Introduce a new command for KVM_MEMORY_ENCRYPT_OP ioctl that can be used
to enable fetching of endorsement key certificates from userspace via
the new KVM_EXIT_SNP_REQ_CERTS exit type. Also introduce a new
KVM_X86_SEV_SNP_REQ_CERTS KVM device attribute so that userspace can
query whether the kernel supports the new command/exit.
Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
---
.../virt/kvm/x86/amd-memory-encryption.rst | 17 ++++++++++++++++-
arch/x86/include/uapi/asm/kvm.h | 2 ++
arch/x86/kvm/svm/sev.c | 17 ++++++++++++++++-
3 files changed, 34 insertions(+), 2 deletions(-)
diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
index 1ddb6a86ce7f..cd680f129431 100644
--- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
@@ -572,6 +572,17 @@ Returns: 0 on success, -negative on error
See SNP_LAUNCH_FINISH in the SEV-SNP specification [snp-fw-abi]_ for further
details on the input parameters in ``struct kvm_sev_snp_launch_finish``.
+21. KVM_SEV_SNP_ENABLE_REQ_CERTS
+--------------------------------
+
+The KVM_SEV_SNP_ENABLE_REQ_CERTS command will configure KVM to exit to
+userspace with a ``KVM_EXIT_SNP_REQ_CERTS`` exit type as part of handling
+a guest attestation report, which will to allow userspace to provide a
+certificate corresponding to the endorsement key used by firmware to sign
+that attestation report.
+
+Returns: 0 on success, -negative on error
+
Device attribute API
====================
@@ -579,11 +590,15 @@ Attributes of the SEV implementation can be retrieved through the
``KVM_HAS_DEVICE_ATTR`` and ``KVM_GET_DEVICE_ATTR`` ioctls on the ``/dev/kvm``
device node, using group ``KVM_X86_GRP_SEV``.
-Currently only one attribute is implemented:
+The following attributes are currently implemented:
* ``KVM_X86_SEV_VMSA_FEATURES``: return the set of all bits that
are accepted in the ``vmsa_features`` of ``KVM_SEV_INIT2``.
+* ``KVM_X86_SEV_SNP_REQ_CERTS``: return a value of 1 if the kernel supports the
+ ``KVM_EXIT_SNP_REQ_CERTS`` exit, which allows for fetching endorsement key
+ certificates from userspace for each SNP attestation request the guest issues.
+
Firmware Management
===================
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 225a12e0d5d6..24045279dbea 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -468,6 +468,7 @@ struct kvm_sync_regs {
/* vendor-specific groups and attributes for system fd */
#define KVM_X86_GRP_SEV 1
# define KVM_X86_SEV_VMSA_FEATURES 0
+# define KVM_X86_SEV_SNP_REQ_CERTS 1
struct kvm_vmx_nested_state_data {
__u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
@@ -708,6 +709,7 @@ enum sev_cmd_id {
KVM_SEV_SNP_LAUNCH_START = 100,
KVM_SEV_SNP_LAUNCH_UPDATE,
KVM_SEV_SNP_LAUNCH_FINISH,
+ KVM_SEV_SNP_ENABLE_REQ_CERTS,
KVM_SEV_NR_MAX,
};
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index b74e2be2cbaf..d5b4f308ab3a 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2123,7 +2123,9 @@ int sev_dev_get_attr(u32 group, u64 attr, u64 *val)
case KVM_X86_SEV_VMSA_FEATURES:
*val = sev_supported_vmsa_features;
return 0;
-
+ case KVM_X86_SEV_SNP_REQ_CERTS:
+ *val = sev_snp_enabled ? 1 : 0;
+ return 0;
default:
return -ENXIO;
}
@@ -2535,6 +2537,16 @@ static int snp_launch_finish(struct kvm *kvm, struct kvm_sev_cmd *argp)
return ret;
}
+static int snp_enable_certs(struct kvm *kvm)
+{
+ if (kvm->created_vcpus || !sev_snp_guest(kvm))
+ return -EINVAL;
+
+ to_kvm_sev_info(kvm)->snp_certs_enabled = true;
+
+ return 0;
+}
+
int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
{
struct kvm_sev_cmd sev_cmd;
@@ -2640,6 +2652,9 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
case KVM_SEV_SNP_LAUNCH_FINISH:
r = snp_launch_finish(kvm, &sev_cmd);
break;
+ case KVM_SEV_SNP_ENABLE_REQ_CERTS:
+ r = snp_enable_certs(kvm);
+ break;
default:
r = -EINVAL;
goto out;
--
2.25.1
