From: "Cédric Le Goater" <clg@kaod.org>
To: Nicholas Piggin <npiggin@gmail.com>, kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 16/37] KVM: PPC: Book3S HV P9: Stop handling hcalls in real-mode in the P9 path
Date: Thu, 25 Feb 2021 14:51:57 +0000 [thread overview]
Message-ID: <47ae7b2f-9356-6cff-da38-142eaea773ca@kaod.org> (raw)
In-Reply-To: <20210225134652.2127648-17-npiggin@gmail.com>
On 2/25/21 2:46 PM, Nicholas Piggin wrote:
> In the interest of minimising the amount of code that is run in
> "real-mode", don't handle hcalls in real mode in the P9 path.
>
> POWER8 and earlier are much more expensive to exit from HV real mode
> and switch to host mode, because on those processors HV interrupts get
> to the hypervisor with the MMU off, and the other threads in the core
> need to be pulled out of the guest, and SLBs all need to be saved,
> ERATs invalidated, and host SLB reloaded before the MMU is re-enabled
> in host mode. Hash guests also require a lot of hcalls to run. The
> XICS interrupt controller requires hcalls to run.
>
> By contrast, POWER9 has independent thread switching, and in radix mode
> the hypervisor is already in a host virtual memory mode when the HV
> interrupt is taken. Radix + xive guests don't need hcalls to handle
> interrupts or manage translations.
>
> So it's much less important to handle hcalls in real mode in P9.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> arch/powerpc/include/asm/kvm_ppc.h | 5 +++++
> arch/powerpc/kvm/book3s_hv.c | 25 ++++++++++++++++++++++---
> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 5 +++++
> arch/powerpc/kvm/book3s_xive.c | 25 +++++++++++++++++++++++++
> 4 files changed, 57 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
> index 73b1ca5a6471..db6646c2ade2 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -607,6 +607,7 @@ extern void kvmppc_free_pimap(struct kvm *kvm);
> extern int kvmppc_xics_rm_complete(struct kvm_vcpu *vcpu, u32 hcall);
> extern void kvmppc_xics_free_icp(struct kvm_vcpu *vcpu);
> extern int kvmppc_xics_hcall(struct kvm_vcpu *vcpu, u32 cmd);
> +extern int kvmppc_xive_xics_hcall(struct kvm_vcpu *vcpu, u32 req);
> extern u64 kvmppc_xics_get_icp(struct kvm_vcpu *vcpu);
> extern int kvmppc_xics_set_icp(struct kvm_vcpu *vcpu, u64 icpval);
> extern int kvmppc_xics_connect_vcpu(struct kvm_device *dev,
> @@ -639,6 +640,8 @@ static inline int kvmppc_xics_enabled(struct kvm_vcpu *vcpu)
> static inline void kvmppc_xics_free_icp(struct kvm_vcpu *vcpu) { }
> static inline int kvmppc_xics_hcall(struct kvm_vcpu *vcpu, u32 cmd)
> { return 0; }
> +static inline int kvmppc_xive_xics_hcall(struct kvm_vcpu *vcpu, u32 req)
> + { return 0; }
> #endif
>
> #ifdef CONFIG_KVM_XIVE
> @@ -673,6 +676,7 @@ extern int kvmppc_xive_set_irq(struct kvm *kvm, int irq_source_id, u32 irq,
> int level, bool line_status);
> extern void kvmppc_xive_push_vcpu(struct kvm_vcpu *vcpu);
> extern void kvmppc_xive_pull_vcpu(struct kvm_vcpu *vcpu);
> +extern void kvmppc_xive_cede_vcpu(struct kvm_vcpu *vcpu);
I can not find this routine. Is it missing or coming later in the patchset ?
C.
>
> static inline int kvmppc_xive_enabled(struct kvm_vcpu *vcpu)
> {
> @@ -714,6 +718,7 @@ static inline int kvmppc_xive_set_irq(struct kvm *kvm, int irq_source_id, u32 ir
> int level, bool line_status) { return -ENODEV; }
> static inline void kvmppc_xive_push_vcpu(struct kvm_vcpu *vcpu) { }
> static inline void kvmppc_xive_pull_vcpu(struct kvm_vcpu *vcpu) { }
> +static inline void kvmppc_xive_cede_vcpu(struct kvm_vcpu *vcpu) { }
>
> static inline int kvmppc_xive_enabled(struct kvm_vcpu *vcpu)
> { return 0; }
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 7e23838b7f9b..d4770b222d7e 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -1144,7 +1144,7 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
> * This has to be done early, not in kvmppc_pseries_do_hcall(), so
> * that the cede logic in kvmppc_run_single_vcpu() works properly.
