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    SubjectRe: [PATCH Part2 v6 28/49] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command
    On Mon, Jun 20, 2022 at 11:08:38PM +0000, Ashish Kalra wrote:
    > From: Brijesh Singh <brijesh.singh@amd.com>
    >
    > 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.

    Nit: for completeness sake it would nice to fully conclude whether
    LAUNCH_UPDATE is usable after LAUNCH_FINISH in this paragraph.

    >
    > If its an SNP guest, then VMSA was added in the RMP entry as
    > a guest owned page and also removed from the kernel direct map
    > so flush it later after it is transitioned back to hypervisor
    > state and restored in the direct map.
    >
    > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
    > ---
    > .../virt/kvm/x86/amd-memory-encryption.rst | 22 ++++
    > arch/x86/kvm/svm/sev.c | 119 ++++++++++++++++++
    > include/uapi/linux/kvm.h | 14 +++
    > 3 files changed, 155 insertions(+)
    >
    > diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
    > index 62abd5c1f72b..750162cff87b 100644
    > --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst
    > +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
    > @@ -514,6 +514,28 @@ 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.

    Some remark about LAUNCH_UPDATE post-LAUNCH_FINISH would be nice.

    > +
    > +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 a9461d352eda..a5b90469683f 100644
    > --- a/arch/x86/kvm/svm/sev.c
    > +++ b/arch/x86/kvm/svm/sev.c
    > @@ -2095,6 +2095,106 @@ 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(xa_load(&kvm->vcpu_array, i));
    > + u64 pfn = __pa(svm->sev_es.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->sev_es.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;

    Nit: "params" should be the 2nd declaration (reverse
    christmas tree order).

    > + 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 sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
    > {
    > struct kvm_sev_cmd sev_cmd;
    > @@ -2191,6 +2291,9 @@ int sev_mem_enc_ioctl(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;
    > @@ -2696,11 +2799,27 @@ void sev_free_vcpu(struct kvm_vcpu *vcpu)
    >
    > svm = to_svm(vcpu);
    >
    > + /*
    > + * If its an SNP guest, then VMSA was added in the RMP entry as
    > + * a guest owned page. Transition the page to hypervisor state
    > + * before releasing it back to the system.
    > + * Also the page is removed from the kernel direct map, so flush it
    > + * later after it is transitioned back to hypervisor state and
    > + * restored in the direct map.
    > + */
    > + if (sev_snp_guest(vcpu->kvm)) {
    > + u64 pfn = __pa(svm->sev_es.vmsa) >> PAGE_SHIFT;
    > +
    > + if (host_rmp_make_shared(pfn, PG_LEVEL_4K, false))
    > + goto skip_vmsa_free;
    > + }
    > +
    > if (vcpu->arch.guest_state_protected)
    > sev_flush_encrypted_page(vcpu, svm->sev_es.vmsa);
    >
    > __free_page(virt_to_page(svm->sev_es.vmsa));
    >
    > +skip_vmsa_free:
    > if (svm->sev_es.ghcb_sa_free)
    > kvfree(svm->sev_es.ghcb_sa);
    > }
    > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
    > index 9b36b07414ea..5a4662716b6a 100644
    > --- a/include/uapi/linux/kvm.h
    > +++ b/include/uapi/linux/kvm.h
    > @@ -1814,6 +1814,7 @@ 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,
    > };
    > @@ -1948,6 +1949,19 @@ 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)
    > --
    > 2.25.1
    >

    BR, Jarkko

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