KVM: PPC: Book3S HV: POWER9 does not require secondary thread management

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POWER9 CPUs have independent MMU contexts per thread, so KVM does not
need to quiesce secondary threads, so the hwthread_req/hwthread_state
protocol does not have to be used. So patch it away on POWER9, and patch
away the branch from the Linux idle wakeup to kvm_start_guest that is
never used.

Add a warning and error out of kvmppc_grab_hwthread in case it is ever
called on POWER9.

This avoids a hwsync in the idle wakeup path on POWER9.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
[mpe: Use WARN(...) instead of WARN_ON()/pr_err(...)]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

...

This commit is contained in:

Nicholas Piggin 2017-08-25 14:30:33 +10:00 • committed by Michael Ellerman

parent 94171b19c3

commit 94a04bc25a

4 changed files with 48 additions and 12 deletions

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4

arch/powerpc/include/asm/kvm_book3s_asm.h

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35

arch/powerpc/kernel/idle_book3s.S

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13

arch/powerpc/kvm/book3s_hv.c

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8

arch/powerpc/kvm/book3s_hv_rmhandlers.S

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