Split sev_lock_two_vms() into kvm_mark_migration_in_progress() and kvm_lock_two_vms() and refactor sev.c to use these two new functions.
Co-developed-by: Sagi Shahar sagis@google.com Signed-off-by: Sagi Shahar sagis@google.com Co-developed-by: Vishal Annapurve vannapurve@google.com Signed-off-by: Vishal Annapurve vannapurve@google.com Signed-off-by: Ackerley Tng ackerleytng@google.com --- arch/x86/kvm/svm/sev.c | 59 ++++++++++------------------------------ arch/x86/kvm/x86.c | 62 ++++++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/x86.h | 6 ++++ 3 files changed, 82 insertions(+), 45 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 725289b523c7..3c4313417966 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -1554,47 +1554,6 @@ static bool is_cmd_allowed_from_mirror(u32 cmd_id) return false; }
-static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) -{ - int r = -EBUSY; - - if (dst_kvm == src_kvm) - return -EINVAL; - - /* - * 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(&dst_kvm->migration_in_progress, 0, 1)) - return -EBUSY; - - if (atomic_cmpxchg_acquire(&src_kvm->migration_in_progress, 0, 1)) - goto release_dst; - - r = -EINTR; - if (mutex_lock_killable(&dst_kvm->lock)) - goto release_src; - if (mutex_lock_killable_nested(&src_kvm->lock, SINGLE_DEPTH_NESTING)) - goto unlock_dst; - return 0; - -unlock_dst: - mutex_unlock(&dst_kvm->lock); -release_src: - atomic_set_release(&src_kvm->migration_in_progress, 0); -release_dst: - atomic_set_release(&dst_kvm->migration_in_progress, 0); - return r; -} - -static void sev_unlock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) -{ - mutex_unlock(&dst_kvm->lock); - mutex_unlock(&src_kvm->lock); - atomic_set_release(&dst_kvm->migration_in_progress, 0); - atomic_set_release(&src_kvm->migration_in_progress, 0); -} - /* vCPU mutex subclasses. */ enum sev_migration_role { SEV_MIGRATION_SOURCE = 0, @@ -1777,9 +1736,12 @@ int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd) }
source_kvm = f.file->private_data; - ret = sev_lock_two_vms(kvm, source_kvm); + ret = kvm_mark_migration_in_progress(kvm, source_kvm); if (ret) goto out_fput; + ret = kvm_lock_two_vms(kvm, source_kvm); + if (ret) + goto out_mark_migration_done;
if (sev_guest(kvm) || !sev_guest(source_kvm)) { ret = -EINVAL; @@ -1823,8 +1785,10 @@ int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd) sev_misc_cg_uncharge(cg_cleanup_sev); put_misc_cg(cg_cleanup_sev->misc_cg); cg_cleanup_sev->misc_cg = NULL; +out_mark_migration_done: + kvm_mark_migration_done(kvm, source_kvm); out_unlock: - sev_unlock_two_vms(kvm, source_kvm); + kvm_unlock_two_vms(kvm, source_kvm); out_fput: fdput(f); return ret; @@ -2057,9 +2021,12 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd) }
source_kvm = f.file->private_data; - ret = sev_lock_two_vms(kvm, source_kvm); + ret = kvm_mark_migration_in_progress(kvm, source_kvm); if (ret) goto e_source_fput; + ret = kvm_lock_two_vms(kvm, source_kvm); + if (ret) + goto e_mark_migration_done;
/* * Mirrors of mirrors should work, but let's not get silly. Also @@ -2100,7 +2067,9 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd) */
e_unlock: - sev_unlock_two_vms(kvm, source_kvm); + kvm_unlock_two_vms(kvm, source_kvm); +e_mark_migration_done: + kvm_mark_migration_done(kvm, source_kvm); e_source_fput: fdput(f); return ret; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index de195ad83ec0..494b75ef7197 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4340,6 +4340,68 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) } EXPORT_SYMBOL_GPL(kvm_get_msr_common);
+int kvm_mark_migration_in_progress(struct kvm *dst_kvm, struct kvm *src_kvm) +{ + int r; + + if (dst_kvm == src_kvm) + return -EINVAL; + + /* + * Bail if these VMs are already involved in a migration to avoid + * deadlock between two VMs trying to migrate to/from each other. + */ + r = -EBUSY; + if (atomic_cmpxchg_acquire(&dst_kvm->migration_in_progress, 0, 1)) + return r; + + if (atomic_cmpxchg_acquire(&src_kvm->migration_in_progress, 0, 1)) + goto release_dst; + + return 0; + +release_dst: + atomic_set_release(&dst_kvm->migration_in_progress, 0); + return r; +} +EXPORT_SYMBOL_GPL(kvm_mark_migration_in_progress); + +void kvm_mark_migration_done(struct kvm *dst_kvm, struct kvm *src_kvm) +{ + atomic_set_release(&dst_kvm->migration_in_progress, 0); + atomic_set_release(&src_kvm->migration_in_progress, 0); +} +EXPORT_SYMBOL_GPL(kvm_mark_migration_done); + +int kvm_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) +{ + int r; + + if (dst_kvm == src_kvm) + return -EINVAL; + + r = -EINTR; + if (mutex_lock_killable(&dst_kvm->lock)) + return r; + + if (mutex_lock_killable_nested(&src_kvm->lock, SINGLE_DEPTH_NESTING)) + goto unlock_dst; + + return 0; + +unlock_dst: + mutex_unlock(&dst_kvm->lock); + return r; +} +EXPORT_SYMBOL_GPL(kvm_lock_two_vms); + +void kvm_unlock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) +{ + mutex_unlock(&dst_kvm->lock); + mutex_unlock(&src_kvm->lock); +} +EXPORT_SYMBOL_GPL(kvm_unlock_two_vms); + /* * Read or write a bunch of msrs. All parameters are kernel addresses. * diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 82e3dafc5453..4c6edaf5ac5b 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -539,4 +539,10 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size, unsigned int port, void *data, unsigned int count, int in);
+int kvm_mark_migration_in_progress(struct kvm *dst_kvm, struct kvm *src_kvm); +void kvm_mark_migration_done(struct kvm *dst_kvm, struct kvm *src_kvm); + +int kvm_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm); +void kvm_unlock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm); + #endif