M: Juergen Gross <jgross@suse.com>
M: Dario Faggioli <dfaggioli@suse.com>
S: Supported
-F: xen/common/sched/cpupool.c
+F: xen/common/sched/*cpupool.c
DEVICE TREE
M: Stefano Stabellini <sstabellini@kernel.org>
--- /dev/null
+Boot time cpupools
+==================
+
+When BOOT_TIME_CPUPOOLS is enabled in the Xen configuration, it is possible to
+create cpupools during boot phase by specifying them in the device tree.
+ACPI is not supported for this feature.
+
+Cpupools specification nodes shall be direct childs of /chosen node.
+Each cpupool node contains the following properties:
+
+- compatible (mandatory)
+
+ Must always include the compatiblity string: "xen,cpupool".
+
+- cpupool-cpus (mandatory)
+
+ Must be a list of device tree phandle to nodes describing cpus (e.g. having
+ device_type = "cpu"), it can't be empty.
+
+- cpupool-sched (optional)
+
+ Must be a string having the name of a Xen scheduler. Check the sched=<...>
+ boot argument for allowed values [1]. When this property is omitted, the Xen
+ default scheduler will be used.
+
+
+Constraints
+===========
+
+If no cpupools are specified, all cpus will be assigned to one cpupool
+implicitly created (Pool-0).
+
+If cpupools node are specified, but not every cpu brought up by Xen is assigned,
+all the not assigned cpu will be assigned to an additional cpupool.
+
+If a cpu is assigned to a cpupool, but it's not brought up correctly, Xen will
+stop.
+
+The boot cpu must be assigned to Pool-0, so the cpupool containing that core
+will become Pool-0 automatically.
+
+
+Examples
+========
+
+A system having two types of core, the following device tree specification will
+instruct Xen to have two cpupools:
+
+- The cpupool described by node cpupool_a will have 4 cpus assigned.
+- The cpupool described by node cpupool_b will have 2 cpus assigned.
+
+The following example can work only if hmp-unsafe=1 is passed to Xen boot
+arguments, otherwise not all cores will be brought up by Xen and the cpupool
+creation process will stop Xen.
+
+
+a72_1: cpu@0 {
+ compatible = "arm,cortex-a72";
+ reg = <0x0 0x0>;
+ device_type = "cpu";
+ [...]
+};
+
+a72_2: cpu@1 {
+ compatible = "arm,cortex-a72";
+ reg = <0x0 0x1>;
+ device_type = "cpu";
+ [...]
+};
+
+a53_1: cpu@100 {
+ compatible = "arm,cortex-a53";
+ reg = <0x0 0x100>;
+ device_type = "cpu";
+ [...]
+};
+
+a53_2: cpu@101 {
+ compatible = "arm,cortex-a53";
+ reg = <0x0 0x101>;
+ device_type = "cpu";
+ [...]
+};
+
+a53_3: cpu@102 {
+ compatible = "arm,cortex-a53";
+ reg = <0x0 0x102>;
+ device_type = "cpu";
+ [...]
+};
+
+a53_4: cpu@103 {
+ compatible = "arm,cortex-a53";
+ reg = <0x0 0x103>;
+ device_type = "cpu";
+ [...]
+};
+
+chosen {
+
+ cpupool_a {
+ compatible = "xen,cpupool";
+ cpupool-cpus = <&a53_1 &a53_2 &a53_3 &a53_4>;
+ };
+ cpupool_b {
+ compatible = "xen,cpupool";
+ cpupool-cpus = <&a72_1 &a72_2>;
+ cpupool-sched = "credit2";
+ };
+
+ [...]
+
+};
+
+
+A system having the cpupools specification below will instruct Xen to have three
+cpupools:
+
+- The cpupool described by node cpupool_a will have 2 cpus assigned.
+- The cpupool described by node cpupool_b will have 2 cpus assigned.
+- An additional cpupool will be created, having 2 cpus assigned (created by Xen
+ with all the unassigned cpus a53_3 and a53_4).
+
+chosen {
+
+ cpupool_a {
+ compatible = "xen,cpupool";
+ cpupool-cpus = <&a53_1 &a53_2>;
+ };
+ cpupool_b {
+ compatible = "xen,cpupool";
+ cpupool-cpus = <&a72_1 &a72_2>;
+ cpupool-sched = "null";
+ };
+
+ [...]
