[Xen-devel] [PATCH v3 20/47] xen: let vcpu_create() select processor

[Juergen Gross <jgross@suse.com>]

Today there are two distinct scenarios for vcpu_create(): either for
creation of idle-domain vcpus (vcpuid == processor) or for creation of
"normal" domain vcpus (including dom0), where the caller selects the
initial processor on a round-robin scheme of the allowed processors
(allowed being based on cpupool and affinities).

Instead of passing the initial processor to vcpu_create() and passing
on to sched_init_vcpu() let sched_init_vcpu() do the processor
selection. For supporting dom0 vcpu creation use the node_affinity of
the domain as a base for selecting the processors. User domains will
have initially all nodes set, so this is no different behavior compared
to today. In theory this is not guaranteed as vcpus are created only
with XEN_DOMCTL_max_vcpus being called, but this call is going to be
removed in future and the toolstack doesn't call
XEN_DOMCTL_setnodeaffinity before calling XEN_DOMCTL_max_vcpus.

To be able to use const struct domain * make cpupool_domain_cpumask()
take a const domain pointer, too.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Julien Grall <julien.grall@arm.com>
---
RFC V2:
- add ASSERT(), modify error message (Andrew Cooper)
V1:
- constify pointers, avoid cpumask on stack (Jan Beulich)
V3:
- style correction (Jan Beulich)
---
 xen/arch/arm/domain_build.c      | 13 ++++++------
 xen/arch/x86/dom0_build.c        | 10 +++------
 xen/arch/x86/hvm/dom0_build.c    |  9 ++------
 xen/arch/x86/pv/dom0_build.c     | 10 ++-------
 xen/common/domain.c              |  5 ++---
 xen/common/domctl.c              | 10 ++-------
 xen/common/schedule.c            | 44 +++++++++++++++++++++++++++++++++++++---
 xen/include/asm-x86/dom0_build.h |  3 +--
 xen/include/xen/domain.h         |  3 +--
 xen/include/xen/sched-if.h       |  2 +-
 xen/include/xen/sched.h          |  2 +-
 11 files changed, 62 insertions(+), 49 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index a0fee1ef13..f6575f918d 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -80,7 +80,7 @@ unsigned int __init dom0_max_vcpus(void)
 
 struct vcpu *__init alloc_dom0_vcpu0(struct domain *dom0)
 {
-    return vcpu_create(dom0, 0, 0);
+    return vcpu_create(dom0, 0);
 }
 
 static unsigned int __init get_allocation_size(paddr_t size)
@@ -1925,7 +1925,7 @@ static void __init find_gnttab_region(struct domain *d,
 
 static int __init construct_domain(struct domain *d, struct kernel_info *kinfo)
 {
-    int i, cpu;
+    int i;
     struct vcpu *v = d->vcpu[0];
     struct cpu_user_regs *regs = &v->arch.cpu_info->guest_cpu_user_regs;
 
@@ -1988,12 +1988,11 @@ static int __init construct_domain(struct domain *d, struct kernel_info *kinfo)
     }
 #endif
 
-    for ( i = 1, cpu = 0; i < d->max_vcpus; i++ )
+    for ( i = 1; i < d->max_vcpus; i++ )
     {
-        cpu = cpumask_cycle(cpu, &cpu_online_map);
-        if ( vcpu_create(d, i, cpu) == NULL )
+        if ( vcpu_create(d, i) == NULL )
         {
-            printk("Failed to allocate dom0 vcpu %d on pcpu %d\n", i, cpu);
+            printk("Failed to allocate d0v%u\n", i);
             break;
         }
 
@@ -2028,7 +2027,7 @@ static int __init construct_domU(struct domain *d,
 
     kinfo.vpl011 = dt_property_read_bool(node, "vpl011");
 
-    if ( vcpu_create(d, 0, 0) == NULL )
+    if ( vcpu_create(d, 0) == NULL )
         return -ENOMEM;
     d->max_pages = ~0U;
 
diff --git a/xen/arch/x86/dom0_build.c b/xen/arch/x86/dom0_build.c
index c69570920c..6265dd4a1c 100644
--- a/xen/arch/x86/dom0_build.c
+++ b/xen/arch/x86/dom0_build.c
@@ -198,12 +198,9 @@ custom_param("dom0_nodes", parse_dom0_nodes);
 
 static cpumask_t __initdata dom0_cpus;
 
-struct vcpu *__init dom0_setup_vcpu(struct domain *d,
-                                    unsigned int vcpu_id,
-                                    unsigned int prev_cpu)
+struct vcpu *__init dom0_setup_vcpu(struct domain *d, unsigned int vcpu_id)
 {
-    unsigned int cpu = cpumask_cycle(prev_cpu, &dom0_cpus);
-    struct vcpu *v = vcpu_create(d, vcpu_id, cpu);
+    struct vcpu *v = vcpu_create(d, vcpu_id);
 
     if ( v )
     {
@@ -273,8 +270,7 @@ struct vcpu *__init alloc_dom0_vcpu0(struct domain *dom0)
     dom0->node_affinity = dom0_nodes;
     dom0->auto_node_affinity = !dom0_nr_pxms;
 
