From: Fabiano Rosas <farosas@linux.ibm.com>
To: Nicholas Piggin <npiggin@gmail.com>, kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org, Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH v1 30/55] KVM: PPC: Book3S HV P9: Only execute mtSPR if the value changed
Date: Fri, 06 Aug 2021 17:45:19 -0300 [thread overview]
Message-ID: <875ywiti8w.fsf@linux.ibm.com> (raw)
In-Reply-To: <20210726035036.739609-31-npiggin@gmail.com>
Nicholas Piggin <npiggin@gmail.com> writes:
> Keep better track of the current SPR value in places where
> they are to be loaded with a new context, to reduce expensive
> mtSPR operations.
>
> -73 cycles (7354) POWER9 virt-mode NULL hcall
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
> ---
> arch/powerpc/kvm/book3s_hv.c | 64 ++++++++++++++++++++++--------------
> 1 file changed, 39 insertions(+), 25 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 0d97138e6fa4..56429b53f4dc 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -4009,19 +4009,28 @@ static void switch_pmu_to_host(struct kvm_vcpu *vcpu,
> }
> }
>
> -static void load_spr_state(struct kvm_vcpu *vcpu)
> +static void load_spr_state(struct kvm_vcpu *vcpu,
> + struct p9_host_os_sprs *host_os_sprs)
> {
> - mtspr(SPRN_DSCR, vcpu->arch.dscr);
> - mtspr(SPRN_IAMR, vcpu->arch.iamr);
> - mtspr(SPRN_PSPB, vcpu->arch.pspb);
> - mtspr(SPRN_FSCR, vcpu->arch.fscr);
> mtspr(SPRN_TAR, vcpu->arch.tar);
> mtspr(SPRN_EBBHR, vcpu->arch.ebbhr);
> mtspr(SPRN_EBBRR, vcpu->arch.ebbrr);
> mtspr(SPRN_BESCR, vcpu->arch.bescr);
> - mtspr(SPRN_TIDR, vcpu->arch.tid);
> - mtspr(SPRN_AMR, vcpu->arch.amr);
> - mtspr(SPRN_UAMOR, vcpu->arch.uamor);
> +
> + if (!cpu_has_feature(CPU_FTR_ARCH_31))
> + mtspr(SPRN_TIDR, vcpu->arch.tid);
> + if (host_os_sprs->iamr != vcpu->arch.iamr)
> + mtspr(SPRN_IAMR, vcpu->arch.iamr);
> + if (host_os_sprs->amr != vcpu->arch.amr)
> + mtspr(SPRN_AMR, vcpu->arch.amr);
> + if (vcpu->arch.uamor != 0)
> + mtspr(SPRN_UAMOR, vcpu->arch.uamor);
> + if (host_os_sprs->fscr != vcpu->arch.fscr)
> + mtspr(SPRN_FSCR, vcpu->arch.fscr);
> + if (host_os_sprs->dscr != vcpu->arch.dscr)
> + mtspr(SPRN_DSCR, vcpu->arch.dscr);
> + if (vcpu->arch.pspb != 0)
> + mtspr(SPRN_PSPB, vcpu->arch.pspb);
>
> /*
> * DAR, DSISR, and for nested HV, SPRGs must be set with MSR[RI]
> @@ -4036,28 +4045,31 @@ static void load_spr_state(struct kvm_vcpu *vcpu)
>
> static void store_spr_state(struct kvm_vcpu *vcpu)
> {
> - vcpu->arch.ctrl = mfspr(SPRN_CTRLF);
> -
> - vcpu->arch.iamr = mfspr(SPRN_IAMR);
> - vcpu->arch.pspb = mfspr(SPRN_PSPB);
> - vcpu->arch.fscr = mfspr(SPRN_FSCR);
> vcpu->arch.tar = mfspr(SPRN_TAR);
> vcpu->arch.ebbhr = mfspr(SPRN_EBBHR);
> vcpu->arch.ebbrr = mfspr(SPRN_EBBRR);
> vcpu->arch.bescr = mfspr(SPRN_BESCR);
> - vcpu->arch.tid = mfspr(SPRN_TIDR);
> +
> + if (!cpu_has_feature(CPU_FTR_ARCH_31))
> + vcpu->arch.tid = mfspr(SPRN_TIDR);
> + vcpu->arch.iamr = mfspr(SPRN_IAMR);
> vcpu->arch.amr = mfspr(SPRN_AMR);
> vcpu->arch.uamor = mfspr(SPRN_UAMOR);
> + vcpu->arch.fscr = mfspr(SPRN_FSCR);
> vcpu->arch.dscr = mfspr(SPRN_DSCR);
> + vcpu->arch.pspb = mfspr(SPRN_PSPB);
> +
> + vcpu->arch.ctrl = mfspr(SPRN_CTRLF);
> }
>
> static void save_p9_host_os_sprs(struct p9_host_os_sprs *host_os_sprs)
> {
> - host_os_sprs->dscr = mfspr(SPRN_DSCR);
> - host_os_sprs->tidr = mfspr(SPRN_TIDR);
> + if (!cpu_has_feature(CPU_FTR_ARCH_31))
> + host_os_sprs->tidr = mfspr(SPRN_TIDR);
> host_os_sprs->iamr = mfspr(SPRN_IAMR);
> host_os_sprs->amr = mfspr(SPRN_AMR);
> host_os_sprs->fscr = mfspr(SPRN_FSCR);
> + host_os_sprs->dscr = mfspr(SPRN_DSCR);
> }
>
> /* vcpu guest regs must already be saved */
> @@ -4066,18 +4078,20 @@ static void restore_p9_host_os_sprs(struct kvm_vcpu *vcpu,
> {
> mtspr(SPRN_SPRG_VDSO_WRITE, local_paca->sprg_vdso);
>
> - mtspr(SPRN_PSPB, 0);
> - mtspr(SPRN_UAMOR, 0);
> -
> - mtspr(SPRN_DSCR, host_os_sprs->dscr);
> - mtspr(SPRN_TIDR, host_os_sprs->tidr);
> - mtspr(SPRN_IAMR, host_os_sprs->iamr);
> -
> + if (!cpu_has_feature(CPU_FTR_ARCH_31))
> + mtspr(SPRN_TIDR, host_os_sprs->tidr);
> + if (host_os_sprs->iamr != vcpu->arch.iamr)
> + mtspr(SPRN_IAMR, host_os_sprs->iamr);
> + if (vcpu->arch.uamor != 0)
