From: Nicolas Saenz Julienne <hidden> Date: 2021-10-18 14:47:42
With 6caa5812e2d1 ("KVM: arm64: Use generic KVM xfer to guest work
function") all arm64 exit paths are properly equipped to handle the
POSIX timers' task work.
Deferring timer callbacks to thread context, not only limits the amount
of time spent in hard interrupt context, but is a safer
implementation[1], and will allow PREEMPT_RT setups to use KVM[2].
So let's enable POSIX_CPU_TIMERS_TASK_WORK on arm64.
[1] https://lore.kernel.org/all/20200716201923.228696399@linutronix.de/
[2] https://www.spinics.net/lists/linux-rt-users/msg24860.html
Signed-off-by: Nicolas Saenz Julienne <redacted>
---
This was tested by running all relevant kernel timer self-tests and
making sure KVM still works as expected.
arch/arm64/Kconfig | 1 +
1 file changed, 1 insertion(+)
From: Mark Rutland <mark.rutland@arm.com> Date: 2021-10-27 11:27:13
[adding Marc Z to Cc, since this affects KVM]
On Mon, Oct 18, 2021 at 04:47:13PM +0200, Nicolas Saenz Julienne wrote:
With 6caa5812e2d1 ("KVM: arm64: Use generic KVM xfer to guest work
function") all arm64 exit paths are properly equipped to handle the
POSIX timers' task work.
Deferring timer callbacks to thread context, not only limits the amount
of time spent in hard interrupt context, but is a safer
implementation[1], and will allow PREEMPT_RT setups to use KVM[2].
So let's enable POSIX_CPU_TIMERS_TASK_WORK on arm64.
[1] https://lore.kernel.org/all/20200716201923.228696399@linutronix.de/
[2] https://www.spinics.net/lists/linux-rt-users/msg24860.html
Regardless, this makes sense to me, and given you've tested it:
Acked-by: Mark Rutland <mark.rutland@arm.com>
Thanks,
Mark.
quoted hunk
---
This was tested by running all relevant kernel timer self-tests and
making sure KVM still works as expected.
arch/arm64/Kconfig | 1 +
1 file changed, 1 insertion(+)
From: Marc Zyngier <maz@kernel.org> Date: 2021-10-27 12:20:34
On Wed, 27 Oct 2021 12:26:58 +0100,
Mark Rutland [off-list ref] wrote:
[adding Marc Z to Cc, since this affects KVM]
On Mon, Oct 18, 2021 at 04:47:13PM +0200, Nicolas Saenz Julienne wrote:
quoted
With 6caa5812e2d1 ("KVM: arm64: Use generic KVM xfer to guest work
function") all arm64 exit paths are properly equipped to handle the
POSIX timers' task work.
Deferring timer callbacks to thread context, not only limits the amount
of time spent in hard interrupt context, but is a safer
implementation[1], and will allow PREEMPT_RT setups to use KVM[2].
So let's enable POSIX_CPU_TIMERS_TASK_WORK on arm64.
[1] https://lore.kernel.org/all/20200716201923.228696399@linutronix.de/
[2] https://www.spinics.net/lists/linux-rt-users/msg24860.html
Regardless, this makes sense to me, and given you've tested it:
Acked-by: Mark Rutland <mark.rutland@arm.com>
Thanks,
Mark.
quoted
---
This was tested by running all relevant kernel timer self-tests and
making sure KVM still works as expected.
arch/arm64/Kconfig | 1 +
1 file changed, 1 insertion(+)
Looks reasonable to me.
Acked-by: Marc Zyngier <maz@kernel.org>
M.
--
Without deviation from the norm, progress is not possible.
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From: Will Deacon <will@kernel.org> Date: 2021-10-28 09:20:56
On Mon, 18 Oct 2021 16:47:13 +0200, Nicolas Saenz Julienne wrote:
With 6caa5812e2d1 ("KVM: arm64: Use generic KVM xfer to guest work
function") all arm64 exit paths are properly equipped to handle the
POSIX timers' task work.
Deferring timer callbacks to thread context, not only limits the amount
of time spent in hard interrupt context, but is a safer
implementation[1], and will allow PREEMPT_RT setups to use KVM[2].
[...]