From bf42b02b19e27d6849852a41dd734af4c05e73c6 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 22 Nov 2021 19:50:33 -0500 Subject: KVM: SEV: Do COPY_ENC_CONTEXT_FROM with both VMs locked Now that we have a facility to lock two VMs with deadlock protection, use it for the creation of mirror VMs as well. One of COPY_ENC_CONTEXT_FROM(dst, src) and COPY_ENC_CONTEXT_FROM(src, dst) would always fail, so the combination is nonsensical and it is okay to return -EBUSY if it is attempted. This sidesteps the question of what happens if a VM is MOVE_ENC_CONTEXT_FROM'd at the same time as it is COPY_ENC_CONTEXT_FROM'd: the locking prevents that from happening. Cc: Peter Gonda Cc: Sean Christopherson Reviewed-by: Sean Christopherson Message-Id: <20211123005036.2954379-10-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 66 ++++++++++++++++++-------------------------------- 1 file changed, 24 insertions(+), 42 deletions(-) (limited to 'arch') diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 74b6459b5fb2..025d9731b66c 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -1955,77 +1955,59 @@ int svm_vm_copy_asid_from(struct kvm *kvm, unsigned int source_fd) { struct file *source_kvm_file; struct kvm *source_kvm; - struct kvm_sev_info source_sev, *mirror_sev; + struct kvm_sev_info *source_sev, *mirror_sev; int ret; source_kvm_file = fget(source_fd); if (!file_is_kvm(source_kvm_file)) { ret = -EBADF; - goto e_source_put; + goto e_source_fput; } source_kvm = source_kvm_file->private_data; - mutex_lock(&source_kvm->lock); - - if (!sev_guest(source_kvm)) { - ret = -EINVAL; - goto e_source_unlock; - } + ret = sev_lock_two_vms(kvm, source_kvm); + if (ret) + goto e_source_fput; - /* Mirrors of mirrors should work, but let's not get silly */ - if (is_mirroring_enc_context(source_kvm) || source_kvm == kvm) { + /* + * Mirrors of mirrors should work, but let's not get silly. Also + * disallow out-of-band SEV/SEV-ES init if the target is already an + * SEV guest, or if vCPUs have been created. KVM relies on vCPUs being + * created after SEV/SEV-ES initialization, e.g. to init intercepts. + */ + if (sev_guest(kvm) || !sev_guest(source_kvm) || + is_mirroring_enc_context(source_kvm) || kvm->created_vcpus) { ret = -EINVAL; - goto e_source_unlock; + goto e_unlock; } - memcpy(&source_sev, &to_kvm_svm(source_kvm)->sev_info, - sizeof(source_sev)); - /* * The mirror kvm holds an enc_context_owner ref so its asid can't * disappear until we're done with it */ + source_sev = &to_kvm_svm(source_kvm)->sev_info; kvm_get_kvm(source_kvm); - fput(source_kvm_file); - mutex_unlock(&source_kvm->lock); - mutex_lock(&kvm->lock); - - /* - * Disallow out-of-band SEV/SEV-ES init if the target is already an - * SEV guest, or if vCPUs have been created. KVM relies on vCPUs being - * created after SEV/SEV-ES initialization, e.g. to init intercepts. - */ - if (sev_guest(kvm) || kvm->created_vcpus) { - ret = -EINVAL; - goto e_mirror_unlock; - } - /* Set enc_context_owner and copy its encryption context over */ mirror_sev = &to_kvm_svm(kvm)->sev_info; mirror_sev->enc_context_owner = source_kvm; mirror_sev->active = true; - mirror_sev->asid = source_sev.asid; - mirror_sev->fd = source_sev.fd; - mirror_sev->es_active = source_sev.es_active; - mirror_sev->handle = source_sev.handle; + mirror_sev->asid = source_sev->asid; + mirror_sev->fd = source_sev->fd; + mirror_sev->es_active = source_sev->es_active; + mirror_sev->handle = source_sev->handle; INIT_LIST_HEAD(&mirror_sev->regions_list); + ret = 0; + /* * Do not copy ap_jump_table. Since the mirror does not share the same * KVM contexts as the original, and they may have different * memory-views. */ - mutex_unlock(&kvm->lock); - return 0; - -e_mirror_unlock: - mutex_unlock(&kvm->lock); - kvm_put_kvm(source_kvm); - return ret; -e_source_unlock: - mutex_unlock(&source_kvm->lock); -e_source_put: +e_unlock: + sev_unlock_two_vms(kvm, source_kvm); +e_source_fput: if (source_kvm_file) fput(source_kvm_file); return ret; -- cgit v1.2.3