<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/clocksource, branch linux-5.10.y</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>clocksource/drivers/timer-integrator-ap: Add missing Kconfig dependency on OF</title>
<updated>2026-03-04T12:19:55+00:00</updated>
<author>
<name>Bartosz Golaszewski</name>
<email>bartosz.golaszewski@oss.qualcomm.com</email>
</author>
<published>2026-01-16T11:17:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=5fb5f733c611cd57c4c5b66015ee645a58e847f9'/>
<id>5fb5f733c611cd57c4c5b66015ee645a58e847f9</id>
<content type='text'>
[ Upstream commit 2246464821e2820572e6feefca2029f17629cc50 ]

This driver accesses the of_aliases global variable declared in
linux/of.h and defined in drivers/base/of.c. It requires OF support or
will cause a link failure. Add the missing Kconfig dependency.

Closes: https://lore.kernel.org/oe-kbuild-all/202601152233.og6LdeUo-lkp@intel.com/
Signed-off-by: Bartosz Golaszewski &lt;bartosz.golaszewski@oss.qualcomm.com&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Link: https://patch.msgid.link/20260116111723.10585-1-bartosz.golaszewski@oss.qualcomm.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 2246464821e2820572e6feefca2029f17629cc50 ]

This driver accesses the of_aliases global variable declared in
linux/of.h and defined in drivers/base/of.c. It requires OF support or
will cause a link failure. Add the missing Kconfig dependency.

Closes: https://lore.kernel.org/oe-kbuild-all/202601152233.og6LdeUo-lkp@intel.com/
Signed-off-by: Bartosz Golaszewski &lt;bartosz.golaszewski@oss.qualcomm.com&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Link: https://patch.msgid.link/20260116111723.10585-1-bartosz.golaszewski@oss.qualcomm.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/drivers/sh_tmu: Always leave device running after probe</title>
<updated>2026-03-04T12:19:55+00:00</updated>
<author>
<name>Niklas Söderlund</name>
<email>niklas.soderlund+renesas@ragnatech.se</email>
</author>
<published>2025-12-02T22:13:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=79d650695773f03de36b99228a090d33d1c18264'/>
<id>79d650695773f03de36b99228a090d33d1c18264</id>
<content type='text'>
[ Upstream commit b1278972b08e480990e2789bdc6a7c918bc349be ]

The TMU device can be used as both a clocksource and a clockevent
provider. The driver tries to be smart and power itself on and off, as
well as enabling and disabling its clock when it's not in operation.
This behavior is slightly altered if the TMU is used as an early
platform device in which case the device is left powered on after probe,
but the clock is still enabled and disabled at runtime.

This has worked for a long time, but recent improvements in PREEMPT_RT
and PROVE_LOCKING have highlighted an issue. As the TMU registers itself
as a clockevent provider, clockevents_register_device(), it needs to use
raw spinlocks internally as this is the context of which the clockevent
framework interacts with the TMU driver. However in the context of
holding a raw spinlock the TMU driver can't really manage its power
state or clock with calls to pm_runtime_*() and clk_*() as these calls
end up in other platform drivers using regular spinlocks to control
power and clocks.

This mix of spinlock contexts trips a lockdep warning.

    =============================
    [ BUG: Invalid wait context ]
    6.18.0-arm64-renesas-09926-gee959e7c5e34 #1 Not tainted
    -----------------------------
    swapper/0/0 is trying to lock:
    ffff000008c9e180 (&amp;dev-&gt;power.lock){-...}-{3:3}, at: __pm_runtime_resume+0x38/0x88
    other info that might help us debug this:
    context-{5:5}
    1 lock held by swapper/0/0:
    ccree e6601000.crypto: ARM CryptoCell 630P Driver: HW version 0xAF400001/0xDCC63000, Driver version 5.0
     #0: ffff8000817ec298
    ccree e6601000.crypto: ARM ccree device initialized
     (tick_broadcast_lock){-...}-{2:2}, at: __tick_broadcast_oneshot_control+0xa4/0x3a8
    stack backtrace:
    CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.18.0-arm64-renesas-09926-gee959e7c5e34 #1 PREEMPT
    Hardware name: Renesas Salvator-X 2nd version board based on r8a77965 (DT)
    Call trace:
     show_stack+0x14/0x1c (C)
     dump_stack_lvl+0x6c/0x90
     dump_stack+0x14/0x1c
     __lock_acquire+0x904/0x1584
     lock_acquire+0x220/0x34c
     _raw_spin_lock_irqsave+0x58/0x80
     __pm_runtime_resume+0x38/0x88
     sh_tmu_clock_event_set_oneshot+0x84/0xd4
     clockevents_switch_state+0xfc/0x13c
     tick_broadcast_set_event+0x30/0xa4
     __tick_broadcast_oneshot_control+0x1e0/0x3a8
     tick_broadcast_oneshot_control+0x30/0x40
     cpuidle_enter_state+0x40c/0x680
     cpuidle_enter+0x30/0x40
     do_idle+0x1f4/0x280
     cpu_startup_entry+0x34/0x40
     kernel_init+0x0/0x130
     do_one_initcall+0x0/0x230
     __primary_switched+0x88/0x90

