If guest access swapped out memory do not swap it in from vcpu thread context. Setup slow work to do swapping and send async page fault to a guest.
Allow async page fault injection only when guest is in user mode since otherwise guest may be in non-sleepable context and will not be able to reschedule. Signed-off-by: Gleb Natapov <[email protected]> --- arch/x86/include/asm/kvm_host.h | 13 +++ arch/x86/kvm/Kconfig | 2 + arch/x86/kvm/mmu.c | 36 ++++++- arch/x86/kvm/paging_tmpl.h | 16 +++- arch/x86/kvm/x86.c | 37 ++++++- include/linux/kvm_host.h | 27 +++++ include/trace/events/kvm.h | 60 +++++++++++ virt/kvm/Kconfig | 3 + virt/kvm/kvm_main.c | 225 ++++++++++++++++++++++++++++++++++++++- 9 files changed, 412 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 9598e85..ad177a4 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -377,6 +377,7 @@ struct kvm_vcpu_arch { u32 __user *apf_data; u64 apf_msr_val; + u32 async_pf_id; }; struct kvm_mem_alias { @@ -539,6 +540,10 @@ struct kvm_x86_ops { const struct trace_print_flags *exit_reasons_str; }; +struct kvm_arch_async_pf { + u32 token; +}; + extern struct kvm_x86_ops *kvm_x86_ops; int kvm_mmu_module_init(void); @@ -817,4 +822,12 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v); void kvm_define_shared_msr(unsigned index, u32 msr); void kvm_set_shared_msr(unsigned index, u64 val); +struct kvm_async_pf; + +void kvm_arch_inject_async_page_not_present(struct kvm_vcpu *vcpu, + struct kvm_async_pf *work); +void kvm_arch_inject_async_page_present(struct kvm_vcpu *vcpu, + struct kvm_async_pf *work); +bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu); #endif /* _ASM_X86_KVM_HOST_H */ + diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index 4cd4983..f77b127 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -28,6 +28,8 @@ config KVM select HAVE_KVM_IRQCHIP select HAVE_KVM_EVENTFD select KVM_APIC_ARCHITECTURE + select KVM_ASYNC_PF + select SLOW_WORK select USER_RETURN_NOTIFIER ---help--- Support hosting fully virtualized guest machines using hardware diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 4c3e5b2..2cdf3e3 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -19,6 +19,7 @@ #include "mmu.h" #include "kvm_cache_regs.h" +#include "x86.h" #include <linux/kvm_host.h> #include <linux/types.h> @@ -29,6 +30,8 @@ #include <linux/swap.h> #include <linux/hugetlb.h> #include <linux/compiler.h> +#include <trace/events/kvm.h> +#undef TRACE_INCLUDE_FILE #include <asm/page.h> #include <asm/cmpxchg.h> @@ -2189,6 +2192,21 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva, error_code & PFERR_WRITE_MASK, gfn); } +int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn) +{ + struct kvm_arch_async_pf arch; + arch.token = (vcpu->arch.async_pf_id++ << 12) | vcpu->vcpu_id; + return kvm_setup_async_pf(vcpu, gva, gfn, &arch); +} + +static bool can_do_async_pf(struct kvm_vcpu *vcpu) +{ + if (!vcpu->arch.apf_data || kvm_event_needs_reinjection(vcpu)) + return false; + + return !!kvm_x86_ops->get_cpl(vcpu); +} + static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code) { @@ -2211,7 +2229,23 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, mmu_seq = vcpu->kvm->mmu_notifier_seq; smp_rmb(); - pfn = gfn_to_pfn(vcpu->kvm, gfn); + + if (can_do_async_pf(vcpu)) { + r = gfn_to_pfn_async(vcpu->kvm, gfn, &pfn); + trace_kvm_try_async_get_page(r, pfn); + } else { +do_sync: + r = 1; + pfn = gfn_to_pfn(vcpu->kvm, gfn); + } + + if (!r) { + if (!kvm_arch_setup_async_pf(vcpu, gpa, gfn)) + goto do_sync; + return 0; + } + + /* mmio */ if (is_error_pfn(pfn)) { kvm_release_pfn_clean(pfn); return 1; diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index a601713..44d19dc 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -419,7 +419,21 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, mmu_seq = vcpu->kvm->mmu_notifier_seq; smp_rmb(); - pfn = gfn_to_pfn(vcpu->kvm, walker.gfn); + + if (can_do_async_pf(vcpu)) { + r = gfn_to_pfn_async(vcpu->kvm, walker.gfn, &pfn); + trace_kvm_try_async_get_page(r, pfn); + } else { +do_sync: + r = 1; + pfn = gfn_to_pfn(vcpu->kvm, walker.gfn); + } + + if (!r) { + if (!kvm_arch_setup_async_pf(vcpu, addr, walker.gfn)) + goto do_sync; + return 0; + } /* mmio */ if (is_error_pfn(pfn)) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ce8e66d..cbbe5fd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3898,6 +3898,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) } } + kvm_check_async_pf_completion(vcpu); + preempt_disable(); kvm_x86_ops->prepare_guest_switch(vcpu); @@ -5151,8 +5153,10 @@ static void kvm_free_vcpus(struct kvm *kvm) /* * Unpin any mmu pages first. */ - kvm_for_each_vcpu(i, vcpu, kvm) + kvm_for_each_vcpu(i, vcpu, kvm) { + kvm_clear_async_pf_completion_queue(vcpu); kvm_unload_vcpu_mmu(vcpu); + } kvm_for_each_vcpu(i, vcpu, kvm) kvm_arch_vcpu_free(vcpu); @@ -5251,10 +5255,11 @@ void kvm_arch_flush_shadow(struct kvm *kvm) int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) { return vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE + || !list_empty_careful(&vcpu->async_pf_done) || vcpu->arch.mp_state == KVM_MP_STATE_SIPI_RECEIVED - || vcpu->arch.nmi_pending || - (kvm_arch_interrupt_allowed(vcpu) && - kvm_cpu_has_interrupt(vcpu)); + || vcpu->arch.nmi_pending + || (kvm_arch_interrupt_allowed(vcpu) && + kvm_cpu_has_interrupt(vcpu)); } void kvm_vcpu_kick(struct kvm_vcpu *vcpu) @@ -5301,6 +5306,30 @@ void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags) } EXPORT_SYMBOL_GPL(kvm_set_rflags); +void kvm_arch_inject_async_page_not_present(struct kvm_vcpu *vcpu, + struct kvm_async_pf *work) +{ + put_user(KVM_PV_REASON_PAGE_NOT_PRESENT, vcpu->arch.apf_data); + kvm_inject_page_fault(vcpu, work->arch.token, 0); + trace_kvm_send_async_pf(work->arch.token, work->gva, + KVM_PV_REASON_PAGE_NOT_PRESENT); +} + +void kvm_arch_inject_async_page_present(struct kvm_vcpu *vcpu, + struct kvm_async_pf *work) +{ + put_user(KVM_PV_REASON_PAGE_READY, vcpu->arch.apf_data); + kvm_inject_page_fault(vcpu, work->arch.token, 0); + trace_kvm_send_async_pf(work->arch.token, work->gva, + KVM_PV_REASON_PAGE_READY); +} + +bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu) +{ + return !kvm_event_needs_reinjection(vcpu) && + kvm_x86_ops->interrupt_allowed(vcpu); +} + EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_page_fault); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index bd5a616..7579685 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -16,6 +16,7 @@ #include <linux/mm.h> #include <linux/preempt.h> #include <linux/msi.h> +#include <linux/slow-work.h> #include <asm/signal.h> #include <linux/kvm.h> @@ -72,6 +73,25 @@ void __kvm_io_bus_unregister_dev(struct kvm_io_bus *bus, void kvm_io_bus_unregister_dev(struct kvm *kvm, struct kvm_io_bus *bus, struct kvm_io_device *dev); +#ifdef CONFIG_KVM_ASYNC_PF +struct kvm_async_pf { + struct slow_work work; + struct list_head link; + struct kvm_vcpu *vcpu; + struct mm_struct *mm; + gva_t gva; + unsigned long addr; + struct kvm_arch_async_pf arch; + struct page *page; + atomic_t used; +}; + +void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu); +void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu); +int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, + struct kvm_arch_async_pf *arch); +#endif + struct kvm_vcpu { struct kvm *kvm; #ifdef CONFIG_PREEMPT_NOTIFIERS @@ -99,6 +119,12 @@ struct kvm_vcpu { gpa_t mmio_phys_addr; #endif +#ifdef CONFIG_KVM_ASYNC_PF + struct list_head async_pf_done; + spinlock_t async_pf_lock; + struct kvm_async_pf *async_pf_work; +#endif + struct kvm_vcpu_arch arch; }; @@ -263,6 +289,7 @@ void kvm_release_page_dirty(struct page *page); void kvm_set_page_dirty(struct page *page); void kvm_set_page_accessed(struct page *page); +int gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, pfn_t *pfn); pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn); void kvm_release_pfn_dirty(pfn_t); void kvm_release_pfn_clean(pfn_t pfn); diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h index dbe1084..ddfdd8e 100644 --- a/include/trace/events/kvm.h +++ b/include/trace/events/kvm.h @@ -145,6 +145,66 @@ TRACE_EVENT(kvm_mmio, __entry->len, __entry->gpa, __entry->val) ); +#ifdef CONFIG_KVM_ASYNC_PF +TRACE_EVENT( + kvm_try_async_get_page, + TP_PROTO(bool r, u64 pfn), + TP_ARGS(r, pfn), + + TP_STRUCT__entry( + __field(__u64, pfn) + ), + + TP_fast_assign( + __entry->pfn = r ? pfn : (u64)-1; + ), + + TP_printk("pfn %#llx", __entry->pfn) +); + +TRACE_EVENT( + kvm_send_async_pf, + TP_PROTO(u64 token, u64 gva, u64 reason), + TP_ARGS(token, gva, reason), + + TP_STRUCT__entry( + __field(__u64, token) + __field(__u64, gva) + __field(bool, np) + ), + + TP_fast_assign( + __entry->token = token; + __entry->gva = gva; + __entry->np = (reason == KVM_PV_REASON_PAGE_NOT_PRESENT); + ), + + TP_printk("token %#llx gva %#llx %s", __entry->token, __entry->gva, + __entry->np ? "not present" : "ready") +); + +TRACE_EVENT( + kvm_async_pf_completed, + TP_PROTO(unsigned long address, struct page *page, u64 gva), + TP_ARGS(address, page, gva), + + TP_STRUCT__entry( + __field(unsigned long, address) + __field(struct page*, page) + __field(u64, gva) + ), + + TP_fast_assign( + __entry->address = address; + __entry->page = page; + __entry->gva = gva; + ), + + TP_printk("gva %#llx address %#lx pfn %lx", __entry->gva, + __entry->address, page_to_pfn(__entry->page)) +); +#endif + #endif /* _TRACE_KVM_MAIN_H */ /* This part must be outside protection */ diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index daece36..ccbc47a 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -12,3 +12,6 @@ config HAVE_KVM_EVENTFD config KVM_APIC_ARCHITECTURE bool + +config KVM_ASYNC_PF + bool diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index f92ba13..14ac02a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -76,6 +76,10 @@ static atomic_t hardware_enable_failed; struct kmem_cache *kvm_vcpu_cache; EXPORT_SYMBOL_GPL(kvm_vcpu_cache); +#ifdef CONFIG_KVM_ASYNC_PF +static