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Tue, 12 Mar 2024 06:38:03 +0000 (GMT) Message-ID: Date: Tue, 12 Mar 2024 12:08:02 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] spapr: avoid overhead of finding vhyp class in critical operations Content-Language: en-US To: Nicholas Piggin , qemu-ppc@nongnu.org Cc: qemu-devel@nongnu.org, BALATON Zoltan , David Gibson , Daniel Henrique Barboza References: <20240224073359.1025835-1-npiggin@gmail.com> From: Harsh Prateek Bora In-Reply-To: <20240224073359.1025835-1-npiggin@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: V2qx_0hOABw1_wpKRcRa4o2G90HivMp2 X-Proofpoint-GUID: 42MRTp-0glqbpyYR-ST6JoSVDPXIWDfu X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-03-12_05,2024-03-11_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 suspectscore=0 spamscore=0 phishscore=0 priorityscore=1501 clxscore=1015 mlxscore=0 malwarescore=0 adultscore=0 impostorscore=0 mlxlogscore=999 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2403120050 Received-SPF: pass client-ip=148.163.156.1; envelope-from=harshpb@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi Nick, One minor comment below: On 2/24/24 13:03, Nicholas Piggin wrote: > PPC_VIRTUAL_HYPERVISOR_GET_CLASS is used in critical operations like > interrupts and TLB misses and is quite costly. Running the > kvm-unit-tests sieve program with radix MMU enabled thrashes the TCG > TLB and spends a lot of time in TLB and page table walking code. The > test takes 67 seconds to complete with a lot of time being spent in > code related to finding the vhyp class: > > 12.01% [.] g_str_hash > 8.94% [.] g_hash_table_lookup > 8.06% [.] object_class_dynamic_cast > 6.21% [.] address_space_ldq > 4.94% [.] __strcmp_avx2 > 4.28% [.] tlb_set_page_full > 4.08% [.] address_space_translate_internal > 3.17% [.] object_class_dynamic_cast_assert > 2.84% [.] ppc_radix64_xlate > > Keep a pointer to the class and avoid this lookup. This reduces the > execution time to 40 seconds. > > Signed-off-by: Nicholas Piggin > --- > This feels a bit ugly, but the performance problem of looking up the > class in fast paths can't be ignored. Is there a "nicer" way to get the > same result? > > Thanks, > Nick > > target/ppc/cpu.h | 3 ++- > target/ppc/mmu-book3s-v3.h | 4 +--- > hw/ppc/pegasos2.c | 1 + > target/ppc/cpu_init.c | 9 +++------ > target/ppc/excp_helper.c | 16 ++++------------ > target/ppc/kvm.c | 4 +--- > target/ppc/mmu-hash64.c | 16 ++++------------ > target/ppc/mmu-radix64.c | 4 +--- > 8 files changed, 17 insertions(+), 40 deletions(-) > > diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h > index ec14574d14..eb85d9aa71 100644 > --- a/target/ppc/cpu.h > +++ b/target/ppc/cpu.h > @@ -1437,6 +1437,7 @@ struct ArchCPU { > int vcpu_id; > uint32_t compat_pvr; > PPCVirtualHypervisor *vhyp; > + PPCVirtualHypervisorClass *vhyp_class; > void *machine_data; > int32_t node_id; /* NUMA node this CPU belongs to */ > PPCHash64Options *hash64_opts; > @@ -1535,7 +1536,7 @@ DECLARE_OBJ_CHECKERS(PPCVirtualHypervisor, PPCVirtualHypervisorClass, > > static inline bool vhyp_cpu_in_nested(PowerPCCPU *cpu) > { > - return PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp)->cpu_in_nested(cpu); > + return cpu->vhyp_class->cpu_in_nested(cpu); > } > #endif /* CONFIG_USER_ONLY */ > > diff --git a/target/ppc/mmu-book3s-v3.h b/target/ppc/mmu-book3s-v3.h > index 674377a19e..f3f7993958 100644 > --- a/target/ppc/mmu-book3s-v3.h > +++ b/target/ppc/mmu-book3s-v3.h > @@ -108,9 +108,7 @@ static inline hwaddr ppc_hash64_hpt_mask(PowerPCCPU *cpu) > uint64_t base; > > if (cpu->vhyp) { All the checks for cpu->vhyp needs to be changed to check for cpu->vhyp_class now, for all such instances. With that, Reviewed-by: Harsh Prateek Bora > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - return vhc->hpt_mask(cpu->vhyp); > + return cpu->vhyp_class->hpt_mask(cpu->vhyp); > } > if (cpu->env.mmu_model == POWERPC_MMU_3_00) { > ppc_v3_pate_t pate; > diff --git a/hw/ppc/pegasos2.c b/hw/ppc/pegasos2.c > index 04d6decb2b..c22e8b336d 100644 > --- a/hw/ppc/pegasos2.c > +++ b/hw/ppc/pegasos2.c > @@ -400,6 +400,7 @@ static void pegasos2_machine_reset(MachineState *machine, ShutdownCause reason) > machine->fdt = fdt; > > pm->cpu->vhyp = PPC_VIRTUAL_HYPERVISOR(machine); > + pm->cpu->vhyp_class = PPC_VIRTUAL_HYPERVISOR_GET_CLASS(pm->cpu->vhyp); > } > > enum pegasos2_rtas_tokens { > diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c > index 9bccddb350..63d0094024 100644 > --- a/target/ppc/cpu_init.c > +++ b/target/ppc/cpu_init.c > @@ -6631,6 +6631,7 @@ void cpu_ppc_set_vhyp(PowerPCCPU *cpu, PPCVirtualHypervisor *vhyp) > CPUPPCState *env = &cpu->env; > > cpu->vhyp = vhyp; > + cpu->vhyp_class = PPC_VIRTUAL_HYPERVISOR_GET_CLASS(vhyp); > > /* > * With a virtual hypervisor mode we never allow the CPU to go > @@ -7224,9 +7225,7 @@ static void ppc_cpu_exec_enter(CPUState *cs) > PowerPCCPU *cpu = POWERPC_CPU(cs); > > if (cpu->vhyp) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - vhc->cpu_exec_enter(cpu->vhyp, cpu); > + cpu->vhyp_class->cpu_exec_enter(cpu->vhyp, cpu); > } > } > > @@ -7235,9 +7234,7 @@ static void ppc_cpu_exec_exit(CPUState *cs) > PowerPCCPU *cpu = POWERPC_CPU(cs); > > if (cpu->vhyp) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - vhc->cpu_exec_exit(cpu->vhyp, cpu); > + cpu->vhyp_class->cpu_exec_exit(cpu->vhyp, cpu); > } > } > #endif /* CONFIG_TCG */ > diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c > index 98952de267..445350488c 100644 > --- a/target/ppc/excp_helper.c > +++ b/target/ppc/excp_helper.c > @@ -840,9 +840,7 @@ static void powerpc_excp_7xx(PowerPCCPU *cpu, int excp) > * HV mode, we need to keep hypercall support. > */ > if (lev == 1 && cpu->vhyp) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - vhc->hypercall(cpu->vhyp, cpu); > + cpu->vhyp_class->hypercall(cpu->vhyp, cpu); > powerpc_reset_excp_state(cpu); > return; > } > @@ -1012,9 +1010,7 @@ static void powerpc_excp_74xx(PowerPCCPU *cpu, int excp) > * HV mode, we need to keep hypercall support. > */ > if (lev == 1 && cpu->vhyp) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - vhc->hypercall(cpu->vhyp, cpu); > + cpu->vhyp_class->hypercall(cpu->vhyp, cpu); > powerpc_reset_excp_state(cpu); > return; > } > @@ -1534,9 +1530,7 @@ static void powerpc_excp_books(PowerPCCPU *cpu, int excp) > > /* "PAPR mode" built-in hypercall emulation */ > if (lev == 1 && books_vhyp_handles_hcall(cpu)) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - vhc->hypercall(cpu->vhyp, cpu); > + cpu->vhyp_class->hypercall(cpu->vhyp, cpu); > powerpc_reset_excp_state(cpu); > return; > } > @@ -1677,10 +1671,8 @@ static void powerpc_excp_books(PowerPCCPU *cpu, int excp) > } > > if ((new_msr & MSR_HVB) && books_vhyp_handles_hv_excp(cpu)) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > /* Deliver interrupt to L1 by returning from the H_ENTER_NESTED call */ > - vhc->deliver_hv_excp(cpu, excp); > + cpu->vhyp_class->deliver_hv_excp(cpu, excp); > > powerpc_reset_excp_state(cpu); > > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c > index 26fa9d0575..5b5b96ab6b 100644 > --- a/target/ppc/kvm.c > +++ b/target/ppc/kvm.c > @@ -862,9 +862,7 @@ int kvmppc_put_books_sregs(PowerPCCPU *cpu) > sregs.pvr = env->spr[SPR_PVR]; > > if (cpu->vhyp) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - sregs.u.s.sdr1 = vhc->encode_hpt_for_kvm_pr(cpu->vhyp); > + sregs.u.s.sdr1 = cpu->vhyp_class->encode_hpt_for_kvm_pr(cpu->vhyp); > } else { > sregs.u.s.sdr1 = env->spr[SPR_SDR1]; > } > diff --git a/target/ppc/mmu-hash64.c b/target/ppc/mmu-hash64.c > index d645c0bb94..196b4b2a48 100644 > --- a/target/ppc/mmu-hash64.c > +++ b/target/ppc/mmu-hash64.c > @@ -516,9 +516,7 @@ const ppc_hash_pte64_t *ppc_hash64_map_hptes(PowerPCCPU *cpu, > const ppc_hash_pte64_t *hptes; > > if (cpu->vhyp) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - return vhc->map_hptes(cpu->vhyp, ptex, n); > + return cpu->vhyp_class->map_hptes(cpu->vhyp, ptex, n); > } > base = ppc_hash64_hpt_base(cpu); > > @@ -538,9 +536,7 @@ void ppc_hash64_unmap_hptes(PowerPCCPU *cpu, const ppc_hash_pte64_t *hptes, > hwaddr ptex, int n) > { > if (cpu->vhyp) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - vhc->unmap_hptes(cpu->vhyp, hptes, ptex, n); > + cpu->vhyp_class->unmap_hptes(cpu->vhyp, hptes, ptex, n); > return; > } > > @@ -820,9 +816,7 @@ static void ppc_hash64_set_r(PowerPCCPU *cpu, hwaddr ptex, uint64_t pte1) > hwaddr base, offset = ptex * HASH_PTE_SIZE_64 + HPTE64_DW1_R; > > if (cpu->vhyp) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - vhc->hpte_set_r(cpu->vhyp, ptex, pte1); > + cpu->vhyp_class->hpte_set_r(cpu->vhyp, ptex, pte1); > return; > } > base = ppc_hash64_hpt_base(cpu); > @@ -837,9 +831,7 @@ static void ppc_hash64_set_c(PowerPCCPU *cpu, hwaddr ptex, uint64_t pte1) > hwaddr base, offset = ptex * HASH_PTE_SIZE_64 + HPTE64_DW1_C; > > if (cpu->vhyp) { > - PPCVirtualHypervisorClass *vhc = > - PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - vhc->hpte_set_c(cpu->vhyp, ptex, pte1); > + cpu->vhyp_class->hpte_set_c(cpu->vhyp, ptex, pte1); > return; > } > base = ppc_hash64_hpt_base(cpu); > diff --git a/target/ppc/mmu-radix64.c b/target/ppc/mmu-radix64.c > index 5823e039e6..496ba87a95 100644 > --- a/target/ppc/mmu-radix64.c > +++ b/target/ppc/mmu-radix64.c > @@ -677,9 +677,7 @@ static bool ppc_radix64_xlate_impl(PowerPCCPU *cpu, vaddr eaddr, > > /* Get Partition Table */ > if (cpu->vhyp) { > - PPCVirtualHypervisorClass *vhc; > - vhc = PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp); > - if (!vhc->get_pate(cpu->vhyp, cpu, lpid, &pate)) { > + if (!cpu->vhyp_class->get_pate(cpu->vhyp, cpu, lpid, &pate)) { > if (guest_visible) { > ppc_radix64_raise_hsi(cpu, access_type, eaddr, eaddr, > DSISR_R_BADCONFIG);