| Message ID | 20170805170241.22966-13-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Sun, 2017-08-06 at 03:02 +1000, Nicholas Piggin wrote: > The hardware can execute stop in any context, and KVM does not > require real mode. This saves a switch to real-mode when going > idle. +Paulus. > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- > arch/powerpc/kernel/idle_book3s.S | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S > index 75746111e2c4..8ac366a51bb5 100644 > --- a/arch/powerpc/kernel/idle_book3s.S > +++ b/arch/powerpc/kernel/idle_book3s.S > @@ -141,7 +141,16 @@ pnv_powersave_common: > std r5,_CCR(r1) > std r1,PACAR1(r13) > > +BEGIN_FTR_SECTION > + /* > + * POWER9 does not require real mode to stop, and does not set > + * hwthread_state for KVM (threads don't share MMU context), so > + * we can remain in virtual mode for this. > + */ > + bctr > +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) > /* > + * POWER8 > * Go to real mode to do the nap, as required by the architecture. > * Also, we need to be in real mode before setting hwthread_state, > * because as soon as we do that, another thread can switch
On Sun, Aug 06, 2017 at 03:02:40AM +1000, Nicholas Piggin wrote: > The hardware can execute stop in any context, and KVM does not > require real mode. This saves a switch to real-mode when going > idle. > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Acked-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> > --- > arch/powerpc/kernel/idle_book3s.S | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S > index 75746111e2c4..8ac366a51bb5 100644 > --- a/arch/powerpc/kernel/idle_book3s.S > +++ b/arch/powerpc/kernel/idle_book3s.S > @@ -141,7 +141,16 @@ pnv_powersave_common: > std r5,_CCR(r1) > std r1,PACAR1(r13) > > +BEGIN_FTR_SECTION > + /* > + * POWER9 does not require real mode to stop, and does not set > + * hwthread_state for KVM (threads don't share MMU context), so > + * we can remain in virtual mode for this. > + */ > + bctr > +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) > /* > + * POWER8 > * Go to real mode to do the nap, as required by the architecture. > * Also, we need to be in real mode before setting hwthread_state, > * because as soon as we do that, another thread can switch > -- > 2.11.0 >
diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index 75746111e2c4..8ac366a51bb5 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S @@ -141,7 +141,16 @@ pnv_powersave_common: std r5,_CCR(r1) std r1,PACAR1(r13) +BEGIN_FTR_SECTION + /* + * POWER9 does not require real mode to stop, and does not set + * hwthread_state for KVM (threads don't share MMU context), so + * we can remain in virtual mode for this. + */ + bctr +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) /* + * POWER8 * Go to real mode to do the nap, as required by the architecture. * Also, we need to be in real mode before setting hwthread_state, * because as soon as we do that, another thread can switch
The hardware can execute stop in any context, and KVM does not require real mode. This saves a switch to real-mode when going idle. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kernel/idle_book3s.S | 9 +++++++++ 1 file changed, 9 insertions(+)