diff options
Diffstat (limited to 'virt/kvm/kvm_main.c')
| -rw-r--r-- | virt/kvm/kvm_main.c | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 3735212cd3f..7dd9b0b85e4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -192,6 +192,123 @@ void kvm_vcpu_uninit(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_vcpu_uninit); +#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER) +static inline struct kvm *mmu_notifier_to_kvm(struct mmu_notifier *mn) +{ + return container_of(mn, struct kvm, mmu_notifier); +} + +static void kvm_mmu_notifier_invalidate_page(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long address) +{ + struct kvm *kvm = mmu_notifier_to_kvm(mn); + int need_tlb_flush; + + /* + * When ->invalidate_page runs, the linux pte has been zapped + * already but the page is still allocated until + * ->invalidate_page returns. So if we increase the sequence + * here the kvm page fault will notice if the spte can't be + * established because the page is going to be freed. If + * instead the kvm page fault establishes the spte before + * ->invalidate_page runs, kvm_unmap_hva will release it + * before returning. + * + * The sequence increase only need to be seen at spin_unlock + * time, and not at spin_lock time. + * + * Increasing the sequence after the spin_unlock would be + * unsafe because the kvm page fault could then establish the + * pte after kvm_unmap_hva returned, without noticing the page + * is going to be freed. + */ + spin_lock(&kvm->mmu_lock); + kvm->mmu_notifier_seq++; + need_tlb_flush = kvm_unmap_hva(kvm, address); + spin_unlock(&kvm->mmu_lock); + + /* we've to flush the tlb before the pages can be freed */ + if (need_tlb_flush) + kvm_flush_remote_tlbs(kvm); + +} + +static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long start, + unsigned long end) +{ + struct kvm *kvm = mmu_notifier_to_kvm(mn); + int need_tlb_flush = 0; + + spin_lock(&kvm->mmu_lock); + /* + * The count increase must become visible at unlock time as no + * spte can be established without taking the mmu_lock and + * count is also read inside the mmu_lock critical section. + */ + kvm->mmu_notifier_count++; + for (; start < end; start += PAGE_SIZE) + need_tlb_flush |= kvm_unmap_hva(kvm, start); + spin_unlock(&kvm->mmu_lock); + + /* we've to flush the tlb before the pages can be freed */ + if (need_tlb_flush) + kvm_flush_remote_tlbs(kvm); +} + +static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long start, + unsigned long end) +{ + struct kvm *kvm = mmu_notifier_to_kvm(mn); + + spin_lock(&kvm->mmu_lock); + /* + * This sequence increase will notify the kvm page fault that + * the page that is going to be mapped in the spte could have + * been freed. + */ + kvm->mmu_notifier_seq++; + /* + * The above sequence increase must be visible before the + * below count decrease but both values are read by the kvm + * page fault under mmu_lock spinlock so we don't need to add + * a smb_wmb() here in between the two. + */ + kvm->mmu_notifier_count--; + spin_unlock(&kvm->mmu_lock); + + BUG_ON(kvm->mmu_notifier_count < 0); +} + +static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long address) +{ + struct kvm *kvm = mmu_notifier_to_kvm(mn); + int young; + + spin_lock(&kvm->mmu_lock); + young = kvm_age_hva(kvm, address); + spin_unlock(&kvm->mmu_lock); + + if (young) + kvm_flush_remote_tlbs(kvm); + + return young; +} + +static const struct mmu_notifier_ops kvm_mmu_notifier_ops = { + .invalidate_page = kvm_mmu_notifier_invalidate_page, + .invalidate_range_start = kvm_mmu_notifier_invalidate_range_start, + .invalidate_range_end = kvm_mmu_notifier_invalidate_range_end, + .clear_flush_young = kvm_mmu_notifier_clear_flush_young, +}; +#endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */ + static struct kvm *kvm_create_vm(void) { struct kvm *kvm = kvm_arch_create_vm(); @@ -212,6 +329,21 @@ static struct kvm *kvm_create_vm(void) (struct kvm_coalesced_mmio_ring *)page_address(page); #endif +#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER) + { + int err; + kvm->mmu_notifier.ops = &kvm_mmu_notifier_ops; + err = mmu_notifier_register(&kvm->mmu_notifier, current->mm); + if (err) { +#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET + put_page(page); +#endif + kfree(kvm); + return ERR_PTR(err); + } + } +#endif + kvm->mm = current->mm; atomic_inc(&kvm->mm->mm_count); spin_lock_init(&kvm->mmu_lock); @@ -272,6 +404,9 @@ static void kvm_destroy_vm(struct kvm *kvm) if (kvm->coalesced_mmio_ring != NULL) free_page((unsigned long)kvm->coalesced_mmio_ring); #endif +#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER) + mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm); +#endif kvm_arch_destroy_vm(kvm); mmdrop(mm); } |