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    Subject[PATCH Part2 RFC v4 26/40] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command
    Date
    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 | 125 ++++++++++++++++++
    include/uapi/linux/kvm.h | 13 ++
    3 files changed, 160 insertions(+)

    diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
    index 60ace54438c3..a3d863e88869 100644
    --- a/Documentation/virt/kvm/amd-memory-encryption.rst
    +++ b/Documentation/virt/kvm/amd-memory-encryption.rst
    @@ -495,6 +495,28 @@ 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 4468995dd209..3f8824c9a5dc 100644
    --- a/arch/x86/kvm/svm/sev.c
    +++ b/arch/x86/kvm/svm/sev.c
    @@ -1763,6 +1763,111 @@ 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]);
    + struct rmpupdate e = {};
    +
    + /* 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. */
    + e.assigned = 1;
    + e.immutable = 1;
    + e.asid = sev->asid;
    + e.gpa = -1;
    + e.pagesize = RMP_PG_SIZE_4K;
    + ret = rmpupdate(virt_to_page(svm->vmsa), &e);
    + 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(virt_to_page(svm->vmsa), RMP_PG_SIZE_4K);
    + 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;
    @@ -1858,6 +1963,9 @@ 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;
    @@ -2346,8 +2454,25 @@ void sev_free_vcpu(struct kvm_vcpu *vcpu)

    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)) {
    + struct rmpupdate e = {};
    + int rc;
    +
    + rc = rmpupdate(virt_to_page(svm->vmsa), &e);
    + if (rc) {
    + pr_err("Failed to release SNP guest VMSA page (rc %d), leaking it\n", rc);
    + 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 c9b453fb31d4..fb3f6e1defd9 100644
    --- a/include/uapi/linux/kvm.h
    +++ b/include/uapi/linux/kvm.h
    @@ -1682,6 +1682,7 @@ enum sev_cmd_id {
    KVM_SEV_SNP_INIT = 256,
    KVM_SEV_SNP_LAUNCH_START,
    KVM_SEV_SNP_LAUNCH_UPDATE,
    + KVM_SEV_SNP_LAUNCH_FINISH,

    KVM_SEV_NR_MAX,
    };
    @@ -1808,6 +1809,18 @@ 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];
    +};
    +
    #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
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