X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fx86_64%2Fkernel%2Fsmp-xen.c;fp=arch%2Fx86_64%2Fkernel%2Fsmp-xen.c;h=1b9fad1bde2cbe42dcc3aeb4f76065297ba91234;hb=1db395853d4f30d6120458bd279ede1f882a8525;hp=0000000000000000000000000000000000000000;hpb=34a75f0025b9cf803b6a88db032e6ad6950c9313;p=linux-2.6.git diff --git a/arch/x86_64/kernel/smp-xen.c b/arch/x86_64/kernel/smp-xen.c new file mode 100644 index 000000000..1b9fad1bd --- /dev/null +++ b/arch/x86_64/kernel/smp-xen.c @@ -0,0 +1,596 @@ +/* + * Intel SMP support routines. + * + * (c) 1995 Alan Cox, Building #3 + * (c) 1998-99, 2000 Ingo Molnar + * (c) 2002,2003 Andi Kleen, SuSE Labs. + * + * This code is released under the GNU General Public License version 2 or + * later. + */ + +#include + +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#ifdef CONFIG_XEN +#include +#endif + +#ifndef CONFIG_XEN +/* + * Smarter SMP flushing macros. + * c/o Linus Torvalds. + * + * These mean you can really definitely utterly forget about + * writing to user space from interrupts. (Its not allowed anyway). + * + * Optimizations Manfred Spraul + * + * More scalable flush, from Andi Kleen + * + * To avoid global state use 8 different call vectors. + * Each CPU uses a specific vector to trigger flushes on other + * CPUs. Depending on the received vector the target CPUs look into + * the right per cpu variable for the flush data. + * + * With more than 8 CPUs they are hashed to the 8 available + * vectors. The limited global vector space forces us to this right now. + * In future when interrupts are split into per CPU domains this could be + * fixed, at the cost of triggering multiple IPIs in some cases. + */ + +union smp_flush_state { + struct { + cpumask_t flush_cpumask; + struct mm_struct *flush_mm; + unsigned long flush_va; +#define FLUSH_ALL -1ULL + spinlock_t tlbstate_lock; + }; + char pad[SMP_CACHE_BYTES]; +} ____cacheline_aligned; + +/* State is put into the per CPU data section, but padded + to a full cache line because other CPUs can access it and we don't + want false sharing in the per cpu data segment. */ +static DEFINE_PER_CPU(union smp_flush_state, flush_state); +#endif + +/* + * We cannot call mmdrop() because we are in interrupt context, + * instead update mm->cpu_vm_mask. + */ +static inline void leave_mm(unsigned long cpu) +{ + if (read_pda(mmu_state) == TLBSTATE_OK) + BUG(); + cpu_clear(cpu, read_pda(active_mm)->cpu_vm_mask); + load_cr3(swapper_pg_dir); +} + +#ifndef CONFIG_XEN +/* + * + * The flush IPI assumes that a thread switch happens in this order: + * [cpu0: the cpu that switches] + * 1) switch_mm() either 1a) or 1b) + * 1a) thread switch to a different mm + * 1a1) cpu_clear(cpu, old_mm->cpu_vm_mask); + * Stop ipi delivery for the old mm. This is not synchronized with + * the other cpus, but smp_invalidate_interrupt ignore flush ipis + * for the wrong mm, and in the worst case we perform a superfluous + * tlb flush. + * 1a2) set cpu mmu_state to TLBSTATE_OK + * Now the smp_invalidate_interrupt won't call leave_mm if cpu0 + * was in lazy tlb mode. + * 1a3) update cpu active_mm + * Now cpu0 accepts tlb flushes for the new mm. + * 1a4) cpu_set(cpu, new_mm->cpu_vm_mask); + * Now the other cpus will send tlb flush ipis. + * 1a4) change cr3. + * 1b) thread switch without mm change + * cpu active_mm is correct, cpu0 already handles + * flush ipis. + * 1b1) set cpu mmu_state to TLBSTATE_OK + * 1b2) test_and_set the cpu bit in cpu_vm_mask. + * Atomically set the bit [other cpus will start sending flush ipis], + * and test the bit. + * 1b3) if the bit was 0: leave_mm was called, flush the tlb. + * 2) switch %%esp, ie current + * + * The interrupt must handle 2 special cases: + * - cr3 is changed before %%esp, ie. it cannot use current->{active_,}mm. + * - the cpu performs speculative tlb reads, i.e. even if the cpu only + * runs in kernel space, the cpu could load tlb entries for user space + * pages. + * + * The good news is that cpu mmu_state is local to each cpu, no + * write/read ordering problems. + */ + +/* + * TLB flush IPI: + * + * 1) Flush the tlb entries if the cpu uses the mm that's being flushed. + * 2) Leave the mm if we are in the lazy tlb mode. + * + * Interrupts are disabled. + */ + +asmlinkage void smp_invalidate_interrupt(struct pt_regs *regs) +{ + int cpu; + int sender; + union smp_flush_state *f; + + cpu = smp_processor_id(); + /* + * orig_rax contains the interrupt vector - 256. + * Use that to determine where the sender put the data. + */ + sender = regs->orig_rax + 256 - INVALIDATE_TLB_VECTOR_START; + f = &per_cpu(flush_state, sender); + + if (!cpu_isset(cpu, f->flush_cpumask)) + goto out; + /* + * This was a BUG() but until someone can quote me the + * line from the intel manual that guarantees an IPI to + * multiple CPUs is retried _only_ on the erroring CPUs + * its staying as a return + * + * BUG(); + */ + + if (f->flush_mm == read_pda(active_mm)) { + if (read_pda(mmu_state) == TLBSTATE_OK) { + if (f->flush_va == FLUSH_ALL) + local_flush_tlb(); + else + __flush_tlb_one(f->flush_va); + } else + leave_mm(cpu); + } +out: + ack_APIC_irq(); + cpu_clear(cpu, f->flush_cpumask); +} + +static void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm, + unsigned long va) +{ + int sender; + union smp_flush_state *f; + + /* Caller has disabled preemption */ + sender = smp_processor_id() % NUM_INVALIDATE_TLB_VECTORS; + f = &per_cpu(flush_state, sender); + + /* Could avoid this lock when + num_online_cpus() <= NUM_INVALIDATE_TLB_VECTORS, but it is + probably not worth checking this for a cache-hot lock. */ + spin_lock(&f->tlbstate_lock); + + f->flush_mm = mm; + f->flush_va = va; + cpus_or(f->flush_cpumask, cpumask, f->flush_cpumask); + + /* + * We have to send the IPI only to + * CPUs affected. + */ + send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR_START + sender); + + while (!cpus_empty(f->flush_cpumask)) + cpu_relax(); + + f->flush_mm = NULL; + f->flush_va = 0; + spin_unlock(&f->tlbstate_lock); +} + +int __cpuinit init_smp_flush(void) +{ + int i; + for_each_cpu_mask(i, cpu_possible_map) { + spin_lock_init(&per_cpu(flush_state.tlbstate_lock, i)); + } + return 0; +} + +core_initcall(init_smp_flush); + +void flush_tlb_current_task(void) +{ + struct mm_struct *mm = current->mm; + cpumask_t cpu_mask; + + preempt_disable(); + cpu_mask = mm->cpu_vm_mask; + cpu_clear(smp_processor_id(), cpu_mask); + + local_flush_tlb(); + if (!cpus_empty(cpu_mask)) + flush_tlb_others(cpu_mask, mm, FLUSH_ALL); + preempt_enable(); +} + +void flush_tlb_mm (struct mm_struct * mm) +{ + cpumask_t cpu_mask; + + preempt_disable(); + cpu_mask = mm->cpu_vm_mask; + cpu_clear(smp_processor_id(), cpu_mask); + + if (current->active_mm == mm) { + if (current->mm) + local_flush_tlb(); + else + leave_mm(smp_processor_id()); + } + if (!cpus_empty(cpu_mask)) + flush_tlb_others(cpu_mask, mm, FLUSH_ALL); + + preempt_enable(); +} + +void flush_tlb_page(struct vm_area_struct * vma, unsigned long va) +{ + struct mm_struct *mm = vma->vm_mm; + cpumask_t cpu_mask; + + preempt_disable(); + cpu_mask = mm->cpu_vm_mask; + cpu_clear(smp_processor_id(), cpu_mask); + + if (current->active_mm == mm) { + if(current->mm) + __flush_tlb_one(va); + else + leave_mm(smp_processor_id()); + } + + if (!cpus_empty(cpu_mask)) + flush_tlb_others(cpu_mask, mm, va); + + preempt_enable(); +} + +static