For non-PREEMPT_RT builds this is not really an issue, but for
PREEMPT_RT builds where normal spinlocks can sleep this might be an
issue. Be cautious and always leave the power and clock running after
probe.

Signed-off-by: Niklas Söderlund &lt;niklas.soderlund+renesas@ragnatech.se&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Tested-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Link: https://patch.msgid.link/20251202221341.1856773-1-niklas.soderlund+renesas@ragnatech.se
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit b1278972b08e480990e2789bdc6a7c918bc349be ]

The TMU device can be used as both a clocksource and a clockevent
provider. The driver tries to be smart and power itself on and off, as
well as enabling and disabling its clock when it's not in operation.
This behavior is slightly altered if the TMU is used as an early
platform device in which case the device is left powered on after probe,
but the clock is still enabled and disabled at runtime.

This has worked for a long time, but recent improvements in PREEMPT_RT
and PROVE_LOCKING have highlighted an issue. As the TMU registers itself
as a clockevent provider, clockevents_register_device(), it needs to use
raw spinlocks internally as this is the context of which the clockevent
framework interacts with the TMU driver. However in the context of
holding a raw spinlock the TMU driver can't really manage its power
state or clock with calls to pm_runtime_*() and clk_*() as these calls
end up in other platform drivers using regular spinlocks to control
power and clocks.

This mix of spinlock contexts trips a lockdep warning.

    =============================
    [ BUG: Invalid wait context ]
    6.18.0-arm64-renesas-09926-gee959e7c5e34 #1 Not tainted
    -----------------------------
    swapper/0/0 is trying to lock:
    ffff000008c9e180 (&amp;dev-&gt;power.lock){-...}-{3:3}, at: __pm_runtime_resume+0x38/0x88
    other info that might help us debug this:
    context-{5:5}
    1 lock held by swapper/0/0:
    ccree e6601000.crypto: ARM CryptoCell 630P Driver: HW version 0xAF400001/0xDCC63000, Driver version 5.0
     #0: ffff8000817ec298
    ccree e6601000.crypto: ARM ccree device initialized
     (tick_broadcast_lock){-...}-{2:2}, at: __tick_broadcast_oneshot_control+0xa4/0x3a8
    stack backtrace:
    CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.18.0-arm64-renesas-09926-gee959e7c5e34 #1 PREEMPT
    Hardware name: Renesas Salvator-X 2nd version board based on r8a77965 (DT)
    Call trace:
     show_stack+0x14/0x1c (C)
     dump_stack_lvl+0x6c/0x90
     dump_stack+0x14/0x1c
     __lock_acquire+0x904/0x1584
     lock_acquire+0x220/0x34c
     _raw_spin_lock_irqsave+0x58/0x80
     __pm_runtime_resume+0x38/0x88
     sh_tmu_clock_event_set_oneshot+0x84/0xd4
     clockevents_switch_state+0xfc/0x13c
     tick_broadcast_set_event+0x30/0xa4
     __tick_broadcast_oneshot_control+0x1e0/0x3a8
     tick_broadcast_oneshot_control+0x30/0x40
     cpuidle_enter_state+0x40c/0x680
     cpuidle_enter+0x30/0x40
     do_idle+0x1f4/0x280
     cpu_startup_entry+0x34/0x40
     kernel_init+0x0/0x130
     do_one_initcall+0x0/0x230
     __primary_switched+0x88/0x90

For non-PREEMPT_RT builds this is not really an issue, but for
PREEMPT_RT builds where normal spinlocks can sleep this might be an
issue. Be cautious and always leave the power and clock running after
probe.

