Messages in this thread | | | Date | Wed, 27 Oct 2021 12:26:58 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH] arm64: Select POSIX_CPU_TIMERS_TASK_WORK |
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[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
Trivial nit: could we please make that second link:
https://lore.kernel.org/linux-rt-users/87v92bdnlx.ffs@tglx/
> Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Regardless, this makes sense to me, and given you've tested it:
Acked-by: Mark Rutland <mark.rutland@arm.com>
Thanks, Mark.
> > --- > > 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(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 789036cf74f5..ce0d0d254542 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -191,6 +191,7 @@ config ARM64 > select HAVE_PERF_REGS > select HAVE_PERF_USER_STACK_DUMP > select HAVE_REGS_AND_STACK_ACCESS_API > + select HAVE_POSIX_CPU_TIMERS_TASK_WORK > select HAVE_FUNCTION_ARG_ACCESS_API > select HAVE_FUTEX_CMPXCHG if FUTEX > select MMU_GATHER_RCU_TABLE_FREE > -- > 2.32.0 >
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