void do_flush_tlb_all(void* info) +{ + unsigned long cpu = smp_processor_id(); + + __flush_tlb_all(); + if (read_pda(mmu_state) == TLBSTATE_LAZY) + leave_mm(cpu); +} + +void flush_tlb_all(void) +{ + on_each_cpu(do_flush_tlb_all, NULL, 1, 1); +} +#else +asmlinkage void smp_invalidate_interrupt (void) +{ return; } +void flush_tlb_current_task(void) +{ xen_tlb_flush_mask(¤t->mm->cpu_vm_mask); } +void flush_tlb_mm (struct mm_struct * mm) +{ xen_tlb_flush_mask(&mm->cpu_vm_mask); } +void flush_tlb_page(struct vm_area_struct * vma, unsigned long va) +{ xen_invlpg_mask(&vma->vm_mm->cpu_vm_mask, va); } +void flush_tlb_all(void) +{ xen_tlb_flush_all(); } +#endif /* Xen */ + +/* + * this function sends a 'reschedule' IPI to another CPU. + * it goes straight through and wastes no time serializing + * anything. Worst case is that we lose a reschedule ... + */ + +void smp_send_reschedule(int cpu) +{ + send_IPI_mask(cpumask_of_cpu(cpu), RESCHEDULE_VECTOR); +} + +/* + * Structure and data for smp_call_function(). This is designed to minimise + * static memory requirements. It also looks cleaner. + */ +static DEFINE_SPINLOCK(call_lock); + +struct call_data_struct { + void (*func) (void *info); + void *info; + atomic_t started; + atomic_t finished; + int wait; +}; + +static struct call_data_struct * call_data; + +void lock_ipi_call_lock(void) +{ + spin_lock_irq(&call_lock); +} + +void unlock_ipi_call_lock(void) +{ + spin_unlock_irq(&call_lock); +} + +/* + * this function sends a 'generic call function' IPI to one other CPU + * in the system. + * + * cpu is a standard Linux logical CPU number. + */ +static void +__smp_call_function_single(int cpu, void (*func) (void *info), void *info, + int nonatomic, int wait) +{ + struct call_data_struct data; + int cpus = 1; + + data.func = func; + data.info = info; + atomic_set(&data.started, 0); + data.wait = wait; + if (wait) + atomic_set(&data.finished, 0); + + call_data = &data; + wmb(); + /* Send a message to all other CPUs and wait for them to respond */ + send_IPI_mask(cpumask_of_cpu(cpu), CALL_FUNCTION_VECTOR); + + /* Wait for response */ + while (atomic_read(&data.started) != cpus) + cpu_relax(); + + if (!wait) + return; + + while (atomic_read(&data.finished) != cpus) + cpu_relax(); +} + +/* + * smp_call_function_single - Run a function on another CPU + * @func: The function to run. This must be fast and non-blocking. + * @info: An arbitrary pointer to pass to the function. + * @nonatomic: Currently unused. + * @wait: If true, wait until function has completed on other CPUs. + * + * Retrurns 0 on success, else a negative status code. + * + * Does not return until the remote CPU is nearly ready to execute + * or is or has executed. + */ + +int smp_call_function_single (int cpu, void (*func) (void *info), void *info, + int nonatomic, int wait) +{ + /* prevent preemption and reschedule on another processor */ + int me = get_cpu(); + if (cpu == me) { + WARN_ON(1); + put_cpu(); + return -EBUSY; + } + spin_lock_bh(&call_lock); + __smp_call_function_single(cpu, func, info, nonatomic, wait); + spin_unlock_bh(&call_lock); + put_cpu(); + return 0; +} + +/* + * this function sends a 'generic call function' IPI to all other CPUs + * in the system. + */ +static void __smp_call_function (void (*func) (void *info), void *info, + int nonatomic, int wait) +{ + struct call_data_struct data; + int cpus = num_online_cpus()-1; + + if (!cpus) + return; + + data.func = func; + data.info = info; + atomic_set(&data.started, 0); + data.wait = wait; + if (wait) + atomic_set(&data.finished, 0); + + call_data = &data; + wmb(); + /* Send a