-    return dom0_setup_vcpu(dom0, 0,
-                           cpumask_last(&dom0_cpus) /* so it wraps around to first pcpu */);
+    return dom0_setup_vcpu(dom0, 0);
 }
 
 #ifdef CONFIG_SHADOW_PAGING
diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
index 8845399ae9..fd8d9609b1 100644
--- a/xen/arch/x86/hvm/dom0_build.c
+++ b/xen/arch/x86/hvm/dom0_build.c
@@ -614,7 +614,7 @@ static int __init pvh_setup_cpus(struct domain *d, paddr_t entry,
                                  paddr_t start_info)
 {
     struct vcpu *v = d->vcpu[0];
-    unsigned int cpu = v->processor, i;
+    unsigned int i;
     int rc;
     /*
      * This sets the vCPU state according to the state described in
@@ -636,12 +636,7 @@ static int __init pvh_setup_cpus(struct domain *d, paddr_t entry,
     };
 
     for ( i = 1; i < d->max_vcpus; i++ )
-    {
-        const struct vcpu *p = dom0_setup_vcpu(d, i, cpu);
-
-        if ( p )
-            cpu = p->processor;
-    }
+        dom0_setup_vcpu(d, i);
 
     domain_update_node_affinity(d);
 
diff --git a/xen/arch/x86/pv/dom0_build.c b/xen/arch/x86/pv/dom0_build.c
index 1bd53e9c08..565c6c8b44 100644
--- a/xen/arch/x86/pv/dom0_build.c
+++ b/xen/arch/x86/pv/dom0_build.c
@@ -285,7 +285,7 @@ int __init dom0_construct_pv(struct domain *d,
                              module_t *initrd,
                              char *cmdline)
 {
-    int i, cpu, rc, compatible, order, machine;
+    int i, rc, compatible, order, machine;
     struct cpu_user_regs *regs;
     unsigned long pfn, mfn;
     unsigned long nr_pages;
@@ -694,14 +694,8 @@ int __init dom0_construct_pv(struct domain *d,
 
     printk("Dom%u has maximum %u VCPUs\n", d->domain_id, d->max_vcpus);
 
-    cpu = v->processor;
     for ( i = 1; i < d->max_vcpus; i++ )
-    {
-        const struct vcpu *p = dom0_setup_vcpu(d, i, cpu);
-
-        if ( p )
-            cpu = p->processor;
-    }
+        dom0_setup_vcpu(d, i);
 
     domain_update_node_affinity(d);
     d->arch.paging.mode = 0;
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 8c782ee03f..a3e23f2ee7 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -135,8 +135,7 @@ static void vcpu_destroy(struct vcpu *v)
     free_vcpu_struct(v);
 }
 
-struct vcpu *vcpu_create(
-    struct domain *d, unsigned int vcpu_id, unsigned int cpu_id)
+struct vcpu *vcpu_create(struct domain *d, unsigned int vcpu_id)
 {
     struct vcpu *v;
 
@@ -168,7 +167,7 @@ struct vcpu *vcpu_create(
         init_waitqueue_vcpu(v);
     }
 
-    if ( sched_init_vcpu(v, cpu_id) != 0 )
+    if ( sched_init_vcpu(v) != 0 )
         goto fail_wq;
 
     if ( arch_vcpu_create(v) != 0 )
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index 2f9768f08f..8a694e0d37 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -532,8 +532,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
 
     case XEN_DOMCTL_max_vcpus:
     {
-        unsigned int i, max = op->u.max_vcpus.max, cpu;
-        cpumask_t *online;
+        unsigned int i, max = op->u.max_vcpus.max;
 
         ret = -EINVAL;
         if ( (d == current->domain) || /* no domain_pause() */
@@ -544,18 +543,13 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
         domain_pause(d);
 
         ret = -ENOMEM;
-        online = cpupool_domain_cpumask(d);
 
         for ( i = 0; i < max; i++ )
         {
             if ( d->vcpu[i] != NULL )
                 continue;
 
-            cpu = (i == 0) ?
-                cpumask_any(online) :
-                cpumask_cycle(d->vcpu[i-1]->processor, online);
-
-            if ( vcpu_create(d, i, cpu) == NULL )
+            if ( vcpu_create(d, i) == NULL )
                 goto maxvcpu_out;
         }
 
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 05bc42d7e9..74769f2f9b 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -371,14 +371,52 @@ static struct sched_unit *sched_alloc_unit(struct vcpu *v)
     return NULL;
 }
 
