[RFC PATCH v2 31/32] 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 64899ed..13996d6 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6141,6 +6141,54 @@ static int sev_dbg_encrypt(struct kvm *kvm, struct 
kvm_sev_cmd *argp)
        return ret;
 }
 
+static int sev_launch_measure(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+       int ret;
+       void *addr = NULL;
+       struct kvm_sev_launch_measure params;
+       struct sev_data_launch_measure *data;
+
+       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 err_1;
+               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 err_1;
+       }
+
+       params.length = data->length;
+       if (copy_to_user((void *)argp->data, &params,
+                               sizeof(struct kvm_sev_launch_measure)))
+               ret = -EFAULT;
+
+       kfree(addr);
+err_1:
+       kfree(data);
+       return ret;
+}
+
 static int amd_memory_encryption_cmd(struct kvm *kvm, void __user *argp)
 {
        int r = -ENOTTY;
@@ -6176,6 +6224,10 @@ static int amd_memory_encryption_cmd(struct kvm *kvm, 
void __user *argp)
                r = sev_dbg_encrypt(kvm, &sev_cmd);
                break;
        }
+       case KVM_SEV_LAUNCH_MEASURE: {
+               r = sev_launch_measure(kvm, &sev_cmd);
+               break;
+       }
        default:
                break;
        }