1 files changed, 441 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
new file mode 100644
index 000000000..9e1a25398
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -0,0 +1,441 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * SMP support for PowerNV machines.
+ *
+ * Copyright 2011 IBM Corp.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/sched/hotplug.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/cpu.h>
+
+#include <asm/irq.h>
+#include <asm/smp.h>
+#include <asm/paca.h>
+#include <asm/machdep.h>
+#include <asm/cputable.h>
+#include <asm/firmware.h>
+#include <asm/vdso_datapage.h>
+#include <asm/cputhreads.h>
+#include <asm/xics.h>
+#include <asm/xive.h>
+#include <asm/opal.h>
+#include <asm/runlatch.h>
+#include <asm/code-patching.h>
+#include <asm/dbell.h>
+#include <asm/kvm_ppc.h>
+#include <asm/ppc-opcode.h>
+#include <asm/cpuidle.h>
+#include <asm/kexec.h>
+#include <asm/reg.h>
+#include <asm/powernv.h>
+
+#include "powernv.h"
+
+#ifdef DEBUG
+#include <asm/udbg.h>
+#define DBG(fmt...) udbg_printf(fmt)
+#else
+#define DBG(fmt...) do { } while (0)
+#endif
+
+static void pnv_smp_setup_cpu(int cpu)
+{
+	/*
+	 * P9 workaround for CI vector load (see traps.c),
+	 * enable the corresponding HMI interrupt
+	 */
+	if (pvr_version_is(PVR_POWER9))
+		mtspr(SPRN_HMEER, mfspr(SPRN_HMEER) | PPC_BIT(17));
+
+	if (xive_enabled())
+		xive_smp_setup_cpu();
+	else if (cpu != boot_cpuid)
+		xics_setup_cpu();
+}
+
+static int pnv_smp_kick_cpu(int nr)
+{
+	unsigned int pcpu;
+	unsigned long start_here =
+			__pa(ppc_function_entry(generic_secondary_smp_init));
+	long rc;
+	uint8_t status;
+
+	if (nr < 0 || nr >= nr_cpu_ids)
+		return -EINVAL;
+
+	pcpu = get_hard_smp_processor_id(nr);
+	/*
+	 * If we already started or OPAL is not supported, we just
+	 * kick the CPU via the PACA
+	 */
+	if (paca_ptrs[nr]->cpu_start || !firmware_has_feature(FW_FEATURE_OPAL))
+		goto kick;
+
+	/*
+	 * At this point, the CPU can either be spinning on the way in
+	 * from kexec or be inside OPAL waiting to be started for the
+	 * first time. OPAL v3 allows us to query OPAL to know if it
+	 * has the CPUs, so we do that
+	 */
+	rc = opal_query_cpu_status(pcpu, &status);
+	if (rc != OPAL_SUCCESS) {
+		pr_warn("OPAL Error %ld querying CPU %d state\n", rc, nr);
+		return -ENODEV;
+	}
+
+	/*
+	 * Already started, just kick it, probably coming from
+	 * kexec and spinning
+	 */
+	if (status == OPAL_THREAD_STARTED)
+		goto kick;
+
+	/*
+	 * Available/inactive, let's kick it
+	 */
+	if (status == OPAL_THREAD_INACTIVE) {
+		pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", nr, pcpu);
+		rc = opal_start_cpu(pcpu, start_here);
+		if (rc != OPAL_SUCCESS) {
+			pr_warn("OPAL Error %ld starting CPU %d\n", rc, nr);
+			return -ENODEV;
+		}
+	} else {
+		/*
+		 * An unavailable CPU (or any other unknown status)
+		 * shouldn't be started. It should also
+		 * not be in the possible map but currently it can
+		 * happen
+		 */
+		pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable"
+			 " (status %d)...\n", nr, pcpu, status);
+		return -ENODEV;
+	}
+
+kick:
+	return smp_generic_kick_cpu(nr);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+static int pnv_smp_cpu_disable(void)
+{
+	int cpu = smp_processor_id();
+
+	/* This is identical to pSeries... might consolidate by
+	 * moving migrate_irqs_away to a ppc_md with default to
+	 * the generic fixup_irqs. --BenH.
