KVM: SVM: Add support for KVM_SEV_SEND_CANCEL command

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.

Reviewed-by: Nathan Tempelman <natet@google.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Steve Rutherford <srutherford@google.com>
Message-Id: <20210412194408.2458827-1-srutherford@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
index 03f2518..c36a129 100644 (file)
--- a/Documentation/virt/kvm/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/amd-memory-encryption.rst
@@ -356,6 +356,15 @@ issued by the hypervisor to delete the encryption context.
 
 Returns: 0 on success, -negative on error
 
+14. 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 f25c52a..552f477 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1377,6 +1377,26 @@ static int sev_send_finish(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;
@@ -1448,6 +1468,9 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
        case KVM_SEV_SEND_FINISH:
                r = sev_send_finish(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/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index cb9b4c4..4172a1a 100644 (file)
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -129,6 +129,7 @@ static int sev_cmd_buffer_len(int cmd)
        case SEV_CMD_DOWNLOAD_FIRMWARE:         return sizeof(struct sev_data_download_firmware);
        case SEV_CMD_GET_ID:                    return sizeof(struct sev_data_get_id);
        case SEV_CMD_ATTESTATION_REPORT:        return sizeof(struct sev_data_attestation_report);
+       case SEV_CMD_SEND_CANCEL:                       return sizeof(struct sev_data_send_cancel);
        default:                                return 0;
        }
 

diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index 73da511..d48a719 100644 (file)
--- 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,
@@ -393,6 +394,15 @@ struct sev_data_send_finish {
 } __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
  *
  * @handle: handle of the VM to perform receive operation

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index d07be69..5d1adeb 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1674,6 +1674,8 @@ 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,
 };