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Date: Mon, 19 Dec 2022 12:04:26 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: Michael Roth <michael.roth@....com>, kvm@...r.kernel.org
Cc: linux-coco@...ts.linux.dev, linux-mm@...ck.org,
linux-crypto@...r.kernel.org, x86@...nel.org,
linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
jroedel@...e.de, hpa@...or.com, ardb@...nel.org,
pbonzini@...hat.com, seanjc@...gle.com, vkuznets@...hat.com,
wanpengli@...cent.com, jmattson@...gle.com, luto@...nel.org,
dave.hansen@...ux.intel.com, slp@...hat.com, pgonda@...gle.com,
peterz@...radead.org, srinivas.pandruvada@...ux.intel.com,
rientjes@...gle.com, dovmurik@...ux.ibm.com, tobin@....com,
bp@...en8.de, vbabka@...e.cz, kirill@...temov.name,
ak@...ux.intel.com, tony.luck@...el.com, marcorr@...gle.com,
sathyanarayanan.kuppuswamy@...ux.intel.com, alpergun@...gle.com,
dgilbert@...hat.com, jarkko@...nel.org, ashish.kalra@....com,
harald@...fian.com, Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH RFC v7 40/64] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH
command
On 12/14/22 13:40, Michael Roth wrote:
> From: Brijesh Singh <brijesh.singh@....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@....com>
> Signed-off-by: Harald Hoyer <harald@...fian.com>
> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
> Signed-off-by: Michael Roth <michael.roth@....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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