Commit 520fe9c6 authored by Suresh E. Warrier's avatar Suresh E. Warrier Committed by Paul Mackerras
Browse files

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: default avatarSuresh Warrier <warrier@linux.vnet.ibm.com>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent e17769eb

arch/powerpc/include/asm/kvm_ppc.h

+1 −0
Original line number Diff line number Diff line
@@ -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) {};

arch/powerpc/kvm/book3s_hv.c

+11 −0
Original line number Diff line number Diff line
@@ -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);

arch/powerpc/kvm/book3s_hv_rm_xics.c

+4 −1
Original line number Diff line number Diff line
@@ -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);

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