KVM: SVM: Add support for KVM_SEV_RECEIVE_START command

The command is used to create the encryption context for an incoming
SEV guest. The encryption context can be later used by the hypervisor
to import the incoming data into the SEV guest memory space.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Steve Rutherford <srutherford@google.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Message-Id: <c7400111ed7458eee01007c4d8d57cdf2cbb0fc2.1618498113.git.ashish.kalra@amd.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 c36a12975763ee8f6d244607d4983e0480ad6cbc..86c9b36f4a57c38fa42fb6f978abc6525c6545f3 100644 (file)
--- a/Documentation/virt/kvm/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/amd-memory-encryption.rst
@@ -365,6 +365,35 @@ migration can restart with a new target later.
 
 Returns: 0 on success, -negative on error
 
+15. KVM_SEV_RECEIVE_START
+------------------------
+
+The KVM_SEV_RECEIVE_START command is used for creating the memory encryption
+context for an incoming SEV guest. To create the encryption context, the user must
+provide a guest policy, the platform public Diffie-Hellman (PDH) key and session
+information.
+
+Parameters: struct  kvm_sev_receive_start (in/out)
+
+Returns: 0 on success, -negative on error
+
+::
+
+        struct kvm_sev_receive_start {
+                __u32 handle;           /* if zero then firmware creates a new handle */
+                __u32 policy;           /* guest's policy */
+
+                __u64 pdh_uaddr;        /* userspace address pointing to the PDH key */
+                __u32 pdh_len;
+
+                __u64 session_uaddr;    /* userspace address which points to the guest session information */
+                __u32 session_len;
+        };
+
+On success, the 'handle' field contains a new handle and on error, a negative value.
+
+For more details, see SEV spec Section 6.12.
+
 References
 ==========
 

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 552f477871434239d8da26b694fb4d8059996d48..3e5064c691244a8e9ecccdeb9f9459c69f701538 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1397,6 +1397,84 @@ static int sev_send_cancel(struct kvm *kvm, struct kvm_sev_cmd *argp)
        return ret;
 }
 
+static int sev_receive_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+       struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+       struct sev_data_receive_start *start;
+       struct kvm_sev_receive_start params;
+       int *error = &argp->error;
+       void *session_data;
+       void *pdh_data;
+       int ret;
+
+       if (!sev_guest(kvm))
+               return -ENOTTY;
+
+       /* Get parameter from the userspace */
+       if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
+                       sizeof(struct kvm_sev_receive_start)))
+               return -EFAULT;
+
+       /* some sanity checks */
+       if (!params.pdh_uaddr || !params.pdh_len ||
+           !params.session_uaddr || !params.session_len)
+               return -EINVAL;
+
+       pdh_data = psp_copy_user_blob(params.pdh_uaddr, params.pdh_len);
+       if (IS_ERR(pdh_data))
+               return PTR_ERR(pdh_data);
+
+       session_data = psp_copy_user_blob(params.session_uaddr,
+                       params.session_len);
+       if (IS_ERR(session_data)) {
+               ret = PTR_ERR(session_data);
+               goto e_free_pdh;
+       }
+
+       ret = -ENOMEM;
+       start = kzalloc(sizeof(*start), GFP_KERNEL);
+       if (!start)
+               goto e_free_session;
+
+       start->handle = params.handle;
+       start->policy = params.policy;
+       start->pdh_cert_address = __psp_pa(pdh_data);
+       start->pdh_cert_len = params.pdh_len;
+       start->session_address = __psp_pa(session_data);
+       start->session_len = params.session_len;
+
+       /* create memory encryption context */
+       ret = __sev_issue_cmd(argp->sev_fd, SEV_CMD_RECEIVE_START, start,
+                               error);
+       if (ret)
+               goto e_free;
+
+       /* Bind ASID to this guest */
+       ret = sev_bind_asid(kvm, start->handle, error);
+       if (ret)
+               goto e_free;
+
+       params.handle = start->handle;
+       if (copy_to_user((void __user *)(uintptr_t)argp->data,
+                        &params, sizeof(struct kvm_sev_receive_start))) {
+               ret = -EFAULT;
+               sev_unbind_asid(kvm, start->handle);
+               goto e_free;
+       }
+
+       sev->handle = start->handle;
+       sev->fd = argp->sev_fd;
+
+e_free:
+       kfree(start);
+e_free_session:
+       kfree(session_data);
+e_free_pdh:
+       kfree(pdh_data);
+
+       return ret;
+}
+
 int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 {
        struct kvm_sev_cmd sev_cmd;
@@ -1471,6 +1549,9 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
        case KVM_SEV_SEND_CANCEL:
                r = sev_send_cancel(kvm, &sev_cmd);
                break;
+       case KVM_SEV_RECEIVE_START:
+               r = sev_receive_start(kvm, &sev_cmd);
+               break;
        default:
                r = -EINVAL;
                goto out;

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 5d1adeb13739f294492314d5119214c3e0c18f33..248d1d266bc3a7be62e8eee6fc6e9111a67e8490 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1755,6 +1755,15 @@ struct kvm_sev_send_update_data {
        __u32 trans_len;
 };
 
+struct kvm_sev_receive_start {
+       __u32 handle;
+       __u32 policy;
+       __u64 pdh_uaddr;
+       __u32 pdh_len;
+       __u64 session_uaddr;
+       __u32 session_len;
+};
+
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU    (1 << 0)
 #define KVM_DEV_ASSIGN_PCI_2_3         (1 << 1)
 #define KVM_DEV_ASSIGN_MASK_INTX       (1 << 2)