After completion of SEND_START, but before SEND_FINISH, the source VMM can
issue the SEND_CANCEL command to stop a migration. This is necessary so
that a cancelled migration can restart with a new target later.

Signed-off-by: Steve Rutherford <srutherf...@google.com>
---
 .../virt/kvm/amd-memory-encryption.rst        |  9 +++++++
 arch/x86/kvm/svm/sev.c                        | 24 +++++++++++++++++++
 include/linux/psp-sev.h                       | 10 ++++++++
 include/uapi/linux/kvm.h                      |  2 ++
 4 files changed, 45 insertions(+)

diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst 
b/Documentation/virt/kvm/amd-memory-encryption.rst
index 469a6308765b1..9e018a3eec03b 100644
--- a/Documentation/virt/kvm/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/amd-memory-encryption.rst
@@ -284,6 +284,15 @@ Returns: 0 on success, -negative on error
                 __u32 len;
         };
 
+16. KVM_SEV_SEND_CANCEL
+------------------------
+
+After completion of SEND_START, but before SEND_FINISH, the source VMM can 
issue the
+SEND_CANCEL command to stop a migration. This is necessary so that a cancelled
+migration can restart with a new target later.
+
+Returns: 0 on success, -negative on error
+
 References
 ==========
 
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 83e00e5245136..88e72102cb900 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1110,6 +1110,27 @@ static int sev_get_attestation_report(struct kvm *kvm, 
struct kvm_sev_cmd *argp)
        return ret;
 }
 
+static int sev_send_cancel(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+       struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+       struct sev_data_send_cancel *data;
+       int ret;
+
+       if (!sev_guest(kvm))
+               return -ENOTTY;
+
+       data = kzalloc(sizeof(*data), GFP_KERNEL);
+       if (!data)
+               return -ENOMEM;
+
+       data->handle = sev->handle;
+       ret = sev_issue_cmd(kvm, SEV_CMD_SEND_CANCEL, data, &argp->error);
+
+       kfree(data);
+       return ret;
+}
+
+
 int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 {
        struct kvm_sev_cmd sev_cmd;
@@ -1163,6 +1184,9 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
        case KVM_SEV_GET_ATTESTATION_REPORT:
                r = sev_get_attestation_report(kvm, &sev_cmd);
                break;
+       case KVM_SEV_SEND_CANCEL:
+               r = sev_send_cancel(kvm, &sev_cmd);
+               break;
        default:
                r = -EINVAL;
                goto out;
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index b801ead1e2bb5..74f2babffc574 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -73,6 +73,7 @@ enum sev_cmd {
        SEV_CMD_SEND_UPDATE_DATA        = 0x041,
        SEV_CMD_SEND_UPDATE_VMSA        = 0x042,
        SEV_CMD_SEND_FINISH             = 0x043,
+       SEV_CMD_SEND_CANCEL             = 0x044,
 
        /* Guest migration commands (incoming) */
        SEV_CMD_RECEIVE_START           = 0x050,
@@ -392,6 +393,15 @@ struct sev_data_send_finish {
        u32 handle;                             /* In */
 } __packed;
 
+/**
+ * struct sev_data_send_cancel - SEND_CANCEL command parameters
+ *
+ * @handle: handle of the VM to process
+ */
+struct sev_data_send_cancel {
+       u32 handle;                             /* In */
+} __packed;
+
 /**
  * struct sev_data_receive_start - RECEIVE_START command parameters
  *
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index f6afee209620d..707469b6b7072 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1671,6 +1671,8 @@ enum sev_cmd_id {
        KVM_SEV_CERT_EXPORT,
        /* Attestation report */
        KVM_SEV_GET_ATTESTATION_REPORT,
+       /* Guest Migration Extension */
+       KVM_SEV_SEND_CANCEL,
 
        KVM_SEV_NR_MAX,
 };
-- 
2.31.0.208.g409f899ff0-goog

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