[PATCH Part2 v5 27/45] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command

Brijesh Singh
2021-08-20T16:00:31Z

The KVM_SEV_SNP_LAUNCH_FINISH finalize the cryptographic digest and stores
it as the measurement of the guest at launch.

While finalizing the launch flow, it also issues the LAUNCH_UPDATE command
to encrypt the VMSA pages.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
.../virt/kvm/amd-memory-encryption.rst | 22 ++++
arch/x86/kvm/svm/sev.c | 116 ++++++++++++++++++
include/uapi/linux/kvm.h | 14 +++
3 files changed, 152 insertions(+)

diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
index ddcd94e9ffed..c7332e0e0baa 100644
--- a/Documentation/virt/kvm/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/amd-memory-encryption.rst
@@ -506,6 +506,28 @@ Returns: 0 on success, -negative on error
See the SEV-SNP spec for further details on how to build the VMPL permission
mask and page type.

+21. KVM_SNP_LAUNCH_FINISH
+-------------------------
+
+After completion of the SNP guest launch flow, the KVM_SNP_LAUNCH_FINISH command can be
+issued to make the guest ready for the execution.
+
+Parameters (in): struct kvm_sev_snp_launch_finish
+
+Returns: 0 on success, -negative on error
+
+::
+
+ struct kvm_sev_snp_launch_finish {
+ __u64 id_block_uaddr;
+ __u64 id_auth_uaddr;
+ __u8 id_block_en;
+ __u8 auth_key_en;
+ __u8 host_data[32];
+ };
+
+
+See SEV-SNP specification for further details on launch finish input parameters.

References
==========
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index dcef0ae5f8e4..248096a5c307 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1813,6 +1813,106 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp)
return ret;
}

+static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+ struct sev_data_snp_launch_update data = {};
+ int i, ret;
+
+ data.gctx_paddr = __psp_pa(sev->snp_context);
+ data.page_type = SNP_PAGE_TYPE_VMSA;
+
+ for (i = 0; i < kvm->created_vcpus; i++) {
+ struct vcpu_svm *svm = to_svm(kvm->vcpus[i]);
+ u64 pfn = __pa(svm->vmsa) >> PAGE_SHIFT;
+
+ /* Perform some pre-encryption checks against the VMSA */
+ ret = sev_es_sync_vmsa(svm);
+ if (ret)
+ return ret;
+
+ /* Transition the VMSA page to a firmware state. */
+ ret = rmp_make_private(pfn, -1, PG_LEVEL_4K, sev->asid, true);
+ if (ret)
+ return ret;
+
+ /* Issue the SNP command to encrypt the VMSA */
+ data.address = __sme_pa(svm->vmsa);
+ ret = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_UPDATE,
+ &data, &argp->error);
+ if (ret) {
+ snp_page_reclaim(pfn);
+ return ret;
+ }
+
+ svm->vcpu.arch.guest_state_protected = true;
+ }
+
+ return 0;
+}
+
+static int snp_launch_finish(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+ struct sev_data_snp_launch_finish *data;
+ void *id_block = NULL, *id_auth = NULL;
+ struct kvm_sev_snp_launch_finish params;
+ int ret;
+
+ if (!sev_snp_guest(kvm))
+ return -ENOTTY;
+
+ if (!sev->snp_context)
+ return -EINVAL;
+
+ if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data, sizeof(params)))
+ return -EFAULT;
+
+ /* Measure all vCPUs using LAUNCH_UPDATE before we finalize the launch flow. */
+ ret = snp_launch_update_vmsa(kvm, argp);
+ if (ret)
+ return ret;
+
+ data = kzalloc(sizeof(*data), GFP_KERNEL_ACCOUNT);
+ if (!data)
+ return -ENOMEM;
+
+ if (params.id_block_en) {
+ id_block = psp_copy_user_blob(params.id_block_uaddr, KVM_SEV_SNP_ID_BLOCK_SIZE);
+ if (IS_ERR(id_block)) {
+ ret = PTR_ERR(id_block);
+ goto e_free;
+ }
+
+ data->id_block_en = 1;
+ data->id_block_paddr = __sme_pa(id_block);
+ }
+
+ if (params.auth_key_en) {
+ id_auth = psp_copy_user_blob(params.id_auth_uaddr, KVM_SEV_SNP_ID_AUTH_SIZE);
+ if (IS_ERR(id_auth)) {
+ ret = PTR_ERR(id_auth);
+ goto e_free_id_block;
+ }
+
+ data->auth_key_en = 1;
+ data->id_auth_paddr = __sme_pa(id_auth);
+ }
+
+ data->gctx_paddr = __psp_pa(sev->snp_context);
+ ret = sev_issue_cmd(kvm, SEV_CMD_SNP_LAUNCH_FINISH, data, &argp->error);
+
+ kfree(id_auth);
+
+e_free_id_block:
+ kfree(id_block);
+
+e_free:
+ kfree(data);
+
+ return ret;
+}
+
int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
{
struct kvm_sev_cmd sev_cmd;
@@ -1908,6 +2008,9 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
case KVM_SEV_SNP_LAUNCH_UPDATE:
r = snp_launch_update(kvm, &sev_cmd);
break;
+ case KVM_SEV_SNP_LAUNCH_FINISH:
+ r = snp_launch_finish(kvm, &sev_cmd);
+ break;
default:
r = -EINVAL;
goto out;
@@ -2364,16 +2467,29 @@ static void sev_flush_guest_memory(struct vcpu_svm *svm, void *va,
void sev_free_vcpu(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm;
+ u64 pfn;

if (!sev_es_guest(vcpu->kvm))
return;

svm = to_svm(vcpu);
+ pfn = __pa(svm->vmsa) >> PAGE_SHIFT;

if (vcpu->arch.guest_state_protected)
sev_flush_guest_memory(svm, svm->vmsa, PAGE_SIZE);
+
+ /*
+ * If its an SNP guest, then VMSA was added in the RMP entry as
+ * a guest owned page. Transition the page to hyperivosr state
+ * before releasing it back to the system.
+ */
+ if (sev_snp_guest(vcpu->kvm) &&
+ host_rmp_make_shared(pfn, PG_LEVEL_4K, false))
+ goto skip_vmsa_free;
+
__free_page(virt_to_page(svm->vmsa));

+skip_vmsa_free:
if (svm->ghcb_sa_free)
kfree(svm->ghcb_sa);
}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 0681be4bdfdf..ab9b1c82b0ee 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1716,6 +1716,7 @@ enum sev_cmd_id {
KVM_SEV_SNP_INIT,
KVM_SEV_SNP_LAUNCH_START,
KVM_SEV_SNP_LAUNCH_UPDATE,
+ KVM_SEV_SNP_LAUNCH_FINISH,

KVM_SEV_NR_MAX,
};
@@ -1850,6 +1851,19 @@ struct kvm_sev_snp_launch_update {
__u8 vmpl1_perms;
};

+#define KVM_SEV_SNP_ID_BLOCK_SIZE 96
+#define KVM_SEV_SNP_ID_AUTH_SIZE 4096
+#define KVM_SEV_SNP_FINISH_DATA_SIZE 32
+
+struct kvm_sev_snp_launch_finish {
+ __u64 id_block_uaddr;
+ __u64 id_auth_uaddr;
+ __u8 id_block_en;
+ __u8 auth_key_en;
+ __u8 host_data[KVM_SEV_SNP_FINISH_DATA_SIZE];
+ __u8 pad[6];
+};
+
#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)
--
2.17.1