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Commit 72b0d51d authored Aug 25, 2017 by Nicholas Piggin Committed by Michael Ellerman Aug 29, 2017

powerpc/64s: idle POWER9 can execute stop in virtual mode



The hardware can execute stop in any context, and KVM does not
require real mode because siblings do not share MMU state. This
saves a switch to real-mode when going idle.

Acked-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

parent 65dbbe81

arch/powerpc/kernel/idle_book3s.S

+9 −0

Original line number	Diff line number	Diff line
		@@ -195,7 +195,16 @@ pnv_powersave_common:
		std r5,_CCR(r1)
		std r1,PACAR1(r13)

		BEGIN_FTR_SECTION
		/*
		* POWER9 does not require real mode to stop, and presently 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