Signed-off-by: Niklas Söderlund &lt;niklas.soderlund+renesas@ragnatech.se&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Tested-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Link: https://patch.msgid.link/20251202221341.1856773-1-niklas.soderlund+renesas@ragnatech.se
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/drivers/vf-pit: Replace raw_readl/writel to readl/writel</title>
<updated>2025-12-06T21:08:09+00:00</updated>
<author>
<name>Daniel Lezcano</name>
<email>daniel.lezcano@linaro.org</email>
</author>
<published>2025-08-04T15:23:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9e8c3173a79c44cbd74be59410fcfa10da556ea4'/>
<id>9e8c3173a79c44cbd74be59410fcfa10da556ea4</id>
<content type='text'>
[ Upstream commit 0b781f527d6f99e68e5b3780ae03cd69a7cb5c0c ]

The driver uses the raw_readl() and raw_writel() functions. Those are
not for MMIO devices. Replace them with readl() and writel()

[ dlezcano: Fixed typo in the subject s/reald/readl/ ]

Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Acked-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Link: https://lore.kernel.org/r/20250804152344.1109310-2-daniel.lezcano@linaro.org
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 0b781f527d6f99e68e5b3780ae03cd69a7cb5c0c ]

The driver uses the raw_readl() and raw_writel() functions. Those are
not for MMIO devices. Replace them with readl() and writel()

[ dlezcano: Fixed typo in the subject s/reald/readl/ ]

Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Acked-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Link: https://lore.kernel.org/r/20250804152344.1109310-2-daniel.lezcano@linaro.org
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/drivers/clps711x: Fix resource leaks in error paths</title>
<updated>2025-10-29T13:01:08+00:00</updated>
<author>
<name>Zhen Ni</name>
<email>zhen.ni@easystack.cn</email>
</author>
<published>2025-08-14T12:33:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3bec2c6644d1f4c8f0ffc1f59c8bd1ccc79a2c13'/>
<id>3bec2c6644d1f4c8f0ffc1f59c8bd1ccc79a2c13</id>
<content type='text'>
commit cd32e596f02fc981674573402c1138f616df1728 upstream.

The current implementation of clps711x_timer_init() has multiple error
paths that directly return without releasing the base I/O memory mapped
via of_iomap(). Fix of_iomap leaks in error paths.

Fixes: 04410efbb6bc ("clocksource/drivers/clps711x: Convert init function to return error")
Fixes: 2a6a8e2d9004 ("clocksource/drivers/clps711x: Remove board support")
Signed-off-by: Zhen Ni &lt;zhen.ni@easystack.cn&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250814123324.1516495-1-zhen.ni@easystack.cn
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit cd32e596f02fc981674573402c1138f616df1728 upstream.

The current implementation of clps711x_timer_init() has multiple error
paths that directly return without releasing the base I/O memory mapped
via of_iomap(). Fix of_iomap leaks in error paths.

Fixes: 04410efbb6bc ("clocksource/drivers/clps711x: Convert init function to return error")
Fixes: 2a6a8e2d9004 ("clocksource/drivers/clps711x: Remove board support")
Signed-off-by: Zhen Ni &lt;zhen.ni@easystack.cn&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250814123324.1516495-1-zhen.ni@easystack.cn
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource: mips-gic-timer: Enable counter when CPUs start</title>
<updated>2025-06-04T12:37:03+00:00</updated>
<author>
<name>Paul Burton</name>
<email>paulburton@kernel.org</email>
</author>
<published>2025-01-29T12:32:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=4cb82b499831876f9bb003107d986c5d53eeee1c'/>
<id>4cb82b499831876f9bb003107d986c5d53eeee1c</id>
<content type='text'>
[ Upstream commit 3128b0a2e0cf6e07aa78e5f8cf7dd9cd59dc8174 ]

In multi-cluster MIPS I6500 systems there is a GIC in each cluster,
each with its own counter. When a cluster powers up the counter will
be stopped, with the COUNTSTOP bit set in the GIC_CONFIG register.

In single cluster systems, it has been fine to clear COUNTSTOP once
in gic_clocksource_of_init() to start the counter. In multi-cluster
systems, this will only have started the counter in the boot cluster,
and any CPUs in other clusters will find their counter stopped which
will break the GIC clock_event_device.

