Re: [PATCH RFC v7 40/64] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command
From: Kalra, Ashish
Date: Mon Dec 19 2022 - 18:25:07 EST
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@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Harald Hoyer <harald@xxxxxxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
---
.../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)