From: Keith Busch <kbusch@xxxxxxxxxx> Some libraries ensure they are single threaded before forking. This assumption breaks after making kvm hugepage recovery thread a vhost task of the user process. The minijail library used by crosvm is one such affected application. Defer the task to after the first VM_RUN call, which occurs after the parent process has forked all its jailed child processes and should be safe to start the vhost task. Link: https://lore.kernel.org/kvm/Z2RYyagu3phDFIac@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ Fixes: d96c77bd4eeba46 ("KVM: x86: switch hugepage recovery thread to vhost_task") Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx> --- arch/x86/kvm/mmu/mmu.c | 2 ++ arch/x86/kvm/x86.c | 9 ++++----- include/linux/kvm_host.h | 1 - virt/kvm/kvm_main.c | 15 --------------- 4 files changed, 6 insertions(+), 21 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 2401606db2604..422b6b06de4fe 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -7415,6 +7415,8 @@ int kvm_mmu_post_init_vm(struct kvm *kvm) { if (nx_hugepage_mitigation_hard_disabled) return 0; + if (kvm->arch.nx_huge_page_recovery_thread) + return 0; kvm->arch.nx_huge_page_last = get_jiffies_64(); kvm->arch.nx_huge_page_recovery_thread = vhost_task_create( diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c79a8cc57ba42..263363c46626b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11463,6 +11463,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) struct kvm_run *kvm_run = vcpu->run; int r; + r = kvm_mmu_post_init_vm(vcpu->kvm); + if (r) + return r; + vcpu_load(vcpu); kvm_sigset_activate(vcpu); kvm_run->flags = 0; @@ -12740,11 +12744,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) return ret; } -int kvm_arch_post_init_vm(struct kvm *kvm) -{ - return kvm_mmu_post_init_vm(kvm); -} - static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu) { vcpu_load(vcpu); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 401439bb21e3e..a219bd2d8aec8 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1596,7 +1596,6 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu); bool kvm_arch_dy_runnable(struct kvm_vcpu *vcpu); bool kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu); bool kvm_arch_vcpu_preempted_in_kernel(struct kvm_vcpu *vcpu); -int kvm_arch_post_init_vm(struct kvm *kvm); void kvm_arch_pre_destroy_vm(struct kvm *kvm); void kvm_arch_create_vm_debugfs(struct kvm *kvm); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index de2c11dae2316..adacc6eaa7d9d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1065,15 +1065,6 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname) return ret; } -/* - * Called after the VM is otherwise initialized, but just before adding it to - * the vm_list. - */ -int __weak kvm_arch_post_init_vm(struct kvm *kvm) -{ - return 0; -} - /* * Called just after removing the VM from the vm_list, but before doing any * other destruction. @@ -1194,10 +1185,6 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname) if (r) goto out_err_no_debugfs; - r = kvm_arch_post_init_vm(kvm); - if (r) - goto out_err; - mutex_lock(&kvm_lock); list_add(&kvm->vm_list, &vm_list); mutex_unlock(&kvm_lock); @@ -1207,8 +1194,6 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname) return kvm; -out_err: - kvm_destroy_vm_debugfs(kvm); out_err_no_debugfs: kvm_coalesced_mmio_free(kvm); out_no_coalesced_mmio: -- 2.43.5
