Messages in this thread | | | Date | Mon, 19 Dec 2022 12:04:26 -0600 | Subject | Re: [PATCH RFC v7 40/64] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command | From | Tom Lendacky <> |
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On 12/14/22 13:40, Michael Roth 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. > > 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: Harald Hoyer <harald@profian.com> > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > Signed-off-by: Michael Roth <michael.roth@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 c94be8e6d657..e4b42aaab1de 100644 > --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst > +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst > @@ -513,6 +513,28 @@ 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];
This is missing the 6 bytes of padding at the end of the struct.
> + }; > + > + > +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 379e61a9226a..6f901545bed9 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -2243,6 +2243,106 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp) > snp_launch_update_gfn_handler, argp); > } > > +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 kvm_sev_snp_launch_finish params; > + struct sev_data_snp_launch_finish *data; > + void *id_block = NULL, *id_auth = NULL; > + int ret; > + > + if (!sev_snp_guest(kvm)) > + return -ENOTTY; > + > + if (!sev->snp_context) > + return -EINVAL; > + > + if (copy_from_user(¶ms, (void __user *)(uintptr_t)argp->data, sizeof(params))) > + return -EFAULT; > + > + /* Measure all vCPUs using LAUNCH_UPDATE before finalizing 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); > + > + 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->id_auth_paddr = __sme_pa(id_auth); > + > + if (params.auth_key_en) > + data->auth_key_en = 1; > + } > + > + data->gctx_paddr = __psp_pa(sev->snp_context);
This is missing the copying of the params.host_data field into the data->host_data field. This is needed so that the host_data shows up in the attestation report.
Thanks, Tom
> + 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; > @@ -2339,6 +2439,9 @@ 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; > @@ -2794,11 +2897,27 @@ 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, true)) > + 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 9b6c95cc62a8..c468adc1f147 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -1942,6 +1942,7 @@ 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, > }; > @@ -2076,6 +2077,19 @@ 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)
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