from it.
+ */
+ if (tick_nohz_full_cpu(cpu))
+ tick_do_timer_boot_cpu = cpu;
+
+- } else if (tick_do_timer_boot_cpu != -1 &&
+- !tick_nohz_full_cpu(cpu)) {
+- tick_take_do_timer_from_boot();
++ } else if (tick_do_timer_boot_cpu != -1 && !tick_nohz_full_cpu(cpu)) {
+ tick_do_timer_boot_cpu = -1;
+- WARN_ON(tick_do_timer_cpu != cpu);
++ /*
++ * The boot CPU will stay in periodic (NOHZ disabled)
++ * mode until clocksource_done_booting() called after
++ * smp_init() selects a high resolution clocksource and
++ * timekeeping_notify() kicks the NOHZ stuff alive.
++ *
++ * So this WRITE_ONCE can only race with the READ_ONCE
++ * check in tick_periodic() but this race is harmless.
++ */
++ WRITE_ONCE(tick_do_timer_cpu, cpu);
+ #endif
+ }
+
projects / thirdparty / kernel / stable-queue.git / commitdiff