struct kmem_cache *async_pf_cache; +#endif + static __read_mostly struct preempt_ops kvm_preempt_ops; struct dentry *kvm_debugfs_dir; @@ -176,6 +180,10 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id) vcpu->kvm = kvm; vcpu->vcpu_id = id; init_waitqueue_head(&vcpu->wq); +#ifdef CONFIG_KVM_ASYNC_PF + INIT_LIST_HEAD(&vcpu->async_pf_done); + spin_lock_init(&vcpu->async_pf_lock); +#endif page = alloc_page(GFP_KERNEL | __GFP_ZERO); if (!page) { @@ -822,6 +830,52 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn) } EXPORT_SYMBOL_GPL(gfn_to_hva); +int gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, pfn_t *pfn) +{ + struct page *page[1]; + unsigned long addr; + int npages = 0; + + *pfn = bad_pfn; + + addr = gfn_to_hva(kvm, gfn); + if (kvm_is_error_hva(addr)) { + get_page(bad_page); + return 1; + } + +#ifdef CONFIG_X86 + npages = __get_user_pages_fast(addr, 1, 1, page); + +#endif + if (unlikely(npages != 1)) { + down_read(¤t->mm->mmap_sem); + npages = get_user_pages_noio(current, current->mm, addr, 1, 1, + 0, page, NULL); + up_read(¤t->mm->mmap_sem); + } + + if (unlikely(npages != 1)) { + struct vm_area_struct *vma; + + down_read(¤t->mm->mmap_sem); + vma = find_vma(current->mm, addr); + + if (vma == NULL || addr < vma->vm_start || + !(vma->vm_flags & VM_PFNMAP)) { + up_read(¤t->mm->mmap_sem); + return 0; /* do async fault in */ + } + + *pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; + up_read(¤t->mm->mmap_sem); + BUG_ON(!kvm_is_mmio_pfn(*pfn)); + } else + *pfn = page_to_pfn(page[0]); + + return 1; +} + pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn) { struct page *page[1]; @@ -1076,6 +1130,151 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn) } } +#ifdef CONFIG_KVM_ASYNC_PF +static void async_pf_work_free(struct kvm_async_pf *apf) +{ + if (atomic_dec_and_test(&apf->used)) + kmem_cache_free(async_pf_cache, apf); +} + +static int async_pf_get_ref(struct slow_work *work) +{ + struct kvm_async_pf *apf = + container_of(work, struct kvm_async_pf, work); + + atomic_inc(&apf->used); + return 0; +} + +static void async_pf_put_ref(struct slow_work *work) +{ + struct kvm_async_pf *apf = + container_of(work, struct kvm_async_pf, work); + + kvm_put_kvm(apf->vcpu->kvm); + async_pf_work_free(apf); +} + +static void async_pf_execute(struct slow_work *work) +{ + struct page *page; + struct kvm_async_pf *apf = + container_of(work, struct kvm_async_pf, work); + wait_queue_head_t *q = &apf->vcpu->wq; + + might_sleep(); + + down_read(&apf->mm->mmap_sem); + get_user_pages(current, apf->mm, apf->addr, 1, 1, 0, &page, NULL); + up_read(&apf->mm->mmap_sem); + + spin_lock(&apf->vcpu->async_pf_lock); + list_add_tail(&apf->link, &apf->vcpu->async_pf_done); + apf->page = page; + spin_unlock(&apf->vcpu->async_pf_lock); + + trace_kvm_async_pf_completed(apf->addr, apf->page, apf->gva); + + if (waitqueue_active(q)) + wake_up_interruptible(q); + + mmdrop(apf->mm); +} + +struct slow_work_ops async_pf_ops = { + .get_ref = async_pf_get_ref, + .put_ref = async_pf_put_ref, + .execute = async_pf_execute +}; + +void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) +{ + while (!list_empty(&vcpu->async_pf_done)) { + struct kvm_async_pf *work = + list_entry(vcpu->async_pf_done.next, + typeof(*work), link); + list_del(&work->link); + put_page(work->page); + kmem_cache_free(async_pf_cache, work); + } +} + +void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu) +{ + struct kvm_async_pf *work = vcpu->async_pf_work; + + if (work) { + vcpu->async_pf_work = NULL; + if (work->page == NULL) { + kvm_arch_inject_async_page_not_present(vcpu, work); + return; + } else { + spin_lock(&vcpu->async_pf_lock); + list_del(&work->link); + spin_unlock(&vcpu->async_pf_lock); + put_page(work->page); + async_pf_work_free(work); + } + } + + if (list_empty_careful(&vcpu->async_pf_done) || + !kvm_arch_can_inject_async_page_present(vcpu)) + return; + + spin_lock(&vcpu->async_pf_lock); + work = list_first_entry(&vcpu->async_pf_done, typeof(*work), link); + list_del(&work->link); + spin_unlock(&vcpu->async_pf_lock); + + kvm_arch_inject_async_page_present(vcpu, work); + + put_page(work->page); + async_pf_work_free(work); +} + +int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, + struct kvm_arch_async_pf *arch) +{ + struct kvm_async_pf *work; + + /* setup slow work */ + + /* do alloc atomic since if we are going to sleep anyway we + may as well sleep faulting in page */ + work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC); + if (!work) + return 0; + + atomic_set(&work->used, 1); + work->page = NULL; + work->vcpu = vcpu; + work->gva = gva; + work->addr = gfn_to_hva(vcpu->kvm, gfn); + work->arch = *arch; + work->mm = current->mm; + atomic_inc(&work->mm->mm_count); + kvm_get_kvm(work->vcpu->kvm); + + /* this can't really happen otherwise gfn_to_pfn_async + would succeed */ + if (unlikely(kvm_is_error_hva(work->addr))) + goto retry_sync; + + slow_work_init(&work->work, &async_pf_ops); + if (slow_work_enqueue(&work->work) != 0) + goto retry_sync; + + vcpu->async_pf_work = work; + return 1; +retry_sync: + kvm_put_kvm(work->vcpu->kvm); + mmdrop(work->mm); + kmem_cache_free(async_pf_cache, work); + return 0; +} + +#endif + /* * The vCPU has executed a HLT instruction with in-kernel mode enabled. */ @@ -2104,6 +2303,19 @@ int kvm_init(void *opaque, unsigned int vcpu_size, goto out_free_5; } +#ifdef CONFIG_KVM_ASYNC_PF + async_pf_cache = KMEM_CACHE(kvm_async_pf, 0); + + if (!async_pf_cache) { + r = -ENOMEM; + goto out_free_6; + } + + r = slow_work_register_user(); + if (r) + goto out_free; +#endif + kvm_chardev_ops.owner = module; kvm_vm_fops.owner = module; kvm_vcpu_fops.owner = module; @@ -2111,7 +2323,7 @@ int kvm_init(void *opaque, unsigned int vcpu_size, r = misc_register(&kvm_dev); if (r) { printk(KERN_ERR "kvm: misc device register failed\n"); - goto out_free; + goto out_unreg; } kvm_preempt_ops.sched_in = kvm_sched_in; @@ -2121,7 +2333,13 @@ int kvm_init(void *opaque, unsigned int vcpu_size, return 0; +out_unreg: +#ifdef CONFIG_KVM_ASYNC_PF + slow_work_unregister_user(); out_free: + kmem_cache_destroy(async_pf_cache); +out_free_6: +#endif kmem_cache_destroy(kvm_vcpu_cache); out_free_5: sysdev_unregister(&kvm_sysdev); @@ -2150,6 +2368,11 @@ void kvm_exit(void) kvm_exit_debug(); misc_deregister(&kvm_dev); kmem_cache_destroy(kvm_vcpu_cache); +#ifdef CONFIG_KVM_ASYNC_PF + if (async_pf_cache) + kmem_cache_destroy(async_pf_cache); + slow_work_unregister_user(); +#endif sysdev_unregister(&kvm_sysdev); sysdev_class_unregister(&kvm_sysdev_class); unregister_reboot_notifier(&kvm_reboot_notifier); -- 1.6.5 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
