diff options
Diffstat (limited to 'arch/powerpc/platforms/pseries/smp.c')
-rw-r--r-- | arch/powerpc/platforms/pseries/smp.c | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/smp.c b/arch/powerpc/platforms/pseries/smp.c new file mode 100644 index 0000000000..c597711ef2 --- /dev/null +++ b/arch/powerpc/platforms/pseries/smp.c @@ -0,0 +1,282 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * SMP support for pSeries machines. + * + * Dave Engebretsen, Peter Bergner, and + * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com + * + * Plus various changes from other IBM teams... + */ + + +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/smp.h> +#include <linux/interrupt.h> +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/spinlock.h> +#include <linux/cache.h> +#include <linux/err.h> +#include <linux/device.h> +#include <linux/cpu.h> +#include <linux/pgtable.h> + +#include <asm/ptrace.h> +#include <linux/atomic.h> +#include <asm/irq.h> +#include <asm/page.h> +#include <asm/io.h> +#include <asm/smp.h> +#include <asm/paca.h> +#include <asm/machdep.h> +#include <asm/cputable.h> +#include <asm/firmware.h> +#include <asm/rtas.h> +#include <asm/vdso_datapage.h> +#include <asm/cputhreads.h> +#include <asm/xics.h> +#include <asm/xive.h> +#include <asm/dbell.h> +#include <asm/plpar_wrappers.h> +#include <asm/code-patching.h> +#include <asm/svm.h> +#include <asm/kvm_guest.h> + +#include "pseries.h" + +/* + * The Primary thread of each non-boot processor was started from the OF client + * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop. + */ +static cpumask_var_t of_spin_mask; + +/* Query where a cpu is now. Return codes #defined in plpar_wrappers.h */ +int smp_query_cpu_stopped(unsigned int pcpu) +{ + int cpu_status, status; + int qcss_tok = rtas_function_token(RTAS_FN_QUERY_CPU_STOPPED_STATE); + + if (qcss_tok == RTAS_UNKNOWN_SERVICE) { + printk_once(KERN_INFO + "Firmware doesn't support query-cpu-stopped-state\n"); + return QCSS_HARDWARE_ERROR; + } + + status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu); + if (status != 0) { + printk(KERN_ERR + "RTAS query-cpu-stopped-state failed: %i\n", status); + return status; + } + + return cpu_status; +} + +/** + * smp_startup_cpu() - start the given cpu + * + * At boot time, there is nothing to do for primary threads which were + * started from Open Firmware. For anything else, call RTAS with the + * appropriate start location. + * + * Returns: + * 0 - failure + * 1 - success + */ +static inline int smp_startup_cpu(unsigned int lcpu) +{ + int status; + unsigned long start_here = + __pa(ppc_function_entry(generic_secondary_smp_init)); + unsigned int pcpu; + int start_cpu; + + if (cpumask_test_cpu(lcpu, of_spin_mask)) + /* Already started by OF and sitting in spin loop */ + return 1; + + pcpu = get_hard_smp_processor_id(lcpu); + + /* Check to see if the CPU out of FW already for kexec */ + if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){ + cpumask_set_cpu(lcpu, of_spin_mask); + return 1; + } + + /* + * If the RTAS start-cpu token does not exist then presume the + * cpu is already spinning. + */ + start_cpu = rtas_function_token(RTAS_FN_START_CPU); + if (start_cpu == RTAS_UNKNOWN_SERVICE) + return 1; + + status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu); + if (status != 0) { + printk(KERN_ERR "start-cpu failed: %i\n", status); + return 0; + } + + return 1; +} + +static void smp_setup_cpu(int cpu) +{ + if (xive_enabled()) + xive_smp_setup_cpu(); + else if (cpu != boot_cpuid) + xics_setup_cpu(); + + if (firmware_has_feature(FW_FEATURE_SPLPAR)) + vpa_init(cpu); + + cpumask_clear_cpu(cpu, of_spin_mask); +} + +static