[PATCH 26/60] 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.

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>
---
RFC V2: add ASSERT(), modify error message (Andrew Cooper)
V1: constify pointers, avoid cpumask on stack (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 d9836779d1..86a6e4bf7b 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)
@@ -1923,7 +1923,7 @@ 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;
 
@@ -1986,12 +1986,11 @@ 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;
         }
 
@@ -2026,7 +2025,7 @@ 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 9b063639c9..9c23cf6aab 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 903611fb0d..215c2e7d84 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 c200e9024f..2d3427eb0f 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -128,8 +128,7 @@ 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;
 
@@ -161,7 +160,7 @@ 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 bc986d131d..e48f17cb19 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -540,8 +540,7 @@ 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() */
@@ -552,18 +551,13 @@ 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 53a3e55f0b..2c1ba32d83 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -314,14 +314,52 @@ 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. */
@@ -1673,7 +1711,7 @@ 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
     {
         struct vcpu *idle = idle_vcpu[cpu];
@@ -1894,7 +1932,7 @@ 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;
     get_sched_res(0)->sched_priv = sched_alloc_pdata(&ops, 0);
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 d1bfc82f57..a6e929685c 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 ca70ffb7e9..2a8789b438 100644
--- a/xen/include/xen/sched-if.h
+++ b/xen/include/xen/sched-if.h
@@ -452,7 +452,7 @@ 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 13bab258d5..b14dff6fc4 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -660,7 +660,7 @@ 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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