[RFC Part2 PATCH v3 17/26] KVM: SVM: Add support for SEV LAUNCH_MEASURE command

[Brijesh Singh]

The command is used to retrieve the measurement of memory encrypted
through the LAUNCH_UPDATE_DATA command. This measurement can be used
for attestation purposes.

Signed-off-by: Brijesh Singh <brijesh.si...@amd.com>
---
 arch/x86/kvm/svm.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 91b070f..9b672eb 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5957,6 +5957,54 @@ static int sev_launch_update_data(struct kvm *kvm, 
struct kvm_sev_cmd *argp)
        return ret;
 }
 
+static int sev_launch_measure(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+       struct sev_data_launch_measure *data = NULL;
+       struct kvm_sev_launch_measure params;
+       void *addr = NULL;
+       int ret;
+
+       if (!sev_guest(kvm))
+               return -ENOTTY;
+
+       if (copy_from_user(&params, (void *)argp->data,
+                               sizeof(struct kvm_sev_launch_measure)))
+               return -EFAULT;
+
+       data = kzalloc(sizeof(*data), GFP_KERNEL);
+       if (!data)
+               return -ENOMEM;
+
+       if (params.address && params.length) {
+               ret = -EFAULT;
+               addr = kzalloc(params.length, GFP_KERNEL);
+               if (!addr)
+                       goto e_free;
+               data->address = __psp_pa(addr);
+               data->length = params.length;
+       }
+
+       data->handle = sev_get_handle(kvm);
+       ret = sev_issue_cmd(kvm, SEV_CMD_LAUNCH_MEASURE, data, &argp->error);
+
+       /* copy the measurement to userspace */
+       if (addr &&
+               copy_to_user((void *)params.address, addr, params.length)) {
+               ret = -EFAULT;
+               goto e_free;
+       }
+
+       params.length = data->length;
+       if (copy_to_user((void *)argp->data, &params,
+                               sizeof(struct kvm_sev_launch_measure)))
+               ret = -EFAULT;
+
+e_free:
+       kfree(addr);
+       kfree(data);
+       return ret;
+}
+
 static int svm_memory_encryption_op(struct kvm *kvm, void __user *argp)
 {
        struct kvm_sev_cmd sev_cmd;
@@ -5980,6 +6028,10 @@ static int svm_memory_encryption_op(struct kvm *kvm, 
void __user *argp)
                r = sev_launch_update_data(kvm, &sev_cmd);
                break;
        }
+       case KVM_SEV_LAUNCH_MEASURE: {
+               r = sev_launch_measure(kvm, &sev_cmd);
+               break;
+       }
        default:
                break;
        }
-- 
2.9.4