Resolve this by having CPUs clear the COUNTSTOP bit when they come
online, using the existing gic_starting_cpu() CPU hotplug callback. This
will allow CPUs in secondary clusters to ensure that the cluster's GIC
counter is running as expected.

Signed-off-by: Paul Burton &lt;paulburton@kernel.org&gt;
Signed-off-by: Chao-ying Fu &lt;cfu@wavecomp.com&gt;
Signed-off-by: Dragan Mladjenovic &lt;dragan.mladjenovic@syrmia.com&gt;
Signed-off-by: Aleksandar Rikalo &lt;arikalo@gmail.com&gt;
Reviewed-by: Philippe Mathieu-Daudé &lt;philmd@linaro.org&gt;
Tested-by: Serge Semin &lt;fancer.lancer@gmail.com&gt;
Tested-by: Gregory CLEMENT &lt;gregory.clement@bootlin.com&gt;
Acked-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 3128b0a2e0cf6e07aa78e5f8cf7dd9cd59dc8174 ]

In multi-cluster MIPS I6500 systems there is a GIC in each cluster,
each with its own counter. When a cluster powers up the counter will
be stopped, with the COUNTSTOP bit set in the GIC_CONFIG register.

In single cluster systems, it has been fine to clear COUNTSTOP once
in gic_clocksource_of_init() to start the counter. In multi-cluster
systems, this will only have started the counter in the boot cluster,
and any CPUs in other clusters will find their counter stopped which
will break the GIC clock_event_device.

Resolve this by having CPUs clear the COUNTSTOP bit when they come
online, using the existing gic_starting_cpu() CPU hotplug callback. This
will allow CPUs in secondary clusters to ensure that the cluster's GIC
counter is running as expected.

Signed-off-by: Paul Burton &lt;paulburton@kernel.org&gt;
Signed-off-by: Chao-ying Fu &lt;cfu@wavecomp.com&gt;
Signed-off-by: Dragan Mladjenovic &lt;dragan.mladjenovic@syrmia.com&gt;
Signed-off-by: Aleksandar Rikalo &lt;arikalo@gmail.com&gt;
Reviewed-by: Philippe Mathieu-Daudé &lt;philmd@linaro.org&gt;
Tested-by: Serge Semin &lt;fancer.lancer@gmail.com&gt;
Tested-by: Gregory CLEMENT &lt;gregory.clement@bootlin.com&gt;
Acked-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/i8253: Use raw_spinlock_irqsave() in clockevent_i8253_disable()</title>
<updated>2025-06-04T12:36:57+00:00</updated>
<author>
<name>Sebastian Andrzej Siewior</name>
<email>bigeasy@linutronix.de</email>
</author>
<published>2025-04-04T13:31:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6f37f3325a533b34bb019dd4fb233b1cce3a5317'/>
<id>6f37f3325a533b34bb019dd4fb233b1cce3a5317</id>
<content type='text'>
commit 94cff94634e506a4a44684bee1875d2dbf782722 upstream.

On x86 during boot, clockevent_i8253_disable() can be invoked via
x86_late_time_init -&gt; hpet_time_init() -&gt; pit_timer_init() which happens
with enabled interrupts.

If some of the old i8253 hardware is actually used then lockdep will notice
that i8253_lock is used in hard interrupt context. This causes lockdep to
complain because it observed the lock being acquired with interrupts
enabled and in hard interrupt context.

Make clockevent_i8253_disable() acquire the lock with
raw_spinlock_irqsave() to cure this.

[ tglx: Massage change log and use guard() ]

Fixes: c8c4076723dac ("x86/timer: Skip PIT initialization on modern chipsets")
Signed-off-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250404133116.p-XRWJXf@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 94cff94634e506a4a44684bee1875d2dbf782722 upstream.

On x86 during boot, clockevent_i8253_disable() can be invoked via
x86_late_time_init -&gt; hpet_time_init() -&gt; pit_timer_init() which happens
with enabled interrupts.

If some of the old i8253 hardware is actually used then lockdep will notice
that i8253_lock is used in hard interrupt context. This causes lockdep to
complain because it observed the lock being acquired with interrupts
enabled and in hard interrupt context.

Make clockevent_i8253_disable() acquire the lock with
raw_spinlock_irqsave() to cure this.

