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Message-ID: <5e27ed72-2cb0-0bdd-3234-58ff75cf7d44@amd.com>
Date: Mon, 19 Dec 2022 17:24:47 -0600
From: "Kalra, Ashish" <ashish.kalra@....com>
To: Tom Lendacky <thomas.lendacky@....com>,
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, harald@...fian.com,
Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH RFC v7 40/64] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH
command
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@....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.
>
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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