From 529a76fba40e34037e9473d9f461c39604eb34f9 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Wed, 23 Oct 2019 16:53:52 +0100 Subject: [PATCH] xen/pvhsim: fix cpu onlining MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Since commit 8d3c326f6756d1 ("xen: let vcpu_create() select processor") the initial processor for all pv-shim vcpus will be 0, as no other cpus are online when the vcpus are created. Before that commit the vcpus would have processors set not being online yet, which worked just by chance. When the pv-shim vcpu becomes active it will have a hard affinity not matching its initial processor assignment leading to failing ASSERT()s or other problems depending on the selected scheduler. Fix that by doing the affinity setting after onlining the cpu but before taking the vcpu up. For vcpu 0 this is still in sched_setup_dom0_vcpus(), for the other vcpus setting the affinity there can be dropped. Fixes: 8d3c326f6756d1 ("xen: let vcpu_create() select processor") Reported-by: Sergey Dyasli Tested-by: Sergey Dyasli Reviewed-by: Roger Pau Monné Acked-by: Jan Beulich Release-acked-by: Juergen Gross Signed-off-by: Juergen Gross Acked-by: George Dunlap --- xen/arch/x86/pv/shim.c | 2 ++ xen/common/schedule.c | 16 ++++++++++------ 2 files changed, 12 insertions(+), 6 deletions(-) diff --git a/xen/arch/x86/pv/shim.c b/xen/arch/x86/pv/shim.c index 5edbcd9ac5..4329eaaefe 100644 --- a/xen/arch/x86/pv/shim.c +++ b/xen/arch/x86/pv/shim.c @@ -837,6 +837,8 @@ long pv_shim_cpu_up(void *data) v->vcpu_id, rc); return rc; } + + vcpu_set_hard_affinity(v, cpumask_of(v->vcpu_id)); } wake = test_and_clear_bit(_VPF_down, &v->pause_flags); diff --git a/xen/common/schedule.c b/xen/common/schedule.c index c327c40b92..e70cc70a65 100644 --- a/xen/common/schedule.c +++ b/xen/common/schedule.c @@ -3102,13 +3102,17 @@ void __init sched_setup_dom0_vcpus(struct domain *d) for ( i = 1; i < d->max_vcpus; i++ ) vcpu_create(d, i); - for_each_sched_unit ( d, unit ) + /* + * PV-shim: vcpus are pinned 1:1. + * Initially only 1 cpu is online, others will be dealt with when + * onlining them. This avoids pinning a vcpu to a not yet online cpu here. + */ + if ( pv_shim ) + sched_set_affinity(d->vcpu[0]->sched_unit, + cpumask_of(0), cpumask_of(0)); + else { - unsigned int id = unit->unit_id; - - if ( pv_shim ) - sched_set_affinity(unit, cpumask_of(id), cpumask_of(id)); - else + for_each_sched_unit ( d, unit ) { if ( !opt_dom0_vcpus_pin && !dom0_affinity_relaxed ) sched_set_affinity(unit, &dom0_cpus, NULL); -- 2.39.5