> */
> -static void kvmppc_nested_cede(struct kvm_vcpu *vcpu)
> +static void kvmppc_cede(struct kvm_vcpu *vcpu)
> {
> vcpu->arch.shregs.msr |= MSR_EE;
> vcpu->arch.ceded = 1;
> @@ -3731,15 +3731,34 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
> /* H_CEDE has to be handled now, not later */
> if (trap = BOOK3S_INTERRUPT_SYSCALL && !vcpu->arch.nested &&
> kvmppc_get_gpr(vcpu, 3) = H_CEDE) {
> - kvmppc_nested_cede(vcpu);
> + kvmppc_cede(vcpu);
> kvmppc_set_gpr(vcpu, 3, 0);
> trap = 0;
> }
> } else {
> kvmppc_xive_push_vcpu(vcpu);
> trap = kvmhv_load_hv_regs_and_go(vcpu, time_limit, lpcr);
> - kvmppc_xive_pull_vcpu(vcpu);
> + /* H_CEDE has to be handled now, not later */
> + /* XICS hcalls must be handled before xive is pulled */
> + if (trap = BOOK3S_INTERRUPT_SYSCALL &&
> + !(vcpu->arch.shregs.msr & MSR_PR)) {
> + unsigned long req = kvmppc_get_gpr(vcpu, 3);
>
> + if (req = H_CEDE) {
> + kvmppc_cede(vcpu);
> + kvmppc_xive_cede_vcpu(vcpu); /* may un-cede */
> + kvmppc_set_gpr(vcpu, 3, 0);
> + trap = 0;
> + }
> + if (req = H_EOI || req = H_CPPR || req = H_IPI ||
> + req = H_IPOLL || req = H_XIRR || req = H_XIRR_X) {
> + unsigned long ret;
> + ret = kvmppc_xive_xics_hcall(vcpu, req);
> + kvmppc_set_gpr(vcpu, 3, ret);
> + trap = 0;
> + }
> + }
> + kvmppc_xive_pull_vcpu(vcpu);
> }
>
> vcpu->arch.slb_max = 0;
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index c11597f815e4..2d0d14ed1d92 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -1397,9 +1397,14 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
> mr r4,r9
> bge fast_guest_return
> 2:
> + /* If we came in through the P9 short path, no real mode hcalls */
> + lwz r0, STACK_SLOT_SHORT_PATH(r1)
> + cmpwi r0, 0
> + bne no_try_real
> /* See if this is an hcall we can handle in real mode */
> cmpwi r12,BOOK3S_INTERRUPT_SYSCALL
> beq hcall_try_real_mode
> +no_try_real:
>
> /* Hypervisor doorbell - exit only if host IPI flag set */
> cmpwi r12, BOOK3S_INTERRUPT_H_DOORBELL
> diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
> index 8632fb998a55..d2266d36a7c7 100644
> --- a/arch/powerpc/kvm/book3s_xive.c
> +++ b/arch/powerpc/kvm/book3s_xive.c
> @@ -2109,6 +2109,31 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
> return 0;
> }
>
> +int kvmppc_xive_xics_hcall(struct kvm_vcpu *vcpu, u32 req)
> +{
> + struct kvmppc_vcore *vc = vcpu->arch.vcore;
> +
> + switch (req) {
> + case H_XIRR:
> + return xive_vm_h_xirr(vcpu);
> + case H_CPPR:
> + return xive_vm_h_cppr(vcpu, kvmppc_get_gpr(vcpu, 4));
> + case H_EOI:
> + return xive_vm_h_eoi(vcpu, kvmppc_get_gpr(vcpu, 4));
> + case H_IPI:
> + return xive_vm_h_ipi(vcpu, kvmppc_get_gpr(vcpu, 4),
> + kvmppc_get_gpr(vcpu, 5));
> + case H_IPOLL:
> + return xive_vm_h_ipoll(vcpu, kvmppc_get_gpr(vcpu, 4));
> + case H_XIRR_X:
> + xive_vm_h_xirr(vcpu);
> + kvmppc_set_gpr(vcpu, 5, get_tb() + vc->tb_offset);
> + return H_SUCCESS;
> + }
> +
> + return H_UNSUPPORTED;
> +}
> +
> int kvmppc_xive_debug_show_queues(struct seq_file *m, struct kvm_vcpu *vcpu)
> {
> struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
>
next prev parent reply other threads:[~2021-02-25 14:51 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-25 13:46 [PATCH v2 00/37] KVM: PPC: Book3S: C-ify the P9 entry/exit code Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 01/37] KVM: PPC: Book3S 64: remove unused kvmppc_h_protect argument Nicholas Piggin
2021-02-26 5:01 ` Daniel Axtens
2021-02-26 23:50 ` Nicholas Piggin
2021-03-05 4:45 ` Daniel Axtens
2021-02-25 13:46 ` [PATCH v2 02/37] KVM: PPC: Book3S HV: Fix CONFIG_SPAPR_TCE_IOMMU=n default hcalls Nicholas Piggin
2021-02-26 5:21 ` Daniel Axtens
2021-02-25 13:46 ` [PATCH v2 03/37] powerpc/64s: Remove KVM handler support from CBE_RAS interrupts Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 04/37] powerpc/64s: remove KVM SKIP test from instruction breakpoint handler Nicholas Piggin
2021-02-26 5:44 ` Daniel Axtens
2021-02-26 23:51 ` Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 05/37] KVM: PPC: Book3S HV: Ensure MSR[ME] is always set in guest MSR Nicholas Piggin
2021-02-26 6:06 ` Daniel Axtens
2021-02-26 23:55 ` Nicholas Piggin
2021-03-05 4:50 ` Daniel Axtens
2021-02-25 13:46 ` [PATCH v2 06/37] KVM: PPC: Book3S 64: move KVM interrupt entry to a common entry point Nicholas Piggin
2021-03-05 5:03 ` Daniel Axtens
2021-02-25 13:46 ` [PATCH v2 07/37] KVM: PPC: Book3S 64: Move GUEST_MODE_SKIP test into KVM Nicholas Piggin
