From 520fe9c607d3acea96391aad27e17518bd7d39bd Mon Sep 17 00:00:00 2001 From: "Suresh E. Warrier" Date: Mon, 21 Dec 2015 16:33:57 -0600 Subject: [PATCH] KVM: PPC: Book3S HV: Add tunable to control H_IPI redirection Redirecting the wakeup of a VCPU from the H_IPI hypercall to a core running in the host is usually a good idea, most workloads seemed to benefit. However, in one heavily interrupt-driven SMT1 workload, some regression was observed. This patch adds a kvm_hv module parameter called h_ipi_redirect to control this feature. The default value for this tunable is 1 - that is enable the feature. Signed-off-by: Suresh Warrier Signed-off-by: Paul Mackerras --- arch/powerpc/include/asm/kvm_ppc.h | 1 + arch/powerpc/kvm/book3s_hv.c | 11 +++++++++++ arch/powerpc/kvm/book3s_hv_rm_xics.c | 5 ++++- 3 files changed, 16 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h index bc14e9e0e4fe..197a8aca2871 100644 --- a/arch/powerpc/include/asm/kvm_ppc.h +++ b/arch/powerpc/include/asm/kvm_ppc.h @@ -464,6 +464,7 @@ extern int kvmppc_xics_set_icp(struct kvm_vcpu *vcpu, u64 icpval); extern int kvmppc_xics_connect_vcpu(struct kvm_device *dev, struct kvm_vcpu *vcpu, u32 cpu); extern void kvmppc_xics_ipi_action(void); +extern int h_ipi_redirect; #else static inline void kvmppc_alloc_host_rm_ops(void) {}; static inline void kvmppc_free_host_rm_ops(void) {}; diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index c3c731085c1f..f47fffefadc1 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -81,6 +81,17 @@ static int target_smt_mode; module_param(target_smt_mode, int, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(target_smt_mode, "Target threads per core (0 = max)"); +#ifdef CONFIG_KVM_XICS +static struct kernel_param_ops module_param_ops = { + .set = param_set_int, + .get = param_get_int, +}; + +module_param_cb(h_ipi_redirect, &module_param_ops, &h_ipi_redirect, + S_IRUGO | S_IWUSR); +MODULE_PARM_DESC(h_ipi_redirect, "Redirect H_IPI wakeup to a free host core"); +#endif + static void kvmppc_end_cede(struct kvm_vcpu *vcpu); static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu); diff --git a/arch/powerpc/kvm/book3s_hv_rm_xics.c b/arch/powerpc/kvm/book3s_hv_rm_xics.c index e673fb9fee98..980d8a6f7284 100644 --- a/arch/powerpc/kvm/book3s_hv_rm_xics.c +++ b/arch/powerpc/kvm/book3s_hv_rm_xics.c @@ -24,6 +24,9 @@ #define DEBUG_PASSUP +int h_ipi_redirect = 1; +EXPORT_SYMBOL(h_ipi_redirect); + static void icp_rm_deliver_irq(struct kvmppc_xics *xics, struct kvmppc_icp *icp, u32 new_irq); @@ -148,7 +151,7 @@ static void icp_rm_set_vcpu_irq(struct kvm_vcpu *vcpu, cpu = vcpu->arch.thread_cpu; if (cpu < 0 || cpu >= nr_cpu_ids) { hcore = -1; - if (kvmppc_host_rm_ops_hv) + if (kvmppc_host_rm_ops_hv && h_ipi_redirect) hcore = find_available_hostcore(XICS_RM_KICK_VCPU); if (hcore != -1) { icp_send_hcore_msg(hcore, vcpu);