[ tglx: Massage change log and use guard() ]

Fixes: c8c4076723dac ("x86/timer: Skip PIT initialization on modern chipsets")
Signed-off-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250404133116.p-XRWJXf@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/drivers/stm32-lptimer: Use wakeup capable instead of init wakeup</title>
<updated>2025-05-02T05:40:54+00:00</updated>
<author>
<name>Alexandre Torgue</name>
<email>alexandre.torgue@foss.st.com</email>
</author>
<published>2025-03-06T10:25:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c5fbabbcfcb365079b9510621f9aa7e0d1de72d7'/>
<id>c5fbabbcfcb365079b9510621f9aa7e0d1de72d7</id>
<content type='text'>
commit 96bf4b89a6ab22426ad83ef76e66c72a5a8daca0 upstream.

"wakeup-source" property describes a device which has wakeup capability
but should not force this device as a wakeup source.

Fixes: 48b41c5e2de6 ("clocksource: Add Low Power STM32 timers driver")
Cc: stable@vger.kernel.org
Signed-off-by: Alexandre Torgue &lt;alexandre.torgue@foss.st.com&gt;
Signed-off-by: Fabrice Gasnier &lt;fabrice.gasnier@foss.st.com&gt;
Rule: add
Link: https://lore.kernel.org/stable/20250306083407.2374894-1-fabrice.gasnier%40foss.st.com
Link: https://lore.kernel.org/r/20250306102501.2980153-1-fabrice.gasnier@foss.st.com
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 96bf4b89a6ab22426ad83ef76e66c72a5a8daca0 upstream.

"wakeup-source" property describes a device which has wakeup capability
but should not force this device as a wakeup source.

Fixes: 48b41c5e2de6 ("clocksource: Add Low Power STM32 timers driver")
Cc: stable@vger.kernel.org
Signed-off-by: Alexandre Torgue &lt;alexandre.torgue@foss.st.com&gt;
Signed-off-by: Fabrice Gasnier &lt;fabrice.gasnier@foss.st.com&gt;
Rule: add
Link: https://lore.kernel.org/stable/20250306083407.2374894-1-fabrice.gasnier%40foss.st.com
Link: https://lore.kernel.org/r/20250306102501.2980153-1-fabrice.gasnier@foss.st.com
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clockevents/drivers/i8253: Fix stop sequence for timer 0</title>
<updated>2025-04-10T12:30:48+00:00</updated>
<author>
<name>David Woodhouse</name>
<email>dwmw@amazon.co.uk</email>
</author>
<published>2024-08-02T13:55:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9c096d9aefcf8c6df856d1764849cd1840933a06'/>
<id>9c096d9aefcf8c6df856d1764849cd1840933a06</id>
<content type='text'>
commit 531b2ca0a940ac9db03f246c8b77c4201de72b00 upstream.

According to the data sheet, writing the MODE register should stop the
counter (and thus the interrupts). This appears to work on real hardware,
at least modern Intel and AMD systems. It should also work on Hyper-V.

However, on some buggy virtual machines the mode change doesn't have any
effect until the counter is subsequently loaded (or perhaps when the IRQ
next fires).

So, set MODE 0 and then load the counter, to ensure that those buggy VMs
do the right thing and the interrupts stop. And then write MODE 0 *again*
to stop the counter on compliant implementations too.

Apparently, Hyper-V keeps firing the IRQ *repeatedly* even in mode zero
when it should only happen once, but the second MODE write stops that too.

Userspace test program (mostly written by tglx):
=====
 #include &lt;stdio.h&gt;
 #include &lt;unistd.h&gt;
 #include &lt;stdlib.h&gt;
 #include &lt;stdint.h&gt;
 #include &lt;sys/io.h&gt;

static __always_inline void __out##bwl(type value, uint16_t port)	\
{									\
	asm volatile("out" #bwl " %" #bw "0, %w1"			\
		     : : "a"(value), "Nd"(port));			\
}									\
									\
static __always_inline type __in##bwl(uint16_t port)			\
{									\
	type value;							\
	asm volatile("in" #bwl " %w1, %" #bw "0"			\
		     : "=a"(value) : "Nd"(port));			\
	return value;							\
}

BUILDIO(b, b, uint8_t)

