From 3102f7843c75014fa15d3e6fda3b49f61bc467b4 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Fri, 23 May 2014 18:15:29 +1000 Subject: [PATCH] powerpc/kvm/book3s_hv: Use threads_per_subcore in KVM To support split core on POWER8 we need to modify various parts of the KVM code to use threads_per_subcore instead of threads_per_core. On systems that do not support split core threads_per_subcore == threads_per_core and these changes are a nop. We use threads_per_subcore as the value reported by KVM_CAP_PPC_SMT. This communicates to userspace that guests can only be created with a value of threads_per_core that is less than or equal to the current threads_per_subcore. This ensures that guests can only be created with a thread configuration that we are able to run given the current split core mode. Although threads_per_subcore can change during the life of the system, the commit that enables that will ensure that threads_per_subcore does not change during the life of a KVM VM. Signed-off-by: Michael Ellerman Signed-off-by: Michael Neuling Acked-by: Alexander Graf Acked-by: Paul Mackerras Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kvm/book3s_hv.c | 26 ++++++++++++++++---------- arch/powerpc/kvm/powerpc.c | 2 +- 2 files changed, 17 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index d7b74f888ad8..5e86f28c9d2f 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1266,7 +1266,7 @@ static struct kvm_vcpu *kvmppc_core_vcpu_create_hv(struct kvm *kvm, int core; struct kvmppc_vcore *vcore; - core = id / threads_per_core; + core = id / threads_per_subcore; if (core >= KVM_MAX_VCORES) goto out; @@ -1305,7 +1305,7 @@ static struct kvm_vcpu *kvmppc_core_vcpu_create_hv(struct kvm *kvm, init_waitqueue_head(&vcore->wq); vcore->preempt_tb = TB_NIL; vcore->lpcr = kvm->arch.lpcr; - vcore->first_vcpuid = core * threads_per_core; + vcore->first_vcpuid = core * threads_per_subcore; vcore->kvm = kvm; } kvm->arch.vcores[core] = vcore; @@ -1495,16 +1495,19 @@ static void kvmppc_wait_for_nap(struct kvmppc_vcore *vc) static int on_primary_thread(void) { int cpu = smp_processor_id(); - int thr = cpu_thread_in_core(cpu); + int thr; - if (thr) + /* Are we on a primary subcore? */ + if (cpu_thread_in_subcore(cpu)) return 0; - while (++thr < threads_per_core) + + thr = 0; + while (++thr < threads_per_subcore) if (cpu_online(cpu + thr)) return 0; /* Grab all hw threads so they can't go into the kernel */ - for (thr = 1; thr < threads_per_core; ++thr) { + for (thr = 1; thr < threads_per_subcore; ++thr) { if (kvmppc_grab_hwthread(cpu + thr)) { /* Couldn't grab one; let the others go */ do { @@ -1563,15 +1566,18 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc) } /* - * Make sure we are running on thread 0, and that - * secondary threads are offline. + * Make sure we are running on primary threads, and that secondary + * threads are offline. Also check if the number of threads in this + * guest are greater than the current system threads per guest. */ - if (threads_per_core > 1 && !on_primary_thread()) { + if ((threads_per_core > 1) && + ((vc->num_threads > threads_per_subcore) || !on_primary_thread())) { list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) vcpu->arch.ret = -EBUSY; goto out; } + vc->pcpu = smp_processor_id(); list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) { kvmppc_start_thread(vcpu); @@ -1599,7 +1605,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc) /* wait for secondary threads to finish writing their state to memory */ if (vc->nap_count < vc->n_woken) kvmppc_wait_for_nap(vc); - for (i = 0; i < threads_per_core; ++i) + for (i = 0; i < threads_per_subcore; ++i) kvmppc_release_hwthread(vc->pcpu + i); /* prevent other vcpu threads from doing kvmppc_start_thread() now */ vc->vcore_state = VCORE_EXITING; diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c index 3cf541a53e2a..27919a8715cf 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -384,7 +384,7 @@ int kvm_dev_ioctl_check_extension(long ext) #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE case KVM_CAP_PPC_SMT: if (hv_enabled) - r = threads_per_core; + r = threads_per_subcore; else r = 0; break;