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[115.64.153.41]) by smtp.gmail.com with ESMTPSA id 130sm15557223pfz.77.2021.10.04.09.01.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Oct 2021 09:01:02 -0700 (PDT) From: Nicholas Piggin To: kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: Nicholas Piggin Subject: [PATCH v3 00/52] KVM: PPC: Book3S HV P9: entry/exit optimisations Date: Tue, 5 Oct 2021 01:59:57 +1000 Message-Id: <20211004160049.1338837-1-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org This reduces radix guest full entry/exit latency on POWER9 and POWER10 by 2x. Nested HV guests should see smaller improvements in their L1 entry/exit, but this is also combined with most L0 speedups also applying to nested entry. nginx localhost throughput test in a SMP nested guest is improved about 10% (in a direct guest it doesn't change much because it uses XIVE for IPIs) when L0 and L1 are patched. It does this in several main ways: - Rearrange code to optimise SPR accesses. Mainly, avoid scoreboard stalls. - Test SPR values to avoid mtSPRs where possible. mtSPRs are expensive. - Reduce mftb. mftb is expensive. - Demand fault certain facilities to avoid saving and/or restoring them (at the cost of fault when they are used, but this is mitigated over a number of entries, like the facilities when context switching processes). PM, TM, and EBB so far. - Defer some sequences that are made just in case a guest is interrupted in the middle of a critical section to the case where the guest is scheduled on a different CPU, rather than every time (at the cost of an extra IPI in this case). Namely the tlbsync sequence for radix with GTSE, which is very expensive. - Reduce locking, barriers, atomics related to the vcpus-per-vcore > 1 handling that the P9 path does not require. Changes since v2: - Rebased, several patches from the series were merged in the previous merge window. - Fixed some compile errors noticed by kernel test robot. - Added RB from Athira for the PMU stuff (thanks!) - Split TIDR ftr check (patch 2) out into its own patch. - Added a missed license tag on new file. Changes since v1: - Verified DPDES changes still work with msgsndp SMT emulation. - Fixed HMI handling bug. - Split softpatch handling fixes into smaller pieces. - Rebased with Fabiano's latest HV sanitising patches. - Fix TM demand faulting bug causing nested guest TM tests to TM Bad Thing the host in rare cases. - Re-name new "pmu=" command line option to "pmu_override=" and update documentation wording. - Add default=y config option rather than unconditionally removing the L0 nested PMU workaround. - Remove unnecessary MSR[RI] updates in entry/exit. Down to about 4700 cycles now. - Another bugfix from Alexey's testing. Changes since RFC: - Rebased with Fabiano's HV sanitising patches at the front. - Several demand faulting bug fixes mostly relating to nested guests. - Removed facility demand-faulting from L0 nested entry/exit handler. Demand faulting is still done in the L1, but not the L0. The reason is to reduce complexity (although it's only a small amount of complexity), reduce demand faulting overhead that may require several Thanks, Nick Nicholas Piggin (52): powerpc/64s: Remove WORT SPR from POWER9/10 (take 2) powerpc/64s: guard optional TIDR SPR with CPU ftr test KMV: PPC: Book3S HV P9: Use set_dec to set decrementer to host KVM: PPC: Book3S HV P9: Use host timer accounting to avoid decrementer read KVM: PPC: Book3S HV P9: Use large decrementer for HDEC KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit powerpc/time: add API for KVM to re-arm the host timer/decrementer KVM: PPC: Book3S HV: POWER10 enable HAIL when running radix guests powerpc/64s: Keep AMOR SPR a constant ~0 at runtime KVM: PPC: Book3S HV: Don't always save PMU for guest capable of nesting powerpc/64s: Always set PMU control registers to frozen/disabled when not in use powerpc/64s: Implement