diff options
Diffstat (limited to 'arch/powerpc/platforms')
| -rw-r--r-- | arch/powerpc/platforms/powernv/Makefile | 2 | ||||
| -rw-r--r-- | arch/powerpc/platforms/powernv/powernv.h | 2 | ||||
| -rw-r--r-- | arch/powerpc/platforms/powernv/smp.c | 18 | ||||
| -rw-r--r-- | arch/powerpc/platforms/powernv/subcore-asm.S | 95 | ||||
| -rw-r--r-- | arch/powerpc/platforms/powernv/subcore.c | 392 | ||||
| -rw-r--r-- | arch/powerpc/platforms/powernv/subcore.h | 18 |
6 files changed, 518 insertions, 9 deletions
diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile index 63cebb9b4d45..4ad0d345bc96 100644 --- a/arch/powerpc/platforms/powernv/Makefile +++ b/arch/powerpc/platforms/powernv/Makefile @@ -1,7 +1,7 @@ obj-y += setup.o opal-takeover.o opal-wrappers.o opal.o opal-async.o obj-y += opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o obj-y += rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o -obj-y += opal-msglog.o +obj-y += opal-msglog.o subcore.o subcore-asm.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_PCI) += pci.o pci-p5ioc2.o pci-ioda.o diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h index 0051e108ef0f..75501bfede7f 100644 --- a/arch/powerpc/platforms/powernv/powernv.h +++ b/arch/powerpc/platforms/powernv/powernv.h @@ -25,4 +25,6 @@ static inline int pnv_pci_dma_set_mask(struct pci_dev *pdev, u64 dma_mask) extern void pnv_lpc_init(void); +bool cpu_core_split_required(void); + #endif /* _POWERNV_H */ diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c index 65faf998fe2c..0062a43a2e0d 100644 --- a/arch/powerpc/platforms/powernv/smp.c +++ b/arch/powerpc/platforms/powernv/smp.c @@ -161,15 +161,17 @@ static void pnv_smp_cpu_kill_self(void) ppc64_runlatch_off(); power7_nap(1); ppc64_runlatch_on(); - if (!generic_check_cpu_restart(cpu)) { + + /* Reenable IRQs briefly to clear the IPI that woke us */ + local_irq_enable(); + local_irq_disable(); + mb(); + + if (cpu_core_split_required()) + continue; + + if (!generic_check_cpu_restart(cpu)) DBG("CPU%d Unexpected exit while offline !\n", cpu); - /* We may be getting an IPI, so we re-enable - * interrupts to process it, it will be ignored - * since we aren't online (hopefully) - */ - local_irq_enable(); - local_irq_disable(); - } } mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1); DBG("CPU%d coming online...\n", cpu); diff --git a/arch/powerpc/platforms/powernv/subcore-asm.S b/arch/powerpc/platforms/powernv/subcore-asm.S new file mode 100644 index 000000000000..39bb24aa8f34 --- /dev/null +++ b/arch/powerpc/platforms/powernv/subcore-asm.S @@ -0,0 +1,95 @@ +/* + * Copyright 2013, Michael (Ellerman|Neuling), IBM Corporation. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <asm/asm-offsets.h> +#include <asm/ppc_asm.h> +#include <asm/reg.h> + +#include "subcore.h" + + +_GLOBAL(split_core_secondary_loop) + /* + * r3 = u8 *state, used throughout the routine + * r4 = temp + * r5 = temp + * .. + * r12 = MSR + */ + mfmsr r12 + + /* Disable interrupts so SRR0/1 don't get trashed */ + li r4,0 + ori r4,r4,MSR_EE|MSR_SE|MSR_BE|MSR_RI + andc r4,r12,r4 + sync + mtmsrd r4 + + /* Switch to real mode and leave interrupts off */ + li r5, MSR_IR|MSR_DR + andc r5, r4, r5 + + LOAD_REG_ADDR(r4, real_mode) + + mtspr SPRN_SRR0,r4 + mtspr SPRN_SRR1,r5 + rfid + b . /* prevent speculative execution */ + +real_mode: + /* Grab values from unsplit SPRs */ + mfspr r6, SPRN_LDBAR + mfspr r7, SPRN_PMMAR + mfspr r8, SPRN_PMCR + mfspr r9, SPRN_RPR + mfspr r10, SPRN_SDR1 + + /* Order reading the SPRs vs telling the primary we are ready to split */ + sync + + /* Tell thread 0 we are in real mode */ + li r4, SYNC_STEP_REAL_MODE + stb r4, 0(r3) + + li r5, (HID0_POWER8_4LPARMODE | HID0_POWER8_2LPARMODE)@highest + sldi r5, r5, 48 + + /* Loop until we see the