+	 */
+	set_cpu_online(cpu, false);
+	vdso_data->processorCount--;
+	if (cpu == boot_cpuid)
+		boot_cpuid = cpumask_any(cpu_online_mask);
+	if (xive_enabled())
+		xive_smp_disable_cpu();
+	else
+		xics_migrate_irqs_away();
+
+	cleanup_cpu_mmu_context();
+
+	return 0;
+}
+
+static void pnv_flush_interrupts(void)
+{
+	if (cpu_has_feature(CPU_FTR_ARCH_300)) {
+		if (xive_enabled())
+			xive_flush_interrupt();
+		else
+			icp_opal_flush_interrupt();
+	} else {
+		icp_native_flush_interrupt();
+	}
+}
+
+static void pnv_cpu_offline_self(void)
+{
+	unsigned long srr1, unexpected_mask, wmask;
+	unsigned int cpu;
+	u64 lpcr_val;
+
+	/* Standard hot unplug procedure */
+
+	idle_task_exit();
+	cpu = smp_processor_id();
+	DBG("CPU%d offline\n", cpu);
+	generic_set_cpu_dead(cpu);
+	smp_wmb();
+
+	wmask = SRR1_WAKEMASK;
+	if (cpu_has_feature(CPU_FTR_ARCH_207S))
+		wmask = SRR1_WAKEMASK_P8;
+
+	/*
+	 * This turns the irq soft-disabled state we're called with, into a
+	 * hard-disabled state with pending irq_happened interrupts cleared.
+	 *
+	 * PACA_IRQ_DEC   - Decrementer should be ignored.
+	 * PACA_IRQ_HMI   - Can be ignored, processing is done in real mode.
+	 * PACA_IRQ_DBELL, EE, PMI - Unexpected.
+	 */
+	hard_irq_disable();
+	if (generic_check_cpu_restart(cpu))
+		goto out;
+
+	unexpected_mask = ~(PACA_IRQ_DEC | PACA_IRQ_HMI | PACA_IRQ_HARD_DIS);
+	if (local_paca->irq_happened & unexpected_mask) {
+		if (local_paca->irq_happened & PACA_IRQ_EE)
+			pnv_flush_interrupts();
+		DBG("CPU%d Unexpected exit while offline irq_happened=%lx!\n",
+				cpu, local_paca->irq_happened);
+	}
+	local_paca->irq_happened = PACA_IRQ_HARD_DIS;
+
+	/*
+	 * We don't want to take decrementer interrupts while we are
+	 * offline, so clear LPCR:PECE1. We keep PECE2 (and
+	 * LPCR_PECE_HVEE on P9) enabled so as to let IPIs in.
+	 *
+	 * If the CPU gets woken up by a special wakeup, ensure that
+	 * the SLW engine sets LPCR with decrementer bit cleared, else
+	 * the CPU will come back to the kernel due to a spurious
+	 * wakeup.
+	 */
+	lpcr_val = mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1;
+	pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val);
+
+	while (!generic_check_cpu_restart(cpu)) {
+		/*
+		 * Clear IPI flag, since we don't handle IPIs while
+		 * offline, except for those when changing micro-threading
+		 * mode, which are handled explicitly below, and those
+		 * for coming online, which are handled via
+		 * generic_check_cpu_restart() calls.
+		 */
+		kvmppc_clear_host_ipi(cpu);
+
+		srr1 = pnv_cpu_offline(cpu);
+
+		WARN_ON_ONCE(!irqs_disabled());
+		WARN_ON(lazy_irq_pending());
+
+		/*
+		 * If the SRR1 value indicates that we woke up due to
+		 * an external interrupt, then clear the interrupt.
+		 * We clear the interrupt before checking for the
+		 * reason, so as to avoid a race where we wake up for
+		 * some other reason, find nothing and clear the interrupt
+		 * just as some other cpu is sending us an interrupt.
+		 * If we returned from power7_nap as a result of
+		 * having finished executing in a KVM guest, then srr1
+		 * contains 0.
+		 */
+		if (((srr1 & wmask) == SRR1_WAKEEE) ||
+		    ((srr1 & wmask) == SRR1_WAKEHVI)) {
+			pnv_flush_interrupts();
+		} else if ((srr1 & wmask) == SRR1_WAKEHDBELL) {
+			unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
+			asm volatile(PPC_MSGCLR(%0) : : "r" (msg));
+		} else if ((srr1 & wmask) == SRR1_WAKERESET) {
+			irq_set_pending_from_srr1(srr1);
+			/* Does not return */
+		}
+
+		smp_mb();
+
+		/*
+		 * For kdump kernels, we process the ipi and jump to
+		 * crash_ipi_callback
+		 */
+		if (kdump_in_progress()) {
+			/*
+			 * If we got to this point, we've not used
+			 * NMI's, otherwise we would have gone
+			 * via the SRR1_WAKERESET path. We are
+			 * using regular IPI's for waking up offline
+			 * threads.
+			 */
+			struct pt_regs regs;
+
+			ppc_save_regs(&regs);
+			crash_ipi_callback(&regs);
+			/* Does not return */
+		}
+
+		if (cpu_core_split_required())
+			continue;
+
+		if (srr1 && !generic_check_cpu_restart(cpu))
+			DBG("CPU%d Unexpected exit while offline srr1=%lx!\n",
+					cpu, srr1);
+
+	}
+
+	/*
+	 * Re-enable decrementer interrupts in LPCR.
+	 *
+	 * Further, we want stop states to be woken up by decrementer
+	 * for non-hotplug cases. So program the LPCR via stop api as
+	 * well.