 #define inb __inb
 #define outb __outb

 #define PIT_MODE	0x43
 #define PIT_CH0	0x40
 #define PIT_CH2	0x42

static int is8254;

static void dump_pit(void)
{
	if (is8254) {
		// Latch and output counter and status
		outb(0xC2, PIT_MODE);
		printf("%02x %02x %02x\n", inb(PIT_CH0), inb(PIT_CH0), inb(PIT_CH0));
	} else {
		// Latch and output counter
		outb(0x0, PIT_MODE);
		printf("%02x %02x\n", inb(PIT_CH0), inb(PIT_CH0));
	}
}

int main(int argc, char* argv[])
{
	int nr_counts = 2;

	if (argc &gt; 1)
		nr_counts = atoi(argv[1]);

	if (argc &gt; 2)
		is8254 = 1;

	if (ioperm(0x40, 4, 1) != 0)
		return 1;

	dump_pit();

	printf("Set oneshot\n");
	outb(0x38, PIT_MODE);
	outb(0x00, PIT_CH0);
	outb(0x0F, PIT_CH0);

	dump_pit();
	usleep(1000);
	dump_pit();

	printf("Set periodic\n");
	outb(0x34, PIT_MODE);
	outb(0x00, PIT_CH0);
	outb(0x0F, PIT_CH0);

	dump_pit();
	usleep(1000);
	dump_pit();
	dump_pit();
	usleep(100000);
	dump_pit();
	usleep(100000);
	dump_pit();

	printf("Set stop (%d counter writes)\n", nr_counts);
	outb(0x30, PIT_MODE);
	while (nr_counts--)
		outb(0xFF, PIT_CH0);

	dump_pit();
	usleep(100000);
	dump_pit();
	usleep(100000);
	dump_pit();

	printf("Set MODE 0\n");
	outb(0x30, PIT_MODE);

	dump_pit();
	usleep(100000);
	dump_pit();
	usleep(100000);
	dump_pit();

	return 0;
}
=====

Suggested-by: Sean Christopherson &lt;seanjc@google.com&gt;
Co-developed-by: Li RongQing &lt;lirongqing@baidu.com&gt;
Signed-off-by: Li RongQing &lt;lirongqing@baidu.com&gt;
Signed-off-by: David Woodhouse &lt;dwmw@amazon.co.uk&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Tested-by: Michael Kelley &lt;mhkelley@outlook.com&gt;
Link: https://lore.kernel.org/all/20240802135555.564941-2-dwmw2@infradead.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 531b2ca0a940ac9db03f246c8b77c4201de72b00 upstream.

According to the data sheet, writing the MODE register should stop the
counter (and thus the interrupts). This appears to work on real hardware,
at least modern Intel and AMD systems. It should also work on Hyper-V.

However, on some buggy virtual machines the mode change doesn't have any
effect until the counter is subsequently loaded (or perhaps when the IRQ
next fires).

So, set MODE 0 and then load the counter, to ensure that those buggy VMs
do the right thing and the interrupts stop. And then write MODE 0 *again*
to stop the counter on compliant implementations too.

Apparently, Hyper-V keeps firing the IRQ *repeatedly* even in mode zero
when it should only happen once, but the second MODE write stops that too.

Userspace test program (mostly written by tglx):
=====
 #include &lt;stdio.h&gt;
 #include &lt;unistd.h&gt;
 #include &lt;stdlib.h&gt;
 #include &lt;stdint.h&gt;
 #include &lt;sys/io.h&gt;

static __always_inline void __out##bwl(type value, uint16_t port)	\
{									\
	asm volatile("out" #bwl " %" #bw "0, %w1"			\
		     : : "a"(value), "Nd"(port));			\
}									\
									\
static __always_inline type __in##bwl(uint16_t port)			\
{									\
	type value;							\
	asm volatile("in" #bwl " %w1, %" #bw "0"			\
		     : "=a"(value) : "Nd"(port));			\
	return value;							\
}

BUILDIO(b, b, uint8_t)

 #define inb __inb
 #define outb __outb

 #define PIT_MODE	0x43
 #define PIT_CH0	0x40
 #define PIT_CH2	0x42

static int is8254;

static void dump_pit(void)
{
	if (is8254) {
		// Latch and output counter and status
		outb(0xC2, PIT_MODE);
		printf("%02x %02x %02x\n", inb(PIT_CH0), inb(PIT_CH0), inb(PIT_CH0));
	} else {
		// Latch and output counter
		outb(0x0, PIT_MODE);
		printf("%02x %02x\n", inb(PIT_CH0), inb(PIT_CH0));
	}
}

int main(int argc, char* argv[])
{
	int nr_counts = 2;

	if (argc &gt; 1)
		nr_counts = atoi(argv[1]);