split happen in HID0 */ +1: mfspr r4, SPRN_HID0 + and. r4, r4, r5 + beq 1b + + /* + * We only need to initialise the below regs once for each subcore, + * but it's simpler and harmless to do it on each thread. + */ + + /* Make sure various SPRS have sane values */ + li r4, 0 + mtspr SPRN_LPID, r4 + mtspr SPRN_PCR, r4 + mtspr SPRN_HDEC, r4 + + /* Restore SPR values now we are split */ + mtspr SPRN_LDBAR, r6 + mtspr SPRN_PMMAR, r7 + mtspr SPRN_PMCR, r8 + mtspr SPRN_RPR, r9 + mtspr SPRN_SDR1, r10 + + LOAD_REG_ADDR(r5, virtual_mode) + + /* Get out of real mode */ + mtspr SPRN_SRR0,r5 + mtspr SPRN_SRR1,r12 + rfid + b . /* prevent speculative execution */ + +virtual_mode: + blr diff --git a/arch/powerpc/platforms/powernv/subcore.c b/arch/powerpc/platforms/powernv/subcore.c new file mode 100644 index 000000000000..894ecb3eb596 --- /dev/null +++ b/arch/powerpc/platforms/powernv/subcore.c @@ -0,0 +1,392 @@ +/* + * Copyright 2013, Michael (Ellerman|Neuling), IBM Corporation. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#define pr_fmt(fmt) "powernv: " fmt + +#include <linux/kernel.h> +#include <linux/cpu.h> +#include <linux/cpumask.h> +#include <linux/device.h> +#include <linux/gfp.h> +#include <linux/smp.h> +#include <linux/stop_machine.h> + +#include <asm/cputhreads.h> +#include <asm/kvm_ppc.h> +#include <asm/machdep.h> +#include <asm/opal.h> +#include <asm/smp.h> + +#include "subcore.h" + + +/* + * Split/unsplit procedure: + * + * A core can be in one of three states, unsplit, 2-way split, and 4-way split. + * + * The mapping to subcores_per_core is simple: + * + * State | subcores_per_core + * ------------|------------------ + * Unsplit | 1 + * 2-way split | 2 + * 4-way split | 4 + * + * The core is split along thread boundaries, the mapping between subcores and + * threads is as follows: + * + * Unsplit: + * ---------------------------- + * Subcore | 0 | + * ---------------------------- + * Thread | 0 1 2 3 4 5 6 7 | + * ---------------------------- + * + * 2-way split: + * ------------------------------------- + * Subcore | 0 | 1 | + * ------------------------------------- + * Thread | 0 1 2 3 | 4 5 6 7 | + * ------------------------------------- + * + * 4-way split: + * ----------------------------------------- + * Subcore | 0 | 1 | 2 | 3 | + * ----------------------------------------- + * Thread | 0 1 | 2 3 | 4 5 | 6 7 | + * ----------------------------------------- + * + * + * Transitions + * ----------- + * + * It is not possible to transition between either of the split states, the + * core must first be unsplit. The legal transitions are: + * + * ----------- --------------- + * | | <----> | 2-way split | + * | | --------------- + * | Unsplit | + * | | --------------- + * | | <----> | 4-way split | + * ----------- --------------- + * + * Unsplitting + * ----------- + * + * Unsplitting is the simpler procedure. It requires thread 0 to request the + * unsplit while all other threads NAP. + * + * Thread 0 clears HID0_POWER8_DYNLPARDIS (Dynamic LPAR Disable). This tells + * the hardware that if all threads except 0 are napping, the hardware should + * unsplit the core. + * + * Non-zero threads are sent to a NAP loop, they don't exit the loop until they + * see the core unsplit. + * + * Core 0 spins waiting for the hardware to see all the other threads napping + * and perform the unsplit. + * + * Once thread 0 sees the unsplit, it IPIs the secondary threads to wake them + * out of NAP. They will then see the core unsplit and exit the NAP loop. + * + * Splitting + * --------- + * + * The basic splitting procedure is fairly straight forward. However it is + * complicated by the fact that after the split occurs, the newly created + * subcores are not in a fully initialised state. + * + * Most notably the