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Re: [PATCH] spapr: avoid overhead of finding vhyp class in critical oper
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From: |
David Gibson |
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Subject: |
Re: [PATCH] spapr: avoid overhead of finding vhyp class in critical operations |
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Date: |
Mon, 26 Feb 2024 14:01:50 +1100 |
On Sat, Feb 24, 2024 at 05:33:59PM +1000, 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 <npiggin@gmail.com>
> ---
> 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?
Not one I'm aware of, unfortunately.
>
> 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) {
> - 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);
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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