KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit

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mftb is serialising (dispatch next-to-complete) so it is heavy weight
for a mfspr. Avoid reading it multiple times in the entry or exit paths.
A small number of cycles delay to timers is tolerable.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-7-npiggin@gmail.com

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Nicholas Piggin 2021-11-23 19:51:44 +10:00 • committed by Michael Ellerman

parent 9581991a60

commit 34bf08a207

2 changed files with 5 additions and 4 deletions

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4

arch/powerpc/kvm/book3s_hv.c

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5

arch/powerpc/kvm/book3s_hv_p9_entry.c

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