From: Paolo Bonzini Date: Fri, 12 Nov 2021 04:02:24 -0500 Subject: KVM: SEV: unify cgroup cleanup code for svm_vm_migrate_from Git-commit: 501cfe06790651af4470d8ca77f162515867cd4d Patch-mainline: v5.16-rc1 References: jsc#SLE-19924 Use the same cleanup code independent of whether the cgroup to be uncharged and unref'd is the source or the destination cgroup. Use a bool to track whether the destination cgroup has been charged, which also fixes a bug in the error case: the destination cgroup must be uncharged only if it does not match the source. Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration") Signed-off-by: Paolo Bonzini Acked-by: Joerg Roedel --- arch/x86/kvm/svm/sev.c | 25 +++++++++++-------------- 1 file changed, 11 insertions(+), 14 deletions(-) --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -1615,12 +1615,6 @@ static void sev_migrate_from(struct kvm_ src->handle = 0; src->pages_locked = 0; - if (dst->misc_cg != src->misc_cg) - sev_misc_cg_uncharge(src); - - put_misc_cg(src->misc_cg); - src->misc_cg = NULL; - INIT_LIST_HEAD(&dst->regions_list); list_replace_init(&src->regions_list, &dst->regions_list); } @@ -1668,9 +1662,10 @@ static int sev_es_migrate_from(struct kv int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd) { struct kvm_sev_info *dst_sev = &to_kvm_svm(kvm)->sev_info; - struct kvm_sev_info *src_sev; + struct kvm_sev_info *src_sev, *cg_cleanup_sev; struct file *source_kvm_file; struct kvm *source_kvm; + bool charged = false; int ret; ret = sev_lock_for_migration(kvm); @@ -1700,10 +1695,12 @@ int svm_vm_migrate_from(struct kvm *kvm, src_sev = &to_kvm_svm(source_kvm)->sev_info; dst_sev->misc_cg = get_current_misc_cg(); + cg_cleanup_sev = dst_sev; if (dst_sev->misc_cg != src_sev->misc_cg) { ret = sev_misc_cg_try_charge(dst_sev); if (ret) - goto out_dst_put_cgroup; + goto out_dst_cgroup; + charged = true; } ret = sev_lock_vcpus_for_migration(kvm); @@ -1720,6 +1717,7 @@ int svm_vm_migrate_from(struct kvm *kvm, } sev_migrate_from(dst_sev, src_sev); kvm_vm_dead(source_kvm); + cg_cleanup_sev = src_sev; ret = 0; out_source_vcpu: @@ -1727,12 +1725,11 @@ out_source_vcpu: out_dst_vcpu: sev_unlock_vcpus_for_migration(kvm); out_dst_cgroup: - if (ret < 0) { - sev_misc_cg_uncharge(dst_sev); -out_dst_put_cgroup: - put_misc_cg(dst_sev->misc_cg); - dst_sev->misc_cg = NULL; - } + /* Operates on the source on success, on the destination on failure. */ + if (charged) + 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_fput: