summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/kvm
diff options
context:
space:
mode:
authorSuresh E. Warrier <warrier@linux.vnet.ibm.com>2015-12-21 23:33:57 +0100
committerPaul Mackerras <paulus@samba.org>2016-02-29 06:25:06 +0100
commit520fe9c607d3acea96391aad27e17518bd7d39bd (patch)
treeee3c420760c8d739bfe2cfa9d928c40622545c69 /arch/powerpc/kvm
parentKVM: PPC: Book3S HV: Send IPI to host core to wake VCPU (diff)
downloadlinux-520fe9c607d3acea96391aad27e17518bd7d39bd.tar.xz
linux-520fe9c607d3acea96391aad27e17518bd7d39bd.zip
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 <warrier@linux.vnet.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/kvm')
-rw-r--r--arch/powerpc/kvm/book3s_hv.c11
-rw-r--r--arch/powerpc/kvm/book3s_hv_rm_xics.c5
2 files changed, 15 insertions, 1 deletions
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);