From: Paul Mackerras <paulus@ozlabs.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org
Subject: Re: [PATCH v2 12/14] KVM: PPC: Book3S HV: POWER9 can execute stop without a sync sequence
Date: Thu, 24 Aug 2017 20:27:35 +1000 [thread overview]
Message-ID: <20170824102735.GI27401@fergus.ozlabs.ibm.com> (raw)
In-Reply-To: <20170811163912.28783-13-npiggin@gmail.com>
On Sat, Aug 12, 2017 at 02:39:10AM +1000, Nicholas Piggin wrote:
> Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 24 ++++++++++++------------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 3e024fd71fe8..edb47738a686 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -2527,7 +2527,17 @@ BEGIN_FTR_SECTION
> END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
>
> kvm_nap_sequence: /* desired LPCR value in r5 */
> -BEGIN_FTR_SECTION
> +BEGIN_FTR_SECTION /* nap sequence */
> + mtspr SPRN_LPCR,r5
> + isync
> + li r0, 0
> + std r0, HSTATE_SCRATCH0(r13)
> + ptesync
> + ld r0, HSTATE_SCRATCH0(r13)
> +1: cmpd r0, r0
> + bne 1b
> + nap
> +FTR_SECTION_ELSE /* stop sequence */
> /*
> * PSSCR bits: exit criterion = 1 (wakeup based on LPCR at sreset)
> * enable state loss = 1 (allow SMT mode switch)
> @@ -2539,18 +2549,8 @@ BEGIN_FTR_SECTION
> li r4, LPCR_PECE_HVEE@higher
> sldi r4, r4, 32
> or r5, r5, r4
> -END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
> mtspr SPRN_LPCR,r5
> - isync
> - li r0, 0
> - std r0, HSTATE_SCRATCH0(r13)
> - ptesync
> - ld r0, HSTATE_SCRATCH0(r13)
> -1: cmpd r0, r0
> - bne 1b
> -BEGIN_FTR_SECTION
> - nap
> -FTR_SECTION_ELSE
> +
> PPC_STOP
> ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
> b .
> --
> 2.13.3
Currently we never get to kvm_nap_sequence on POWER9 because we are
always running one vcpu per vcore, so I haven't worried about this
code too much. In future we might need this for running HPT guests on
a radix host, though.
Paul.
next prev parent reply other threads:[~2017-08-24 10:27 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-11 16:38 [PATCH v2 00/14] idle and soft-irq improvements and POWER9 idle optimisation Nicholas Piggin
2017-08-11 16:38 ` [PATCH v2 01/14] powerpc/64s: masked interrupt avoid branch Nicholas Piggin
2017-08-24 12:37 ` [v2,01/14] " Michael Ellerman
2017-08-11 16:39 ` [PATCH v2 02/14] powerpc/64s: masked interrupt avoid instruction Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 03/14] powerpc/64s: masked interrupt returns to kernel so avoid r13 restore Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 04/14] powerpc/64: cleanup __check_irq_replay Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 05/14] powerpc/64s: irq replay merge HV and non-HV paths for doorbell replay Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 06/14] powerpc/64s: irq replay external use the HV handler in HV mode on POWER9 Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 07/14] powerpc/64: remove redundant instruction in interrupt replay Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 08/14] powerpc/64s: irq replay remove spurious irq reason Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 09/14] powerpc/64: runlatch CTRL[RUN] set optimisation Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 10/14] KVM: PPC: Book3S HV: POWER9 does not require secondary thread management Nicholas Piggin
2017-08-24 9:34 ` Paul Mackerras
2017-08-24 12:45 ` Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 11/14] powerpc/64s: idle POWER9 can execute stop without a sync sequence Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 12/14] KVM: PPC: Book3S HV: " Nicholas Piggin
2017-08-24 10:27 ` Paul Mackerras [this message]
2017-08-24 12:53 ` Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 13/14] powerpc/64s: idle POWER9 can execute stop in virtual mode Nicholas Piggin
2017-08-11 16:39 ` [PATCH v2 14/14] powerpc/64s: idle ESL=0 stop can avoid MSR and save/restore overhead Nicholas Piggin
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