	if (argc &gt; 2)
		is8254 = 1;

	if (ioperm(0x40, 4, 1) != 0)
		return 1;

	dump_pit();

	printf("Set oneshot\n");
	outb(0x38, PIT_MODE);
	outb(0x00, PIT_CH0);
	outb(0x0F, PIT_CH0);

	dump_pit();
	usleep(1000);
	dump_pit();

	printf("Set periodic\n");
	outb(0x34, PIT_MODE);
	outb(0x00, PIT_CH0);
	outb(0x0F, PIT_CH0);

	dump_pit();
	usleep(1000);
	dump_pit();
	dump_pit();
	usleep(100000);
	dump_pit();
	usleep(100000);
	dump_pit();

	printf("Set stop (%d counter writes)\n", nr_counts);
	outb(0x30, PIT_MODE);
	while (nr_counts--)
		outb(0xFF, PIT_CH0);

	dump_pit();
	usleep(100000);
	dump_pit();
	usleep(100000);
	dump_pit();

	printf("Set MODE 0\n");
	outb(0x30, PIT_MODE);

	dump_pit();
	usleep(100000);
	dump_pit();
	usleep(100000);
	dump_pit();

	return 0;
}
=====

Suggested-by: Sean Christopherson &lt;seanjc@google.com&gt;
Co-developed-by: Li RongQing &lt;lirongqing@baidu.com&gt;
Signed-off-by: Li RongQing &lt;lirongqing@baidu.com&gt;
Signed-off-by: David Woodhouse &lt;dwmw@amazon.co.uk&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Tested-by: Michael Kelley &lt;mhkelley@outlook.com&gt;
Link: https://lore.kernel.org/all/20240802135555.564941-2-dwmw2@infradead.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/i8253: Disable PIT timer 0 when not in use</title>
<updated>2025-03-13T11:47:24+00:00</updated>
<author>
<name>David Woodhouse</name>
<email>dwmw@amazon.co.uk</email>
</author>
<published>2024-08-02T13:55:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=eab8746deb43ddd592276781a023cb2ee58e2ede'/>
<id>eab8746deb43ddd592276781a023cb2ee58e2ede</id>
<content type='text'>
commit 70e6b7d9ae3c63df90a7bba7700e8d5c300c3c60 upstream.

Leaving the PIT interrupt running can cause noticeable steal time for
virtual guests. The VMM generally has a timer which toggles the IRQ input
to the PIC and I/O APIC, which takes CPU time away from the guest. Even
on real hardware, running the counter may use power needlessly (albeit
not much).

Make sure it's turned off if it isn't going to be used.

Signed-off-by: David Woodhouse &lt;dwmw@amazon.co.uk&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Tested-by: Michael Kelley &lt;mhkelley@outlook.com&gt;
Link: https://lore.kernel.org/all/20240802135555.564941-1-dwmw2@infradead.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 70e6b7d9ae3c63df90a7bba7700e8d5c300c3c60 upstream.

Leaving the PIT interrupt running can cause noticeable steal time for
virtual guests. The VMM generally has a timer which toggles the IRQ input
to the PIC and I/O APIC, which takes CPU time away from the guest. Even
on real hardware, running the counter may use power needlessly (albeit
not much).

Make sure it's turned off if it isn't going to be used.

Signed-off-by: David Woodhouse &lt;dwmw@amazon.co.uk&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Tested-by: Michael Kelley &lt;mhkelley@outlook.com&gt;
Link: https://lore.kernel.org/all/20240802135555.564941-1-dwmw2@infradead.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/hyperv: Fix hv tsc page based sched_clock for hibernation</title>
<updated>2025-01-09T12:25:00+00:00</updated>
<author>
<name>Naman Jain</name>
<email>namjain@linux.microsoft.com</email>
</author>
<published>2024-09-17T05:39:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=36c569dfa72441eb9e8452d670cf3164d9938d3a'/>
<id>36c569dfa72441eb9e8452d670cf3164d9938d3a</id>
<content type='text'>
commit bcc80dec91ee745b3d66f3e48f0ec2efdea97149 upstream.

read_hv_sched_clock_tsc() assumes that the Hyper-V clock counter is
bigger than the variable hv_sched_clock_offset, which is cached during
early boot, but depending on the timing this assumption may be false
when a hibernated VM starts again (the clock counter starts from 0
again) and is resuming back (Note: hv_init_tsc_clocksource() is not
called during hibernation/resume); consequently,
read_hv_sched_clock_tsc() may return a negative integer (which is
interpreted as a huge positive integer since the return type is u64)
and new kernel messages are prefixed with huge timestamps before
read_hv_sched_clock_tsc() grows big enough (which typically takes
several seconds).