+	 */
+	lpcr_val = mfspr(SPRN_LPCR) | (u64)LPCR_PECE1;
+	pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val);
+out:
+	DBG("CPU%d coming online...\n", cpu);
+}
+
+#endif /* CONFIG_HOTPLUG_CPU */
+
+static int pnv_cpu_bootable(unsigned int nr)
+{
+	/*
+	 * Starting with POWER8, the subcore logic relies on all threads of a
+	 * core being booted so that they can participate in split mode
+	 * switches. So on those machines we ignore the smt_enabled_at_boot
+	 * setting (smt-enabled on the kernel command line).
+	 */
+	if (cpu_has_feature(CPU_FTR_ARCH_207S))
+		return 1;
+
+	return smp_generic_cpu_bootable(nr);
+}
+
+static int pnv_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);
+
+static void pnv_cause_ipi(int cpu)
+{
+	if (doorbell_try_core_ipi(cpu))
+		return;
+
+	ic_cause_ipi(cpu);
+}
+
+static void __init pnv_smp_probe(void)
+{
+	if (xive_enabled())
+		xive_smp_probe();
+	else
+		xics_smp_probe();
+
+	if (cpu_has_feature(CPU_FTR_DBELL)) {
+		ic_cause_ipi = smp_ops->cause_ipi;
+		WARN_ON(!ic_cause_ipi);
+
+		if (cpu_has_feature(CPU_FTR_ARCH_300))
+			smp_ops->cause_ipi = doorbell_global_ipi;
+		else
+			smp_ops->cause_ipi = pnv_cause_ipi;
+	}
+}
+
+noinstr static int pnv_system_reset_exception(struct pt_regs *regs)
+{
+	if (smp_handle_nmi_ipi(regs))
+		return 1;
+	return 0;
+}
+
+static int pnv_cause_nmi_ipi(int cpu)
+{
+	int64_t rc;
+
+	if (cpu >= 0) {
+		int h = get_hard_smp_processor_id(cpu);
+
+		if (opal_check_token(OPAL_QUIESCE))
+			opal_quiesce(QUIESCE_HOLD, h);
+
+		rc = opal_signal_system_reset(h);
+
+		if (opal_check_token(OPAL_QUIESCE))
+			opal_quiesce(QUIESCE_RESUME, h);
+
+		if (rc != OPAL_SUCCESS)
+			return 0;
+		return 1;
+
+	} else if (cpu == NMI_IPI_ALL_OTHERS) {
+		bool success = true;
+		int c;
+
+		if (opal_check_token(OPAL_QUIESCE))
+			opal_quiesce(QUIESCE_HOLD, -1);
+
+		/*
+		 * We do not use broadcasts (yet), because it's not clear
+		 * exactly what semantics Linux wants or the firmware should
+		 * provide.
+		 */
+		for_each_online_cpu(c) {
+			if (c == smp_processor_id())
+				continue;
+
+			rc = opal_signal_system_reset(
+						get_hard_smp_processor_id(c));
+			if (rc != OPAL_SUCCESS)
+				success = false;
+		}
+
+		if (opal_check_token(OPAL_QUIESCE))
+			opal_quiesce(QUIESCE_RESUME, -1);
+
+		if (success)
+			return 1;
+
+		/*
+		 * Caller will fall back to doorbells, which may pick
+		 * up the remainders.
+		 */
+	}
+
+	return 0;
+}
+
+static struct smp_ops_t pnv_smp_ops = {
+	.message_pass	= NULL, /* Use smp_muxed_ipi_message_pass */
+	.cause_ipi	= NULL,	/* Filled at runtime by pnv_smp_probe() */
+	.cause_nmi_ipi	= NULL,
+	.probe		= pnv_smp_probe,
+	.prepare_cpu	= pnv_smp_prepare_cpu,
+	.kick_cpu	= pnv_smp_kick_cpu,
+	.setup_cpu	= pnv_smp_setup_cpu,
+	.cpu_bootable	= pnv_cpu_bootable,
+#ifdef CONFIG_HOTPLUG_CPU
+	.cpu_disable	= pnv_smp_cpu_disable,
+	.cpu_die	= generic_cpu_die,
+	.cpu_offline_self = pnv_cpu_offline_self,
+#endif /* CONFIG_HOTPLUG_CPU */
+};
+
+/* This is called very early during platform setup_arch */
+void __init pnv_smp_init(void)
+{
+	if (opal_check_token(OPAL_SIGNAL_SYSTEM_RESET)) {
+		ppc_md.system_reset_exception = pnv_system_reset_exception;
+		pnv_smp_ops.cause_nmi_ipi = pnv_cause_nmi_ipi;
+	}
+	smp_ops = &pnv_smp_ops;
+
+#ifdef CONFIG_HOTPLUG_CPU
+#ifdef CONFIG_KEXEC_CORE
+	crash_wake_offline = 1;
+#endif
+#endif
+}