-int sched_init_vcpu(struct vcpu *v, unsigned int processor)
+static unsigned int sched_select_initial_cpu(const struct vcpu *v)
+{
+    const struct domain *d = v->domain;
+    nodeid_t node;
+    spinlock_t *lock;
+    unsigned long flags;
+    unsigned int cpu_ret, cpu = smp_processor_id();
+    cpumask_t *cpus = cpumask_scratch_cpu(cpu);
+
+    lock = pcpu_schedule_lock_irqsave(cpu, &flags);
+    cpumask_clear(cpus);
+    for_each_node_mask ( node, d->node_affinity )
+        cpumask_or(cpus, cpus, &node_to_cpumask(node));
+    cpumask_and(cpus, cpus, cpupool_domain_cpumask(d));
+    if ( cpumask_empty(cpus) )
+        cpumask_copy(cpus, cpupool_domain_cpumask(d));
+
+    if ( v->vcpu_id == 0 )
+        cpu_ret = cpumask_first(cpus);
+    else
+    {
+        /* We can rely on previous vcpu being available. */
+        ASSERT(!is_idle_domain(d));
+
+        cpu_ret = cpumask_cycle(d->vcpu[v->vcpu_id - 1]->processor, cpus);
+    }
+
+    pcpu_schedule_unlock_irqrestore(lock, flags, cpu);
+
+    return cpu_ret;
+}
+
+int sched_init_vcpu(struct vcpu *v)
 {
     struct domain *d = v->domain;
     struct sched_unit *unit;
+    unsigned int processor;
 
     if ( (unit = sched_alloc_unit(v)) == NULL )
         return 1;
 
+    if ( is_idle_domain(d) )
+        processor = v->vcpu_id;
+    else
+        processor = sched_select_initial_cpu(v);
+
     sched_set_res(unit, get_sched_res(processor));
 
     /* Initialise the per-vcpu timers. */
@@ -1763,7 +1801,7 @@ static int cpu_schedule_up(unsigned int cpu)
         return 0;
 
     if ( idle_vcpu[cpu] == NULL )
-        vcpu_create(idle_vcpu[0]->domain, cpu, cpu);
+        vcpu_create(idle_vcpu[0]->domain, cpu);
     else
         idle_vcpu[cpu]->sched_unit->res = sd;
 
@@ -1942,7 +1980,7 @@ void __init scheduler_init(void)
     BUG_ON(nr_cpu_ids > ARRAY_SIZE(idle_vcpu));
     idle_domain->vcpu = idle_vcpu;
     idle_domain->max_vcpus = nr_cpu_ids;
-    if ( vcpu_create(idle_domain, 0, 0) == NULL )
+    if ( vcpu_create(idle_domain, 0) == NULL )
         BUG();
     get_sched_res(0)->curr = idle_vcpu[0]->sched_unit;
 }
diff --git a/xen/include/asm-x86/dom0_build.h b/xen/include/asm-x86/dom0_build.h
index 33a5483739..3eb4b036e1 100644
--- a/xen/include/asm-x86/dom0_build.h
+++ b/xen/include/asm-x86/dom0_build.h
@@ -11,8 +11,7 @@ extern unsigned int dom0_memflags;
 unsigned long dom0_compute_nr_pages(struct domain *d,
                                     struct elf_dom_parms *parms,
                                     unsigned long initrd_len);
-struct vcpu *dom0_setup_vcpu(struct domain *d, unsigned int vcpu_id,
-                             unsigned int cpu);
+struct vcpu *dom0_setup_vcpu(struct domain *d, unsigned int vcpu_id);
 int dom0_setup_permissions(struct domain *d);
 
 int dom0_construct_pv(struct domain *d, const module_t *image,
diff --git a/xen/include/xen/domain.h b/xen/include/xen/domain.h
index 3f09cb66c0..4ca3db5a18 100644
--- a/xen/include/xen/domain.h
+++ b/xen/include/xen/domain.h
@@ -13,8 +13,7 @@ typedef union {
     struct compat_vcpu_guest_context *cmp;
 } vcpu_guest_context_u __attribute__((__transparent_union__));
 
-struct vcpu *vcpu_create(
-    struct domain *d, unsigned int vcpu_id, unsigned int cpu_id);
+struct vcpu *vcpu_create(struct domain *d, unsigned int vcpu_id);
 
 unsigned int dom0_max_vcpus(void);
 struct vcpu *alloc_dom0_vcpu0(struct domain *dom0);
diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
index b5967d26af..f70182dd4e 100644
--- a/xen/include/xen/sched-if.h
+++ b/xen/include/xen/sched-if.h
@@ -458,7 +458,7 @@ struct cpupool
 #define cpupool_online_cpumask(_pool) \
     (((_pool) == NULL) ? &cpu_online_map : (_pool)->cpu_valid)
 
-static inline cpumask_t* cpupool_domain_cpumask(struct domain *d)
+static inline cpumask_t *cpupool_domain_cpumask(const struct domain *d)
 {
     /*
      * d->cpupool is NULL only for the idle domain, and no one should
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index d4698b3f0d..56ed863b08 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -659,7 +659,7 @@ void __domain_crash(struct domain *d);
 void noreturn asm_domain_crash_synchronous(unsigned long addr);
 
 void scheduler_init(void);
-int  sched_init_vcpu(struct vcpu *v, unsigned int processor);
+int  sched_init_vcpu(struct vcpu *v);
 void sched_destroy_vcpu(struct vcpu *v);
 int  sched_init_domain(struct domain *d, int poolid);
 void sched_destroy_domain(struct domain *d);
-- 
2.16.4


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