message to all other CPUs and wait for them to respond */ + send_IPI_allbutself(CALL_FUNCTION_VECTOR); + + /* Wait for response */ + while (atomic_read(&data.started) != cpus) +#ifndef CONFIG_XEN + cpu_relax(); +#else + barrier(); +#endif + + if (!wait) + return; + + while (atomic_read(&data.finished) != cpus) +#ifndef CONFIG_XEN + cpu_relax(); +#else + barrier(); +#endif +} + +/* + * smp_call_function - run a function on all other CPUs. + * @func: The function to run. This must be fast and non-blocking. + * @info: An arbitrary pointer to pass to the function. + * @nonatomic: currently unused. + * @wait: If true, wait (atomically) until function has completed on other + * CPUs. + * + * Returns 0 on success, else a negative status code. Does not return until + * remote CPUs are nearly ready to execute func or are or have executed. + * + * You must not call this function with disabled interrupts or from a + * hardware interrupt handler or from a bottom half handler. + * Actually there are a few legal cases, like panic. + */ +int smp_call_function (void (*func) (void *info), void *info, int nonatomic, + int wait) +{ + spin_lock(&call_lock); + __smp_call_function(func,info,nonatomic,wait); + spin_unlock(&call_lock); + return 0; +} + +void smp_stop_cpu(void) +{ + unsigned long flags; + /* + * Remove this CPU: + */ + cpu_clear(smp_processor_id(), cpu_online_map); + local_irq_save(flags); +#ifndef CONFIG_XEN + disable_local_APIC(); +#endif + local_irq_restore(flags); +} + +static void smp_really_stop_cpu(void *dummy) +{ + smp_stop_cpu(); + for (;;) + halt(); +} + +void smp_send_stop(void) +{ + int nolock = 0; +#ifndef CONFIG_XEN + if (reboot_force) + return; +#endif + /* Don't deadlock on the call lock in panic */ + if (!spin_trylock(&call_lock)) { + /* ignore locking because we have paniced anyways */ + nolock = 1; + } + __smp_call_function(smp_really_stop_cpu, NULL, 0, 0); + if (!nolock) + spin_unlock(&call_lock); + + local_irq_disable(); +#ifndef CONFIG_XEN + disable_local_APIC(); +#endif + local_irq_enable(); +} + +/* + * Reschedule call back. Nothing to do, + * all the work is done automatically when + * we return from the interrupt. + */ +#ifndef CONFIG_XEN +asmlinkage void smp_reschedule_interrupt(void) +#else +asmlinkage irqreturn_t smp_reschedule_interrupt(void) +#endif +{ +#ifndef CONFIG_XEN + ack_APIC_irq(); +#else + return IRQ_HANDLED; +#endif +} + +#ifndef CONFIG_XEN +asmlinkage void smp_call_function_interrupt(void) +#else +asmlinkage irqreturn_t smp_call_function_interrupt(void) +#endif +{ + void (*func) (void *info) = call_data->func; + void *info = call_data->info; + int wait = call_data->wait; + +#ifndef CONFIG_XEN + ack_APIC_irq(); +#endif + /* + * Notify initiating CPU that I've grabbed the data and am + * about to execute the function + */ + mb(); + atomic_inc(&call_data->started); + /* + * At this point the info structure may be out of scope unless wait==1 + */ + exit_idle(); + irq_enter(); + (*func)(info); + irq_exit(); + if (wait) { + mb(); + atomic_inc(&call_data->finished); + } +#ifdef CONFIG_XEN + return IRQ_HANDLED; +#endif +} + +int safe_smp_processor_id(void) +{ +#ifdef CONFIG_XEN + return smp_processor_id(); +#else + int apicid, i; + + if (disable_apic) + return 0; + + apicid = hard_smp_processor_id(); + if (x86_cpu_to_apicid[apicid] == apicid) + return apicid; + + for (i = 0; i < NR_CPUS; ++i) { + if (x86_cpu_to_apicid[i] == apicid) + return i; + } + + /* No entries in x86_cpu_to_apicid? Either no MPS|ACPI, + * or called too early. Either way, we must be CPU 0. */ + if (x86_cpu_to_apicid[0] == BAD_APICID) + return 0; + + return 0; /* Should not happen */ +#endif +}