diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/svm/sev.c | 34 | ||||
| -rw-r--r-- | arch/x86/kvm/svm/svm.h | 1 |
2 files changed, 26 insertions, 9 deletions
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 944aaea6501f..0f0ea7896af5 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -97,6 +97,8 @@ static u64 sev_supported_vmsa_features __ro_after_init; static u8 sev_enc_bit; static DECLARE_RWSEM(sev_deactivate_lock); static DEFINE_MUTEX(sev_bitmap_lock); +/* Protects kvm_sev_info's enc_context_owner, mirror_vms and mirror_entry. */ +static DEFINE_MUTEX(sev_mirror_lock); unsigned int max_sev_asid; static unsigned int min_sev_asid; static unsigned int max_sev_es_asid; @@ -2018,7 +2020,6 @@ static void sev_migrate_from(struct kvm *dst_kvm, struct kvm *src_kvm) dst->asid = src->asid; dst->handle = src->handle; dst->pages_locked = src->pages_locked; - dst->enc_context_owner = src->enc_context_owner; dst->es_active = src->es_active; dst->vmsa_features = src->vmsa_features; @@ -2026,11 +2027,12 @@ static void sev_migrate_from(struct kvm *dst_kvm, struct kvm *src_kvm) src->active = false; src->handle = 0; src->pages_locked = 0; - src->enc_context_owner = NULL; src->es_active = false; list_cut_before(&dst->regions_list, &src->regions_list, &src->regions_list); + mutex_lock(&sev_mirror_lock); + /* * If this VM has mirrors, "transfer" each mirror's refcount of the * source to the destination (this KVM). The caller holds a reference @@ -2047,12 +2049,15 @@ static void sev_migrate_from(struct kvm *dst_kvm, struct kvm *src_kvm) * If this VM is a mirror, remove the old mirror from the owners list * and add the new mirror to the list. */ - if (is_mirroring_enc_context(dst_kvm)) { - struct kvm_sev_info *owner_sev_info = to_kvm_sev_info(dst->enc_context_owner); + if (is_mirroring_enc_context(src_kvm)) { + struct kvm_sev_info *owner_sev_info = to_kvm_sev_info(src->enc_context_owner); + dst->enc_context_owner = src->enc_context_owner; + src->enc_context_owner = NULL; list_del(&src->mirror_entry); list_add_tail(&dst->mirror_entry, &owner_sev_info->mirror_vms); } + mutex_unlock(&sev_mirror_lock); kvm_for_each_vcpu(i, dst_vcpu, dst_kvm) { dst_svm = to_svm(dst_vcpu); @@ -2871,11 +2876,14 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd) * disappear until we're done with it */ source_sev = to_kvm_sev_info(source_kvm); - kvm_get_kvm(source_kvm); - list_add_tail(&mirror_sev->mirror_entry, &source_sev->mirror_vms); /* Set enc_context_owner and copy its encryption context over */ + mutex_lock(&sev_mirror_lock); + kvm_get_kvm(source_kvm); + list_add_tail(&mirror_sev->mirror_entry, &source_sev->mirror_vms); mirror_sev->enc_context_owner = source_kvm; + mutex_unlock(&sev_mirror_lock); + mirror_sev->active = true; mirror_sev->asid = source_sev->asid; mirror_sev->fd = source_sev->fd; @@ -2963,11 +2971,19 @@ void sev_vm_destroy(struct kvm *kvm) * Note, mirror VMs don't support registering encrypted regions. */ if (is_mirroring_enc_context(kvm)) { - struct kvm *owner_kvm = sev->enc_context_owner; + struct kvm *owner_kvm; - mutex_lock(&owner_kvm->lock); + mutex_lock(&sev_mirror_lock); + owner_kvm = sev->enc_context_owner; list_del(&sev->mirror_entry); - mutex_unlock(&owner_kvm->lock); + sev->enc_context_owner = NULL; + + /* + * The reference to owner_kvm cannot move after sev_mirror_lock is + * released. Release it before kvm_put_kvm() so that owner_kvm is + * never destroyed inside sev_mirror_lock. + */ + mutex_unlock(&sev_mirror_lock); kvm_put_kvm(owner_kvm); return; } diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 716be21fba33..d63e5878988a 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -109,6 +109,7 @@ struct kvm_sev_info { u64 ap_jump_table; /* SEV-ES AP Jump Table address */ u64 vmsa_features; u16 ghcb_version; /* Highest guest GHCB protocol version allowed */ + /* The three fields below are protected by sev_mirror_lock */ struct kvm *enc_context_owner; /* Owner of copied encryption context */ struct list_head mirror_vms; /* List of VMs mirroring */ struct list_head mirror_entry; /* Use as a list entry of mirrors */ |