2021-03-05 5:54 ` Daniel Axtens
2021-02-25 13:46 ` [PATCH v2 08/37] KVM: PPC: Book3S 64: add hcall interrupt handler Nicholas Piggin
2021-03-05 6:03 ` Daniel Axtens
2021-02-25 13:46 ` [PATCH v2 09/37] KVM: PPC: Book3S 64: Move hcall early register setup to KVM Nicholas Piggin
2021-03-05 6:48 ` Daniel Axtens
2021-02-25 13:46 ` [PATCH v2 10/37] KVM: PPC: Book3S 64: Move interrupt " Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 11/37] KVM: PPC: Book3S 64: move bad_host_intr check to HV handler Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 12/37] KVM: PPC: Book3S 64: Minimise hcall handler calling convention differences Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 13/37] KVM: PPC: Book3S HV P9: Move radix MMU switching instructions together Nicholas Piggin
2021-02-26 15:56 ` Fabiano Rosas
2021-02-26 23:57 ` Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 14/37] KVM: PPC: Book3S HV P9: implement kvmppc_xive_pull_vcpu in C Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 15/37] KVM: PPC: Book3S HV P9: Move xive vcpu context management into kvmhv_p9_guest_entry Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 16/37] KVM: PPC: Book3S HV P9: Stop handling hcalls in real-mode in the P9 path Nicholas Piggin
2021-02-25 14:51 ` Cédric Le Goater [this message]
2021-02-26 23:59 ` Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 17/37] KVM: PPC: Book3S HV P9: Move setting HDEC after switching to guest LPCR Nicholas Piggin
2021-02-26 16:38 ` Fabiano Rosas
2021-02-26 23:59 ` Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 18/37] KVM: PPC: Book3S HV P9: Use large decrementer for HDEC Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 19/37] KVM: PPC: Book3S HV P9: Use host timer accounting to avoid decrementer read Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 20/37] KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 21/37] powerpc: add set_dec_or_work API for safely updating decrementer Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 22/37] KVM: PPC: Book3S HV P9: Reduce irq_work vs guest decrementer races Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 23/37] KVM: PPC: Book3S HV P9: Implement the rest of the P9 path in C Nicholas Piggin
2021-02-26 22:37 ` Fabiano Rosas
2021-02-27 0:21 ` Nicholas Piggin
2021-02-27 0:55 ` Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 24/37] KVM: PPC: Book3S HV P9: inline kvmhv_load_hv_regs_and_go into __kvmhv_vcpu_entry_p9 Nicholas Piggin
2021-03-02 13:48 ` [PATCH v2 24/37] KVM: PPC: Book3S HV P9: inline kvmhv_load_hv_regs_and_go into __kvmhv_vcpu_entr Fabiano Rosas
2021-02-25 13:46 ` [PATCH v2 25/37] KVM: PPC: Book3S HV P9: Read machine check registers while MSR[RI] is 0 Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 26/37] KVM: PPC: Book3S HV P9: Improve exit timing accounting coverage Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 27/37] KVM: PPC: Book3S HV P9: Move SPR loading after expiry time check Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 28/37] KVM: PPC: Book3S HV P9: Add helpers for OS SPR handling Nicholas Piggin
2021-03-02 15:04 ` Fabiano Rosas
2021-03-04 11:02 ` Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 29/37] KVM: PPC: Book3S HV P9: Switch to guest MMU context as late as possible Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 30/37] KVM: PPC: Book3S HV: Implement radix prefetch workaround by disabling MMU Nicholas Piggin
2021-03-02 21:21 ` Fabiano Rosas
2021-03-04 11:04 ` Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 31/37] KVM: PPC: Book3S HV: Remove support for dependent threads mode on P9 Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 32/37] KVM: PPC: Book3S HV: Remove radix guest support from P7/8 path Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 33/37] KVM: PPC: Book3S HV: small pseries_do_hcall cleanup Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 34/37] KVM: PPC: Book3S HV: add virtual mode handlers for HPT hcalls and page faults Nicholas Piggin
2021-03-03 20:09 ` Fabiano Rosas
2021-03-04 11:05 ` Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 35/37] KVM: PPC: Book3S HV P9: implement hash guest support Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 36/37] KVM: PPC: Book3S HV P9: implement hash host / " Nicholas Piggin
2021-02-25 13:46 ` [PATCH v2 37/37] KVM: PPC: Book3S HV: remove POWER9 support from P7/8 paths Nicholas Piggin
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