From 501b580c02339a83917cf3b44c445f2419b15dcb Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 22 Nov 2021 19:50:29 -0500 Subject: KVM: SEV: cleanup locking for KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM Encapsulate the handling of the migration_in_progress flag for both VMs in two functions sev_lock_two_vms and sev_unlock_two_vms. It does not matter if KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM locks the destination struct kvm a bit later, and this change 1) keeps the cleanup chain of labels smaller 2) makes it possible for KVM_CAP_VM_COPY_ENC_CONTEXT_FROM to reuse the logic. Cc: Peter Gonda Cc: Sean Christopherson Message-Id: <20211123005036.2954379-6-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 53 +++++++++++++++++++++++++------------------------- 1 file changed, 27 insertions(+), 26 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 75955beb3770..8902b018fc18 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -1543,28 +1543,40 @@ static bool is_cmd_allowed_from_mirror(u32 cmd_id) return false; } -static int sev_lock_for_migration(struct kvm *kvm) +static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) { - struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + struct kvm_sev_info *dst_sev = &to_kvm_svm(dst_kvm)->sev_info; + struct kvm_sev_info *src_sev = &to_kvm_svm(src_kvm)->sev_info; + + if (dst_kvm == src_kvm) + return -EINVAL; /* - * Bail if this VM is already involved in a migration to avoid deadlock - * between two VMs trying to migrate to/from each other. + * Bail if these VMs are already involved in a migration to avoid + * deadlock between two VMs trying to migrate to/from each other. */ - if (atomic_cmpxchg_acquire(&sev->migration_in_progress, 0, 1)) + if (atomic_cmpxchg_acquire(&dst_sev->migration_in_progress, 0, 1)) return -EBUSY; - mutex_lock(&kvm->lock); + if (atomic_cmpxchg_acquire(&src_sev->migration_in_progress, 0, 1)) { + atomic_set_release(&dst_sev->migration_in_progress, 0); + return -EBUSY; + } + mutex_lock(&dst_kvm->lock); + mutex_lock(&src_kvm->lock); return 0; } -static void sev_unlock_after_migration(struct kvm *kvm) +static void sev_unlock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) { - struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + struct kvm_sev_info *dst_sev = &to_kvm_svm(dst_kvm)->sev_info; + struct kvm_sev_info *src_sev = &to_kvm_svm(src_kvm)->sev_info; - mutex_unlock(&kvm->lock); - atomic_set_release(&sev->migration_in_progress, 0); + mutex_unlock(&dst_kvm->lock); + mutex_unlock(&src_kvm->lock); + atomic_set_release(&dst_sev->migration_in_progress, 0); + atomic_set_release(&src_sev->migration_in_progress, 0); } @@ -1665,15 +1677,6 @@ int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd) bool charged = false; int ret; - ret = sev_lock_for_migration(kvm); - if (ret) - return ret; - - if (sev_guest(kvm)) { - ret = -EINVAL; - goto out_unlock; - } - source_kvm_file = fget(source_fd); if (!file_is_kvm(source_kvm_file)) { ret = -EBADF; @@ -1681,13 +1684,13 @@ int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd) } source_kvm = source_kvm_file->private_data; - ret = sev_lock_for_migration(source_kvm); + ret = sev_lock_two_vms(kvm, source_kvm); if (ret) goto out_fput; - if (!sev_guest(source_kvm)) { + if (sev_guest(kvm) || !sev_guest(source_kvm)) { ret = -EINVAL; - goto out_source; + goto out_unlock; } src_sev = &to_kvm_svm(source_kvm)->sev_info; @@ -1727,13 +1730,11 @@ out_dst_cgroup: sev_misc_cg_uncharge(cg_cleanup_sev); put_misc_cg(cg_cleanup_sev->misc_cg); cg_cleanup_sev->misc_cg = NULL; -out_source: - sev_unlock_after_migration(source_kvm); +out_unlock: + sev_unlock_two_vms(kvm, source_kvm); out_fput: if (source_kvm_file) fput(source_kvm_file); -out_unlock: - sev_unlock_after_migration(kvm); return ret; } -- cgit