> + mtspr(SPRN_UAMOR, 0);
> if (host_os_sprs->amr != vcpu->arch.amr)
> mtspr(SPRN_AMR, host_os_sprs->amr);
> -
> if (host_os_sprs->fscr != vcpu->arch.fscr)
> mtspr(SPRN_FSCR, host_os_sprs->fscr);
> + if (host_os_sprs->dscr != vcpu->arch.dscr)
> + mtspr(SPRN_DSCR, host_os_sprs->dscr);
> + if (vcpu->arch.pspb != 0)
> + mtspr(SPRN_PSPB, 0);
>
> /* Save guest CTRL register, set runlatch to 1 */
> if (!(vcpu->arch.ctrl & 1))
> @@ -4169,7 +4183,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
> #endif
> mtspr(SPRN_VRSAVE, vcpu->arch.vrsave);
>
> - load_spr_state(vcpu);
> + load_spr_state(vcpu, &host_os_sprs);
>
> if (kvmhv_on_pseries()) {
> /*
next prev parent reply other threads:[~2021-08-06 20:46 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-26 3:49 [PATCH v1 00/55] KVM: PPC: Book3S HV P9: entry/exit optimisations Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 01/55] KVM: PPC: Book3S HV: Remove TM emulation from POWER7/8 path Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 02/55] KVM: PPC: Book3S HV P9: Fixes for TM softpatch interrupt Nicholas Piggin
2021-08-06 1:16 ` Michael Ellerman
2021-08-06 10:25 ` Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 03/55] KVM: PPC: Book3S HV: Sanitise vcpu registers in nested path Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 04/55] KVM: PPC: Book3S HV: Stop forwarding all HFUs to L1 Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 05/55] KVM: PPC: Book3S HV Nested: Reflect guest PMU in-use to L0 when guest SPRs are live Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 06/55] powerpc/64s: Remove WORT SPR from POWER9/10 Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 07/55] KMV: PPC: Book3S HV P9: Use set_dec to set decrementer to host Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 08/55] KVM: PPC: Book3S HV P9: Use host timer accounting to avoid decrementer read Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 09/55] KVM: PPC: Book3S HV P9: Use large decrementer for HDEC Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 10/55] KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 11/55] powerpc/time: add API for KVM to re-arm the host timer/decrementer Nicholas Piggin
2021-08-05 7:22 ` Christophe Leroy
2021-08-06 10:30 ` Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 12/55] KVM: PPC: Book3S HV: POWER10 enable HAIL when running radix guests Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 13/55] powerpc/64s: Keep AMOR SPR a constant ~0 at runtime Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 14/55] KVM: PPC: Book3S HV: Don't always save PMU for guest capable of nesting Nicholas Piggin
2021-08-06 7:34 ` Michael Ellerman
2021-08-06 10:32 ` Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 15/55] powerpc/64s: Always set PMU control registers to frozen/disabled when not in use Nicholas Piggin
2021-07-26 3:49 ` [PATCH v1 16/55] powerpc/64s: Implement PMU override command line option Nicholas Piggin
2021-08-06 7:33 ` Madhavan Srinivasan
2021-08-06 10:38 ` Nicholas Piggin
2021-08-11 12:46 ` Madhavan Srinivasan
2021-08-06 9:28 ` Athira Rajeev
2021-08-06 10:42 ` Nicholas Piggin
2021-08-11 10:54 ` Athira Rajeev
2021-07-26 3:49 ` [PATCH v1 17/55] KVM: PPC: Book3S HV P9: Implement PMU save/restore in C Nicholas Piggin
2021-08-09 3:03 ` Athira Rajeev
2021-08-13 4:24 ` Nicholas Piggin
2021-08-14 7:12 ` Athira Rajeev
2021-07-26 3:49 ` [PATCH v1 18/55] KVM: PPC: Book3S HV P9: Factor PMU save/load into context switch functions Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 19/55] KVM: PPC: Book3S HV P9: Demand fault PMU SPRs when marked not inuse Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 20/55] KVM: PPC: Book3S HV P9: Factor out yield_count increment Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 21/55] KVM: PPC: Book3S HV: CTRL SPR does not require read-modify-write Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 22/55] KVM: PPC: Book3S HV P9: Move SPRG restore to restore_p9_host_os_sprs Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 23/55] KVM: PPC: Book3S HV P9: Reduce mtmsrd instructions required to save host SPRs Nicholas Piggin