+
+};
+
+[1] docs/misc/xen-command-line.pandoc
unsigned int __init dom0_max_vcpus(void)
{
if ( opt_dom0_max_vcpus == 0 )
- opt_dom0_max_vcpus = num_online_cpus();
+ {
+ ASSERT(cpupool0);
+ opt_dom0_max_vcpus = cpumask_weight(cpupool_valid_cpus(cpupool0));
+ }
if ( opt_dom0_max_vcpus > MAX_VIRT_CPUS )
opt_dom0_max_vcpus = MAX_VIRT_CPUS;
extern void smp_init_cpus(void);
extern void smp_clear_cpu_maps (void);
extern int smp_get_max_cpus (void);
+
+#define cpu_physical_id(cpu) cpu_logical_map(cpu)
+
#endif
/*
default "credit2"
endmenu
+
+config BOOT_TIME_CPUPOOLS
+ bool "Create cpupools at boot time"
+ depends on HAS_DEVICE_TREE
+ help
+ Creates cpupools during boot time and assigns cpus to them. Cpupools
+ options can be specified in the device tree.
+obj-$(CONFIG_BOOT_TIME_CPUPOOLS) += boot-cpupool.init.o
obj-y += cpupool.o
obj-$(CONFIG_SCHED_ARINC653) += arinc653.o
obj-$(CONFIG_SCHED_CREDIT) += credit.o
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * xen/common/boot_cpupools.c
+ *
+ * Code to create cpupools at boot time.
+ *
+ * Copyright (C) 2022 Arm Ltd.
+ */
+
+#include <xen/sched.h>
+#include <asm/acpi.h>
+
+/*
+ * pool_cpu_map: Index is logical cpu number, content is cpupool id, (-1) for
+ * unassigned.
+ * pool_sched_map: Index is cpupool id, content is scheduler id, (-1) for
+ * unassigned.
+ */
+static int __initdata pool_cpu_map[NR_CPUS] = { [0 ... NR_CPUS-1] = -1 };
+static int __initdata pool_sched_map[NR_CPUS] = { [0 ... NR_CPUS-1] = -1 };
+static unsigned int __initdata next_pool_id;
+
+#define BTCPUPOOLS_DT_NODE_NO_REG (-1)
+#define BTCPUPOOLS_DT_NODE_NO_LOG_CPU (-2)
+
+static int __init get_logical_cpu_from_hw_id(unsigned int hwid)
+{
+ unsigned int i;
+
+ for ( i = 0; i < nr_cpu_ids; i++ )
+ {
+ if ( cpu_physical_id(i) == hwid )
+ return i;
+ }
+
+ return -1;
+}
+
+static int __init
+get_logical_cpu_from_cpu_node(const struct dt_device_node *cpu_node)
+{
+ int cpu_num;
+ const __be32 *prop;
+ unsigned int cpu_reg;
+
+ prop = dt_get_property(cpu_node, "reg", NULL);
+ if ( !prop )
+ return BTCPUPOOLS_DT_NODE_NO_REG;
+
+ cpu_reg = dt_read_number(prop, dt_n_addr_cells(cpu_node));
+
+ cpu_num = get_logical_cpu_from_hw_id(cpu_reg);
+ if ( cpu_num < 0 )
+ return BTCPUPOOLS_DT_NODE_NO_LOG_CPU;
+
+ return cpu_num;
+}
+
+static int __init check_and_get_sched_id(const char* scheduler_name)
+{
+ int sched_id = sched_get_id_by_name(scheduler_name);
+
+ if ( sched_id < 0 )
+ panic("Scheduler %s does not exists!\n", scheduler_name);
+
+ return sched_id;
+}
+
+void __init btcpupools_dtb_parse(void)
+{
+ const struct dt_device_node *chosen, *node;
+
+ if ( !acpi_disabled )
+ return;
+
+ chosen = dt_find_node_by_path("/chosen");
+ if ( !chosen )
+ panic("/chosen missing. Boot time cpupools can't be parsed from DT.\n");
+
+ dt_for_each_child_node(chosen, node)
+ {
+ const struct dt_device_node *phandle_node;
+ int sched_id = -1;
+ const char* scheduler_name;
+ unsigned int i = 0;
+
+ if ( !dt_device_is_compatible(node, "xen,cpupool") )
+ continue;
+
+ if ( !dt_property_read_string(node, "cpupool-sched", &scheduler_name) )
+ sched_id = check_and_get_sched_id(scheduler_name);
+
+ phandle_node = dt_parse_phandle(node, "cpupool-cpus", i++);
+ if ( !phandle_node )
+ panic("Missing or empty cpupool-cpus property!\n");
+
+ while ( phandle_node )
+ {
+ int cpu_num;
+
+ cpu_num = get_logical_cpu_from_cpu_node(phandle_node);
+
+ if ( cpu_num < 0 )
+ panic("Error retrieving logical cpu from node %s (%d)\n",
+ dt_node_name(node), cpu_num);
+
+ if ( pool_cpu_map[cpu_num] != -1 )
+ panic("Logical cpu %d already added to a cpupool!\n", cpu_num);
+
+ pool_cpu_map[cpu_num] = next_pool_id;
+
+ phandle_node = dt_parse_phandle(node, "cpupool-cpus", i++);
+ }
+
+ /* Save scheduler choice for this cpupool id */
+ pool_sched_map[next_pool_id] = sched_id;
+
+ /* Let Xen generate pool ids */
+ next_pool_id++;
+ }
+}
+
+void __init btcpupools_allocate_pools(void)
+{
+ unsigned int i;
+ bool add_extra_cpupool = false;
+ int swap_id = -1;
+
+ /*
+ * If there are no cpupools, the value of next_pool_id is zero, so the code
+ * below will assign every cpu to cpupool0 as the default behavior.
