From: Michael Ellerman <mpe@ellerman•id.au>
To: Nicholas Piggin <npiggin@gmail•com>,
linuxppc-dev@lists•ozlabs.org, Paul Mackerras <paulus@samba•org>
Cc: kvm-ppc@vger•kernel.org, Nicholas Piggin <npiggin@gmail•com>
Subject: Re: [PATCH v3 1/4] KVM: PPC: Book3S HV: POWER9 does not require secondary thread management
Date: Mon, 28 Aug 2017 21:49:44 +1000 [thread overview]
Message-ID: <877exnvrmv.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20170825043036.18236-2-npiggin@gmail.com>
Nicholas Piggin <npiggin@gmail•com> writes:
> 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>
> ---
> arch/powerpc/include/asm/kvm_book3s_asm.h | 4 ++++
> arch/powerpc/kernel/idle_book3s.S | 35 +++++++++++++++++++++----------
> arch/powerpc/kvm/book3s_hv.c | 14 ++++++++++++-
> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 8 +++++++
> 4 files changed, 49 insertions(+), 12 deletions(-)
Paulus do you mind acking this and I'll put it in my ppc-kvm topic
branch.
cheers
next prev parent reply other threads:[~2017-08-28 11:49 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-25 4:30 [PATCH v3 0/4] powerpc/64s: idle POWER9 stop improvements Nicholas Piggin
2017-08-25 4:30 ` [PATCH v3 1/4] KVM: PPC: Book3S HV: POWER9 does not require secondary thread management Nicholas Piggin
2017-08-28 11:49 ` Michael Ellerman [this message]
2017-08-29 0:13 ` Paul Mackerras
2017-08-31 11:36 ` [v3, " Michael Ellerman
2017-08-25 4:30 ` [PATCH v3 2/4] powerpc/64s: idle POWER9 can execute stop without a sync sequence Nicholas Piggin
2017-08-29 0:11 ` Paul Mackerras
2017-08-29 10:30 ` Michael Ellerman
2017-08-31 11:36 ` [v3, " Michael Ellerman
2017-08-25 4:30 ` [PATCH v3 3/4] powerpc/64s: idle POWER9 can execute stop in virtual mode Nicholas Piggin
2017-08-29 0:14 ` Paul Mackerras
2017-08-31 11:36 ` [v3, " Michael Ellerman
2017-08-25 4:30 ` [PATCH v3 4/4] powerpc/64s: idle ESL=0 stop can avoid MSR and save/restore overhead Nicholas Piggin
2017-08-29 0:20 ` Paul Mackerras
2017-08-29 1:39 ` Nicholas Piggin
2017-08-30 11:25 ` Michael Ellerman
2017-08-30 12:10 ` Nicholas Piggin
2017-09-01 9:39 ` Michael Ellerman
2017-09-20 13:56 ` Nicholas Piggin
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