[RFC PATCH 06/11] KVM: x86: Refactor common code out of sev.c
From: Ackerley Tng
Date: Mon Aug 07 2023 - 19:02:11 EST
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@xxxxxxxxxx>
Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
Co-developed-by: Vishal Annapurve <vannapurve@xxxxxxxxxx>
Signed-off-by: Vishal Annapurve <vannapurve@xxxxxxxxxx>
Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
---
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
--
2.41.0.640.ga95def55d0-goog