+ * When there are cpupools, the code below is assigning all the not
+ * assigned cpu to a new pool (next_pool_id value is the last id + 1).
+ * In the same loop we check if there is any assigned cpu that is not
+ * online.
+ */
+ for ( i = 0; i < nr_cpu_ids; i++ )
+ {
+ if ( cpumask_test_cpu(i, &cpu_online_map) )
+ {
+ /* Unassigned cpu gets next_pool_id pool id value */
+ if ( pool_cpu_map[i] < 0 )
+ {
+ pool_cpu_map[i] = next_pool_id;
+ add_extra_cpupool = true;
+ }
+
+ /*
+ * Cpu0 must be in cpupool0, otherwise some operations like moving
+ * cpus between cpupools, cpu hotplug, destroying cpupools, shutdown
+ * of the host, might not work in a sane way.
+ */
+ if ( !i && (pool_cpu_map[0] != 0) )
+ swap_id = pool_cpu_map[0];
+
+ if ( swap_id != -1 )
+ {
+ if ( pool_cpu_map[i] == swap_id )
+ pool_cpu_map[i] = 0;
+ else if ( pool_cpu_map[i] == 0 )
+ pool_cpu_map[i] = swap_id;
+ }
+ }
+ else
+ {
+ if ( pool_cpu_map[i] >= 0 )
+ panic("Pool-%d contains cpu%u that is not online!\n",
+ pool_cpu_map[i], i);
+ }
+ }
+
+ /* A swap happened, swap schedulers between cpupool id 0 and the other */
+ if ( swap_id != -1 )
+ {
+ int swap_sched = pool_sched_map[swap_id];
+
+ pool_sched_map[swap_id] = pool_sched_map[0];
+ pool_sched_map[0] = swap_sched;
+ }
+
+ if ( add_extra_cpupool )
+ next_pool_id++;
+
+ /* Create cpupools with selected schedulers */
+ for ( i = 0; i < next_pool_id; i++ )
+ cpupool_create_pool(i, pool_sched_map[i]);
+}
+
+unsigned int __init btcpupools_get_cpupool_id(unsigned int cpu)
+{
+ ASSERT((cpu < NR_CPUS) && (pool_cpu_map[cpu] >= 0));
+
+ printk(XENLOG_INFO "Logical CPU %u in Pool-%d (Scheduler id: %d).\n",
+ cpu, pool_cpu_map[cpu], pool_sched_map[pool_cpu_map[cpu]]);
+
+ return pool_cpu_map[cpu];
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
cpupool_put(cpupool0);
register_cpu_notifier(&cpu_nfb);
+ btcpupools_dtb_parse();
+
+ btcpupools_allocate_pools();
+
spin_lock(&cpupool_lock);
cpumask_copy(&cpupool_free_cpus, &cpu_online_map);
for_each_cpu ( cpu, &cpupool_free_cpus )
- cpupool_assign_cpu_locked(cpupool0, cpu);
+ {
+ unsigned int pool_id = btcpupools_get_cpupool_id(cpu);
+ struct cpupool *pool = cpupool_find_by_id(pool_id);
+
+ ASSERT(pool);
+ cpupool_assign_cpu_locked(pool, cpu);
+ }
spin_unlock(&cpupool_lock);
void arch_do_physinfo(struct xen_sysctl_physinfo *pi);
+#ifdef CONFIG_BOOT_TIME_CPUPOOLS
+void btcpupools_allocate_pools(void);
+unsigned int btcpupools_get_cpupool_id(unsigned int cpu);
+void btcpupools_dtb_parse(void);
+
+#else /* !CONFIG_BOOT_TIME_CPUPOOLS */
+static inline void btcpupools_allocate_pools(void) {}
+static inline void btcpupools_dtb_parse(void) {}
+static inline unsigned int btcpupools_get_cpupool_id(unsigned int cpu)
+{
+ return 0;
+}
+#endif
+
#endif /* __SCHED_H__ */
/*
projects / xen.git / commitdiff