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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

WARNING: multiple messages have this Message-ID (diff)
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 11:49:44 +0000	[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

  reply	other threads:[~2017-08-28 11:49 UTC|newest]

Thread overview: 38+ 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 ` Nicholas Piggin
2017-08-25  4:30 ` [PATCH v3 1/4] KVM: PPC: Book3S HV: POWER9 does not require secondary thread management Nicholas Piggin
2017-08-25  4:30   ` Nicholas Piggin
2017-08-28 11:49   ` Michael Ellerman [this message]
2017-08-28 11:49     ` Michael Ellerman
2017-08-29  0:13   ` Paul Mackerras
2017-08-29  0:13     ` Paul Mackerras
2017-08-31 11:36   ` [v3, " Michael Ellerman
2017-08-31 11:36     ` Michael Ellerman
2017-08-25  4:30 ` [PATCH v3 2/4] powerpc/64s: idle POWER9 can execute stop without a sync sequence Nicholas Piggin
2017-08-25  4:30   ` Nicholas Piggin
2017-08-29  0:11   ` Paul Mackerras
2017-08-29  0:11     ` Paul Mackerras
2017-08-29 10:30     ` Michael Ellerman
2017-08-29 10:30       ` Michael Ellerman
2017-08-31 11:36   ` [v3, " Michael Ellerman
2017-08-31 11:36     ` Michael Ellerman
2017-08-25  4:30 ` [PATCH v3 3/4] powerpc/64s: idle POWER9 can execute stop in virtual mode Nicholas Piggin
2017-08-25  4:30   ` Nicholas Piggin
2017-08-29  0:14   ` Paul Mackerras
2017-08-29  0:14     ` Paul Mackerras
2017-08-31 11:36   ` [v3, " Michael Ellerman
2017-08-31 11:36     ` [v3,3/4] " 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
2017-08-25  4:30   ` Nicholas Piggin
2017-08-29  0:20   ` Paul Mackerras
2017-08-29  0:20     ` Paul Mackerras
2017-08-29  1:39     ` Nicholas Piggin
2017-08-29  1:39       ` Nicholas Piggin
2017-08-30 11:25   ` Michael Ellerman
2017-08-30 11:25     ` Michael Ellerman
2017-08-30 12:10     ` Nicholas Piggin
2017-08-30 12:10       ` Nicholas Piggin
2017-09-01  9:39       ` Michael Ellerman
2017-09-01  9:39         ` Michael Ellerman
2017-09-20 13:56         ` Nicholas Piggin
2017-09-20 13:56           ` Nicholas Piggin

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