subcores do not have the correct value for SDR1, which + * means they must not be running in virtual mode when the split occurs. The + * subcores have separate timebases SPRs but these are pre-synchronised by + * opal. + * + * To begin with secondary threads are sent to an assembly routine. There they + * switch to real mode, so they are immune to the uninitialised SDR1 value. + * Once in real mode they indicate that they are in real mode, and spin waiting + * to see the core split. + * + * Thread 0 waits to see that all secondaries are in real mode, and then begins + * the splitting procedure. It firstly sets HID0_POWER8_DYNLPARDIS, which + * prevents the hardware from unsplitting. Then it sets the appropriate HID bit + * to request the split, and spins waiting to see that the split has happened. + * + * Concurrently the secondaries will notice the split. When they do they set up + * their SPRs, notably SDR1, and then they can return to virtual mode and exit + * the procedure. + */ + +/* Initialised at boot by subcore_init() */ +static int subcores_per_core; + +/* + * Used to communicate to offline cpus that we want them to pop out of the + * offline loop and do a split or unsplit. + * + * 0 - no split happening + * 1 - unsplit in progress + * 2 - split to 2 in progress + * 4 - split to 4 in progress + */ +static int new_split_mode; + +static cpumask_var_t cpu_offline_mask; + +struct split_state { + u8 step; + u8 master; +}; + +static DEFINE_PER_CPU(struct split_state, split_state); + +static void wait_for_sync_step(int step) +{ + int i, cpu = smp_processor_id(); + + for (i = cpu + 1; i < cpu + threads_per_core; i++) + while(per_cpu(split_state, i).step < step) + barrier(); + + /* Order the wait loop vs any subsequent loads/stores. */ + mb(); +} + +static void unsplit_core(void) +{ + u64 hid0, mask; + int i, cpu; + + mask = HID0_POWER8_2LPARMODE | HID0_POWER8_4LPARMODE; + + cpu = smp_processor_id(); + if (cpu_thread_in_core(cpu) != 0) { + while (mfspr(SPRN_HID0) & mask) + power7_nap(0); + + per_cpu(split_state, cpu).step = SYNC_STEP_UNSPLIT; + return; + } + + hid0 = mfspr(SPRN_HID0); + hid0 &= ~HID0_POWER8_DYNLPARDIS; + mtspr(SPRN_HID0, hid0); + + while (mfspr(SPRN_HID0) & mask) + cpu_relax(); + + /* Wake secondaries out of NAP */ + for (i = cpu + 1; i < cpu + threads_per_core; i++) + smp_send_reschedule(i); + + wait_for_sync_step(SYNC_STEP_UNSPLIT); +} + +static void split_core(int new_mode) +{ + struct { u64 value; u64 mask; } split_parms[2] = { + { HID0_POWER8_1TO2LPAR, HID0_POWER8_2LPARMODE }, + { HID0_POWER8_1TO4LPAR, HID0_POWER8_4LPARMODE } + }; + int i, cpu; + u64 hid0; + + /* Convert new_mode (2 or 4) into an index into our parms array */ + i = (new_mode >> 1) - 1; + BUG_ON(i < 0 || i > 1); + + cpu = smp_processor_id(); + if (cpu_thread_in_core(cpu) != 0) { + split_core_secondary_loop(&per_cpu(split_state, cpu).step); + return; + } + + wait_for_sync_step(SYNC_STEP_REAL_MODE); + + /* Write new mode */ + hid0 = mfspr(SPRN_HID0); + hid0 |= HID0_POWER8_DYNLPARDIS | split_parms[i].value; + mtspr(SPRN_HID0, hid0); + + /* Wait for it to happen */ + while (!(mfspr(SPRN_HID0) & split_parms[i].mask)) + cpu_relax(); +} + +static void cpu_do_split(int new_mode) +{ + /* + * At boot subcores_per_core will be 0, so we will always unsplit at + * boot. In the usual case where the core is already unsplit it's a + * nop, and this just ensures the kernel's notion of the mode is + * consistent with the hardware. + */ + if (subcores_per_core != 1) + unsplit_core(); + + if (new_mode != 1) + split_core(new_mode); + + mb(); + per_cpu(split_state, smp_processor_id()).step = SYNC_STEP_FINISHED; +} + +bool cpu_core_split_required(void) +{ + smp_rmb(); + + if (!new_split_mode) + return false; + + cpu_do_split(new_split_mode); + + return