PMU override command line option KVM: PPC: Book3S HV P9: Implement PMU save/restore in C KVM: PPC: Book3S HV P9: Factor PMU save/load into context switch functions KVM: PPC: Book3S HV P9: Demand fault PMU SPRs when marked not inuse KVM: PPC: Book3S HV P9: Factor out yield_count increment KVM: PPC: Book3S HV: CTRL SPR does not require read-modify-write KVM: PPC: Book3S HV P9: Move SPRG restore to restore_p9_host_os_sprs KVM: PPC: Book3S HV P9: Reduce mtmsrd instructions required to save host SPRs KVM: PPC: Book3S HV P9: Improve mtmsrd scheduling by delaying MSR[EE] disable KVM: PPC: Book3S HV P9: Add kvmppc_stop_thread to match kvmppc_start_thread KVM: PPC: Book3S HV: Change dec_expires to be relative to guest timebase KVM: PPC: Book3S HV P9: Move TB updates KVM: PPC: Book3S HV P9: Optimise timebase reads KVM: PPC: Book3S HV P9: Avoid SPR scoreboard stalls KVM: PPC: Book3S HV P9: Only execute mtSPR if the value changed KVM: PPC: Book3S HV P9: Juggle SPR switching around KVM: PPC: Book3S HV P9: Move vcpu register save/restore into functions KVM: PPC: Book3S HV P9: Move host OS save/restore functions to built-in KVM: PPC: Book3S HV P9: Move nested guest entry into its own function KVM: PPC: Book3S HV P9: Move remaining SPR and MSR access into low level entry KVM: PPC: Book3S HV P9: Implement TM fastpath for guest entry/exit KVM: PPC: Book3S HV P9: Switch PMU to guest as late as possible KVM: PPC: Book3S HV P9: Restrict DSISR canary workaround to processors that require it KVM: PPC: Book3S HV P9: More SPR speed improvements KVM: PPC: Book3S HV P9: Demand fault EBB facility registers KVM: PPC: Book3S HV P9: Demand fault TM facility registers KVM: PPC: Book3S HV P9: Use Linux SPR save/restore to manage some host SPRs KVM: PPC: Book3S HV P9: Comment and fix MMU context switching code KVM: PPC: Book3S HV P9: Test dawr_enabled() before saving host DAWR SPRs KVM: PPC: Book3S HV P9: Don't restore PSSCR if not needed KVM: PPC: Book3S HV P9: Avoid tlbsync sequence on radix guest exit KVM: PPC: Book3S HV Nested: Avoid extra mftb() in nested entry KVM: PPC: Book3S HV P9: Improve mfmsr performance on entry KVM: PPC: Book3S HV P9: Optimise hash guest SLB saving KVM: PPC: Book3S HV P9: Avoid changing MSR[RI] in entry and exit KVM: PPC: Book3S HV P9: Add unlikely annotation for !mmu_ready KVM: PPC: Book3S HV P9: Avoid cpu_in_guest atomics on entry and exit KVM: PPC: Book3S HV P9: Remove most of the vcore logic KVM: PPC: Book3S HV P9: Tidy kvmppc_create_dtl_entry KVM: PPC: Book3S HV P9: Stop using vc->dpdes KVM: PPC: Book3S HV P9: Remove subcore HMI handling .../admin-guide/kernel-parameters.txt | 8 + arch/powerpc/include/asm/asm-prototypes.h | 5 - arch/powerpc/include/asm/kvm_asm.h | 1 + arch/powerpc/include/asm/kvm_book3s.h | 6 + arch/powerpc/include/asm/kvm_book3s_64.h | 5 +- arch/powerpc/include/asm/kvm_host.h | 7 +- arch/powerpc/include/asm/kvm_ppc.h | 1 + arch/powerpc/include/asm/switch_to.h | 3 + arch/powerpc/include/asm/time.h | 19 +- arch/powerpc/kernel/cpu_setup_power.c | 12 +- arch/powerpc/kernel/dt_cpu_ftrs.c | 8 +- arch/powerpc/kernel/process.c | 34 + arch/powerpc/kernel/time.c | 54 +- arch/powerpc/kvm/Kconfig | 15 + arch/powerpc/kvm/book3s_64_entry.S | 11 +- arch/powerpc/kvm/book3s_64_mmu_radix.c | 4 + arch/powerpc/kvm/book3s_hv.c | 836 +++++++++--------- arch/powerpc/kvm/book3s_hv.h | 42 + arch/powerpc/kvm/book3s_hv_builtin.c | 2 + arch/powerpc/kvm/book3s_hv_hmi.c | 7 +- arch/powerpc/kvm/book3s_hv_interrupts.S | 13 +- arch/powerpc/kvm/book3s_hv_nested.c | 8 +- arch/powerpc/kvm/book3s_hv_p9_entry.c | 821 ++++++++++++++--- arch/powerpc/kvm/book3s_hv_ras.c | 54 ++ arch/powerpc/kvm/book3s_hv_rmhandlers.S | 73 +- arch/powerpc/mm/book3s64/radix_pgtable.c | 15 - arch/powerpc/perf/core-book3s.c | 35 + arch/powerpc/platforms/powernv/idle.c | 9 +- arch/powerpc/xmon/xmon.c | 10 +- 29 files changed, 1459 insertions(+), 659 deletions(-) create mode 100644 arch/powerpc/kvm/book3s_hv.h