2021-07-26 6:57 ` kernel test robot
2021-07-26 7:01 ` kernel test robot
2021-07-26 3:50 ` [PATCH v1 24/55] KVM: PPC: Book3S HV P9: Improve mtmsrd scheduling by delaying MSR[EE] disable Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 25/55] KVM: PPC: Book3S HV P9: Add kvmppc_stop_thread to match kvmppc_start_thread Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 26/55] KVM: PPC: Book3S HV: Change dec_expires to be relative to guest timebase Nicholas Piggin
2021-08-07 23:17 ` Michael Ellerman
2021-07-26 3:50 ` [PATCH v1 27/55] KVM: PPC: Book3S HV P9: Move TB updates Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 28/55] KVM: PPC: Book3S HV P9: Optimise timebase reads Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 29/55] KVM: PPC: Book3S HV P9: Avoid SPR scoreboard stalls Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 30/55] KVM: PPC: Book3S HV P9: Only execute mtSPR if the value changed Nicholas Piggin
2021-08-06 20:45 ` Fabiano Rosas [this message]
2021-07-26 3:50 ` [PATCH v1 31/55] KVM: PPC: Book3S HV P9: Juggle SPR switching around Nicholas Piggin
2021-08-06 20:46 ` Fabiano Rosas
2021-07-26 3:50 ` [PATCH v1 32/55] KVM: PPC: Book3S HV P9: Move vcpu register save/restore into functions Nicholas Piggin
2021-08-06 20:49 ` Fabiano Rosas
2021-07-26 3:50 ` [PATCH v1 33/55] KVM: PPC: Book3S HV P9: Move host OS save/restore functions to built-in Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 34/55] KVM: PPC: Book3S HV P9: Move nested guest entry into its own function Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 35/55] KVM: PPC: Book3S HV P9: Move remaining SPR and MSR access into low level entry Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 36/55] KVM: PPC: Book3S HV P9: Implement TM fastpath for guest entry/exit Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 37/55] KVM: PPC: Book3S HV P9: Switch PMU to guest as late as possible Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 38/55] KVM: PPC: Book3S HV P9: Restrict DSISR canary workaround to processors that require it Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 39/55] KVM: PPC: Book3S HV P9: More SPR speed improvements Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 40/55] KVM: PPC: Book3S HV P9: Demand fault EBB facility registers Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 41/55] KVM: PPC: Book3S HV P9: Demand fault TM " Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 42/55] KVM: PPC: Book3S HV P9: Use Linux SPR save/restore to manage some host SPRs Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 43/55] KVM: PPC: Book3S HV P9: Comment and fix MMU context switching code Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 44/55] KVM: PPC: Book3S HV P9: Test dawr_enabled() before saving host DAWR SPRs Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 45/55] KVM: PPC: Book3S HV P9: Don't restore PSSCR if not needed Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 46/55] KVM: PPC: Book3S HV P9: Avoid tlbsync sequence on radix guest exit Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 47/55] KVM: PPC: Book3S HV Nested: Avoid extra mftb() in nested entry Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 48/55] KVM: PPC: Book3S HV P9: Improve mfmsr performance on entry Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 49/55] KVM: PPC: Book3S HV P9: Optimise hash guest SLB saving Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 50/55] KVM: PPC: Book3S HV P9: Add unlikely annotation for !mmu_ready Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 51/55] KVM: PPC: Book3S HV P9: Avoid cpu_in_guest atomics on entry and exit Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 52/55] KVM: PPC: Book3S HV P9: Remove most of the vcore logic Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 53/55] KVM: PPC: Book3S HV P9: Tidy kvmppc_create_dtl_entry Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 54/55] KVM: PPC: Book3S HV P9: Stop using vc->dpdes Nicholas Piggin
2021-07-26 3:50 ` [PATCH v1 55/55] KVM: PPC: Book3S HV P9: Remove subcore HMI handling Nicholas Piggin
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