1 files changed, 288 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/smp.c b/arch/powerpc/platforms/pseries/smp.c
new file mode 100644
index 000000000..fd2174edf
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/smp.c
@@ -0,0 +1,288 @@
+// 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_token("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_token("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_token("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);
+	}
+
+	/* Non-lpar has additional take/give timebase */
+	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
+		smp_ops->give_timebase = rtas_give_timebase;
+		smp_ops->take_timebase = rtas_take_timebase;
+	}
+
+	pr_debug(" <- smp_init_pSeries()\n");
+}