Fix the issue by saving the Hyper-V clock counter just before the
suspend, and using it to correct the hv_sched_clock_offset in
resume. This makes hv tsc page based sched_clock continuous and ensures
that post resume, it starts from where it left off during suspend.
Override x86_platform.save_sched_clock_state and
x86_platform.restore_sched_clock_state routines to correct this as soon
as possible.

Note: if Invariant TSC is available, the issue doesn't happen because
1) we don't register read_hv_sched_clock_tsc() for sched clock:
See commit e5313f1c5404 ("clocksource/drivers/hyper-v: Rework
clocksource and sched clock setup");
2) the common x86 code adjusts TSC similarly: see
__restore_processor_state() -&gt;  tsc_verify_tsc_adjust(true) and
x86_platform.restore_sched_clock_state().

Cc: stable@vger.kernel.org
Fixes: 1349401ff1aa ("clocksource/drivers/hyper-v: Suspend/resume Hyper-V clocksource for hibernation")
Co-developed-by: Dexuan Cui &lt;decui@microsoft.com&gt;
Signed-off-by: Dexuan Cui &lt;decui@microsoft.com&gt;
Signed-off-by: Naman Jain &lt;namjain@linux.microsoft.com&gt;
Reviewed-by: Michael Kelley &lt;mhklinux@outlook.com&gt;
Link: https://lore.kernel.org/r/20240917053917.76787-1-namjain@linux.microsoft.com
Signed-off-by: Wei Liu &lt;wei.liu@kernel.org&gt;
Message-ID: &lt;20240917053917.76787-1-namjain@linux.microsoft.com&gt;
Signed-off-by: Naman Jain &lt;namjain@linux.microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit bcc80dec91ee745b3d66f3e48f0ec2efdea97149 upstream.

read_hv_sched_clock_tsc() assumes that the Hyper-V clock counter is
bigger than the variable hv_sched_clock_offset, which is cached during
early boot, but depending on the timing this assumption may be false
when a hibernated VM starts again (the clock counter starts from 0
again) and is resuming back (Note: hv_init_tsc_clocksource() is not
called during hibernation/resume); consequently,
read_hv_sched_clock_tsc() may return a negative integer (which is
interpreted as a huge positive integer since the return type is u64)
and new kernel messages are prefixed with huge timestamps before
read_hv_sched_clock_tsc() grows big enough (which typically takes
several seconds).

Fix the issue by saving the Hyper-V clock counter just before the
suspend, and using it to correct the hv_sched_clock_offset in
resume. This makes hv tsc page based sched_clock continuous and ensures
that post resume, it starts from where it left off during suspend.
Override x86_platform.save_sched_clock_state and
x86_platform.restore_sched_clock_state routines to correct this as soon
as possible.

Note: if Invariant TSC is available, the issue doesn't happen because
1) we don't register read_hv_sched_clock_tsc() for sched clock:
See commit e5313f1c5404 ("clocksource/drivers/hyper-v: Rework
clocksource and sched clock setup");
2) the common x86 code adjusts TSC similarly: see
__restore_processor_state() -&gt;  tsc_verify_tsc_adjust(true) and
x86_platform.restore_sched_clock_state().

Cc: stable@vger.kernel.org
Fixes: 1349401ff1aa ("clocksource/drivers/hyper-v: Suspend/resume Hyper-V clocksource for hibernation")
Co-developed-by: Dexuan Cui &lt;decui@microsoft.com&gt;
Signed-off-by: Dexuan Cui &lt;decui@microsoft.com&gt;
Signed-off-by: Naman Jain &lt;namjain@linux.microsoft.com&gt;
Reviewed-by: Michael Kelley &lt;mhklinux@outlook.com&gt;
Link: https://lore.kernel.org/r/20240917053917.76787-1-namjain@linux.microsoft.com
Signed-off-by: Wei Liu &lt;wei.liu@kernel.org&gt;
Message-ID: &lt;20240917053917.76787-1-namjain@linux.microsoft.com&gt;
Signed-off-by: Naman Jain &lt;namjain@linux.microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