true; +} + +static int cpu_update_split_mode(void *data) +{ + int cpu, new_mode = *(int *)data; + + if (this_cpu_ptr(&split_state)->master) { + new_split_mode = new_mode; + smp_wmb(); + + cpumask_andnot(cpu_offline_mask, cpu_present_mask, + cpu_online_mask); + + /* This should work even though the cpu is offline */ + for_each_cpu(cpu, cpu_offline_mask) + smp_send_reschedule(cpu); + } + + cpu_do_split(new_mode); + + if (this_cpu_ptr(&split_state)->master) { + /* Wait for all cpus to finish before we touch subcores_per_core */ + for_each_present_cpu(cpu) { + if (cpu >= setup_max_cpus) + break; + + while(per_cpu(split_state, cpu).step < SYNC_STEP_FINISHED) + barrier(); + } + + new_split_mode = 0; + + /* Make the new mode public */ + subcores_per_core = new_mode; + threads_per_subcore = threads_per_core / subcores_per_core; + + /* Make sure the new mode is written before we exit */ + mb(); + } + + return 0; +} + +static int set_subcores_per_core(int new_mode) +{ + struct split_state *state; + int cpu; + + if (kvm_hv_mode_active()) { + pr_err("Unable to change split core mode while KVM active.\n"); + return -EBUSY; + } + + /* + * We are only called at boot, or from the sysfs write. If that ever + * changes we'll need a lock here. + */ + BUG_ON(new_mode < 1 || new_mode > 4 || new_mode == 3); + + for_each_present_cpu(cpu) { + state = &per_cpu(split_state, cpu); + state->step = SYNC_STEP_INITIAL; + state->master = 0; + } + + get_online_cpus(); + + /* This cpu will update the globals before exiting stop machine */ + this_cpu_ptr(&split_state)->master = 1; + + /* Ensure state is consistent before we call the other cpus */ + mb(); + + stop_machine(cpu_update_split_mode, &new_mode, cpu_online_mask); + + put_online_cpus(); + + return 0; +} + +static ssize_t __used store_subcores_per_core(struct device *dev, + struct device_attribute *attr, const char *buf, + size_t count) +{ + unsigned long val; + int rc; + + /* We are serialised by the attribute lock */ + + rc = sscanf(buf, "%lx", &val); + if (rc != 1) + return -EINVAL; + + switch (val) { + case 1: + case 2: + case 4: + if (subcores_per_core == val) + /* Nothing to do */ + goto out; + break; + default: + return -EINVAL; + } + + rc = set_subcores_per_core(val); + if (rc) + return rc; + +out: + return count; +} + +static ssize_t show_subcores_per_core(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sprintf(buf, "%x\n", subcores_per_core); +} + +static DEVICE_ATTR(subcores_per_core, 0644, + show_subcores_per_core, store_subcores_per_core); + +static int subcore_init(void) +{ + if (!cpu_has_feature(CPU_FTR_ARCH_207S)) + return 0; + + /* + * We need all threads in a core to be present to split/unsplit so + * continue only if max_cpus are aligned to threads_per_core. + */ + if (setup_max_cpus % threads_per_core) + return 0; + + BUG_ON(!alloc_cpumask_var(&cpu_offline_mask, GFP_KERNEL)); + + set_subcores_per_core(1); + + return device_create_file(cpu_subsys.dev_root, + &dev_attr_subcores_per_core); +} +machine_device_initcall(powernv, subcore_init); diff --git a/arch/powerpc/platforms/powernv/subcore.h b/arch/powerpc/platforms/powernv/subcore.h new file mode 100644 index 000000000000..148abc91debf --- /dev/null +++ b/arch/powerpc/platforms/powernv/subcore.h @@ -0,0 +1,18 @@ +/* + * Copyright 2013, Michael Ellerman, IBM Corporation. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +/* These are ordered and tested with <= */ +#define SYNC_STEP_INITIAL 0 +#define SYNC_STEP_UNSPLIT 1 /* Set by secondary when it sees unsplit */ +#define SYNC_STEP_REAL_MODE 2 /* Set by secondary when in real mode */ +#define SYNC_STEP_FINISHED 3 /* Set by secondary when split/unsplit is done */ + +#ifndef __ASSEMBLY__ +void split_core_secondary_loop(u8 *state); +#endif |