diff options
| -rw-r--r-- | include/linux/kvm_host.h | 1 | ||||
| -rw-r--r-- | virt/kvm/async_pf.c | 32 |
2 files changed, 18 insertions, 15 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 7e7fd25b09b3..bbfefd7e612f 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -238,7 +238,6 @@ struct kvm_async_pf { struct list_head link; struct list_head queue; struct kvm_vcpu *vcpu; - struct mm_struct *mm; gpa_t cr2_or_gpa; unsigned long addr; struct kvm_arch_async_pf arch; diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c index 85acc9e824b9..628f6df7609f 100644 --- a/virt/kvm/async_pf.c +++ b/virt/kvm/async_pf.c @@ -46,8 +46,8 @@ static void async_pf_execute(struct work_struct *work) { struct kvm_async_pf *apf = container_of(work, struct kvm_async_pf, work); - struct mm_struct *mm = apf->mm; struct kvm_vcpu *vcpu = apf->vcpu; + struct mm_struct *mm = vcpu->kvm->mm; unsigned long addr = apf->addr; gpa_t cr2_or_gpa = apf->cr2_or_gpa; int locked = 1; @@ -56,16 +56,24 @@ static void async_pf_execute(struct work_struct *work) might_sleep(); /* - * This work is run asynchronously to the task which owns - * mm and might be done in another context, so we must - * access remotely. + * Attempt to pin the VM's host address space, and simply skip gup() if + * acquiring a pin fail, i.e. if the process is exiting. Note, KVM + * holds a reference to its associated mm_struct until the very end of + * kvm_destroy_vm(), i.e. the struct itself won't be freed before this + * work item is fully processed. */ - mmap_read_lock(mm); - get_user_pages_remote(mm, addr, 1, FOLL_WRITE, NULL, &locked); - if (locked) - mmap_read_unlock(mm); - mmput(mm); + if (mmget_not_zero(mm)) { + mmap_read_lock(mm); + get_user_pages_remote(mm, addr, 1, FOLL_WRITE, NULL, &locked); + if (locked) + mmap_read_unlock(mm); + mmput(mm); + } + /* + * Notify and kick the vCPU even if faulting in the page failed, e.g. + * so that the vCPU can retry the fault synchronously. + */ if (IS_ENABLED(CONFIG_KVM_ASYNC_PF_SYNC)) kvm_arch_async_page_present(vcpu, apf); @@ -131,10 +139,8 @@ void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) #ifdef CONFIG_KVM_ASYNC_PF_SYNC flush_work(&work->work); #else - if (cancel_work_sync(&work->work)) { - mmput(work->mm); + if (cancel_work_sync(&work->work)) kmem_cache_free(async_pf_cache, work); - } #endif spin_lock(&vcpu->async_pf.lock); } @@ -205,8 +211,6 @@ bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, work->cr2_or_gpa = cr2_or_gpa; work->addr = hva; work->arch = *arch; - work->mm = current->mm; - mmget(work->mm); INIT_WORK(&work->work, async_pf_execute); |