int smp_pSeries_kick_cpu(int nr) +{ + if (nr < 0 || nr >= nr_cpu_ids) + return -EINVAL; + + if (!smp_startup_cpu(nr)) + return -ENOENT; + + /* + * The processor is currently spinning, waiting for the + * cpu_start field to become non-zero After we set cpu_start, + * the processor will continue on to secondary_start + */ + paca_ptrs[nr]->cpu_start = 1; + + return 0; +} + +static int pseries_smp_prepare_cpu(int cpu) +{ + if (xive_enabled()) + return xive_smp_prepare_cpu(cpu); + return 0; +} + +/* Cause IPI as setup by the interrupt controller (xics or xive) */ +static void (*ic_cause_ipi)(int cpu) __ro_after_init; + +/* Use msgsndp doorbells target is a sibling, else use interrupt controller */ +static void dbell_or_ic_cause_ipi(int cpu) +{ + if (doorbell_try_core_ipi(cpu)) + return; + + ic_cause_ipi(cpu); +} + +static int pseries_cause_nmi_ipi(int cpu) +{ + int hwcpu; + + if (cpu == NMI_IPI_ALL_OTHERS) { + hwcpu = H_SIGNAL_SYS_RESET_ALL_OTHERS; + } else { + if (cpu < 0) { + WARN_ONCE(true, "incorrect cpu parameter %d", cpu); + return 0; + } + + hwcpu = get_hard_smp_processor_id(cpu); + } + + if (plpar_signal_sys_reset(hwcpu) == H_SUCCESS) + return 1; + + return 0; +} + +static __init void pSeries_smp_probe(void) +{ + if (xive_enabled()) + xive_smp_probe(); + else + xics_smp_probe(); + + /* No doorbell facility, must use the interrupt controller for IPIs */ + if (!cpu_has_feature(CPU_FTR_DBELL)) + return; + + /* Doorbells can only be used for IPIs between SMT siblings */ + if (!cpu_has_feature(CPU_FTR_SMT)) + return; + + check_kvm_guest(); + + if (is_kvm_guest()) { + /* + * KVM emulates doorbells by disabling FSCR[MSGP] so msgsndp + * faults to the hypervisor which then reads the instruction + * from guest memory, which tends to be slower than using XIVE. + */ + if (xive_enabled()) + return; + + /* + * XICS hcalls aren't as fast, so we can use msgsndp (which + * also helps exercise KVM emulation), however KVM can't + * emulate secure guests because it can't read the instruction + * out of their memory. + */ + if (is_secure_guest()) + return; + } + + /* + * Under PowerVM, FSCR[MSGP] is enabled as guest vCPU siblings are + * gang scheduled on the same physical core, so doorbells are always + * faster than the interrupt controller, and they can be used by + * secure guests. + */ + + ic_cause_ipi = smp_ops->cause_ipi; + smp_ops->cause_ipi = dbell_or_ic_cause_ipi; +} + +static struct smp_ops_t pseries_smp_ops = { + .message_pass = NULL, /* Use smp_muxed_ipi_message_pass */ + .cause_ipi = NULL, /* Filled at runtime by pSeries_smp_probe() */ + .cause_nmi_ipi = pseries_cause_nmi_ipi, + .probe = pSeries_smp_probe, + .prepare_cpu = pseries_smp_prepare_cpu, + .kick_cpu = smp_pSeries_kick_cpu, + .setup_cpu = smp_setup_cpu, + .cpu_bootable = smp_generic_cpu_bootable, +}; + +/* This is called very early */ +void __init smp_init_pseries(void) +{ + int i; + + pr_debug(" -> smp_init_pSeries()\n"); + smp_ops = &pseries_smp_ops; + + alloc_bootmem_cpumask_var(&of_spin_mask); + + /* + * Mark threads which are still spinning in hold loops + * + * We know prom_init will not have started them if RTAS supports + * query-cpu-stopped-state. + */ + if (rtas_function_token(RTAS_FN_QUERY_CPU_STOPPED_STATE) == RTAS_UNKNOWN_SERVICE) { + if (cpu_has_feature(CPU_FTR_SMT)) { + for_each_present_cpu(i) { + if (cpu_thread_in_core(i) == 0) + cpumask_set_cpu(i, of_spin_mask); + } + } else + cpumask_copy(of_spin_mask, cpu_present_mask); + + cpumask_clear_cpu(boot_cpuid, of_spin_mask); + } + + pr_debug(" <- smp_init_pSeries()\n"); +} |