Messages in this thread | | | Date | Mon, 19 Dec 2022 17:24:47 -0600 | Subject | Re: [PATCH RFC v7 40/64] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command | From | "Kalra, Ashish" <> |
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Hello Tom,
On 12/19/2022 12:04 PM, Tom Lendacky wrote: > 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. >
Yes will fix this, the documentation is missing that, the structure defination in include/uapi/linux/kvm.h includes it.
But why do we need this padding ?
>> + }; >> + >> + >> +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. >
Yes will fix this.
Thanks, Ashish
> 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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