[PATCH] target/i386/sev: add the support to query the attestation report

[Brijesh Singh <brijesh.singh@amd.com>]

The SEV FW >= 0.23 added a new command that can be used to query the
attestation report containing the SHA-256 digest of the guest memory
and VMSA encrypted with the LAUNCH_UPDATE and sign it with the PEK.

Note, we already have a command (LAUNCH_MEASURE) that can be used to
query the SHA-256 digest of the guest memory encrypted through the
LAUNCH_UPDATE. The main difference between previous and this command
is that the report is signed with the PEK and unlike the LAUNCH_MEASURE
command the ATTESATION_REPORT command can be called while the guest
is running.

Add a QMP interface "query-sev-attestation-report" that can be used
to get the report encoded in base64.

Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Tom Lendacky <Thomas.Lendacky@amd.com>
Cc: Eric Blake <eblake@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 linux-headers/linux/kvm.h |  8 ++++++
 qapi/misc-target.json     | 38 +++++++++++++++++++++++++++
 target/i386/monitor.c     |  6 +++++
 target/i386/sev-stub.c    |  7 +++++
 target/i386/sev.c         | 54 +++++++++++++++++++++++++++++++++++++++
 target/i386/sev_i386.h    |  2 ++
 6 files changed, 115 insertions(+)

diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h
index 56ce14ad20..6d0f8101ba 100644
--- a/linux-headers/linux/kvm.h
+++ b/linux-headers/linux/kvm.h
@@ -1585,6 +1585,8 @@ enum sev_cmd_id {
 	KVM_SEV_DBG_ENCRYPT,
 	/* Guest certificates commands */
 	KVM_SEV_CERT_EXPORT,
+	/* Attestation report */
+	KVM_SEV_GET_ATTESTATION_REPORT,
 
 	KVM_SEV_NR_MAX,
 };
@@ -1637,6 +1639,12 @@ struct kvm_sev_dbg {
 	__u32 len;
 };
 
+struct kvm_sev_attestation_report {
+	__u8 mnonce[16];
+	__u64 uaddr;
+	__u32 len;
+};
+
 #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)
diff --git a/qapi/misc-target.json b/qapi/misc-target.json
index 1e561fa97b..ec6565e6ef 100644
--- a/qapi/misc-target.json
+++ b/qapi/misc-target.json
@@ -267,3 +267,41 @@
 ##
 { 'command': 'query-gic-capabilities', 'returns': ['GICCapability'],
   'if': 'defined(TARGET_ARM)' }
+
+
+##
+# @SevAttestationReport:
+#
+# The struct describes attestation report for a Secure Encrypted Virtualization
+# feature.
+#
+# @data:  guest attestation report (base64 encoded)
+#
+#
+# Since: 5.2
+##
+{ 'struct': 'SevAttestationReport',
+  'data': { 'data': 'str'},
+  'if': 'defined(TARGET_I386)' }
+
+##
+# @query-sev-attestation-report:
+#
+# This command is used to get the SEV attestation report, and is supported on AMD
+# X86 platforms only.
+#
+# @mnonce: a random 16 bytes of data (it will be included in report)
+#
+# Returns: SevAttestationReport objects.
+#
+# Since: 5.2
+#
+# Example:
+#
+# -> { "execute" : "query-sev-attestation-report", "arguments": { "mnonce": "aaaaaaa" } }
+# <- { "return" : { "data": "aaaaaaaabbbddddd"} }
+#
+##
+{ 'command': 'query-sev-attestation-report', 'data': { 'mnonce': 'str' },
+  'returns': 'SevAttestationReport',
+  'if': 'defined(TARGET_I386)' }
diff --git a/target/i386/monitor.c b/target/i386/monitor.c
index 9f9e1c42f4..a4b65f330c 100644
--- a/target/i386/monitor.c
+++ b/target/i386/monitor.c
@@ -729,3 +729,9 @@ SevCapability *qmp_query_sev_capabilities(Error **errp)
 {
     return sev_get_capabilities(errp);
 }
+
+SevAttestationReport *
+qmp_query_sev_attestation_report(const char *mnonce, Error **errp)
+{
+    return sev_get_attestation_report(mnonce, errp);
+}
diff --git a/target/i386/sev-stub.c b/target/i386/sev-stub.c
index 88e3f39a1e..66d16f53d8 100644
--- a/target/i386/sev-stub.c
+++ b/target/i386/sev-stub.c
@@ -49,3 +49,10 @@ SevCapability *sev_get_capabilities(Error **errp)
     error_setg(errp, "SEV is not available in this QEMU");
     return NULL;
 }
+
+SevAttestationReport *
+sev_get_attestation_report(const char *mnonce, Error **errp)
+{
+    error_setg(errp, "SEV is not available in this QEMU");
+    return NULL;
+}
diff --git a/target/i386/sev.c b/target/i386/sev.c
index 93c4d60b82..28958fb71b 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -68,6 +68,7 @@ struct SevGuestState {
 
 #define DEFAULT_GUEST_POLICY    0x1 /* disable debug */
 #define DEFAULT_SEV_DEVICE      "/dev/sev"
+#define DEFAULT_ATTESATION_REPORT_BUF_SIZE      4096
 
 static SevGuestState *sev_guest;
 static Error *sev_mig_blocker;
@@ -490,6 +491,59 @@ out:
     return cap;
 }
 
+SevAttestationReport *
+sev_get_attestation_report(const char *mnonce, Error **errp)
+{
+    struct kvm_sev_attestation_report input = {};
+    SevGuestState *sev = sev_guest;
+    SevAttestationReport *report;
+    guchar *data;
+    int err = 0, ret;
+
+    if (!sev_enabled()) {
+        error_setg(errp, "SEV is not enabled");
+        return NULL;
+    }
+
+    /* Verify that user provided random data length */
+    if (strlen(mnonce) != sizeof(input.mnonce)) {
+        error_setg(errp, "Expected mnonce data len %ld got %ld",
+                sizeof(input.mnonce), strlen(mnonce));
+        return NULL;
+    }
+
+    /* Query the report length */
+    ret = sev_ioctl(sev->sev_fd, KVM_SEV_GET_ATTESTATION_REPORT,
+            &input, &err);
+    if (ret < 0) {
+        if (err != SEV_RET_INVALID_LEN) {
+            error_setg(errp, "failed to query the attestation report length "
+                    "ret=%d fw_err=%d (%s)", ret, err, fw_error_to_str(err));
+            return NULL;
+        }
+    }
+
+    data = g_malloc(input.len);
+    input.uaddr = (unsigned long)data;
+    memcpy(input.mnonce, mnonce, sizeof(input.mnonce));
+
+    /* Query the report */
+    ret = sev_ioctl(sev->sev_fd, KVM_SEV_GET_ATTESTATION_REPORT,
+            &input, &err);
+    if (ret) {
+        error_setg_errno(errp, errno, "Failed to get attestation report"
+                " ret=%d fw_err=%d (%s)", ret, err, fw_error_to_str(err));
+        goto e_free_data;
+    }
+
+    report = g_new0(SevAttestationReport, 1);
+    report->data = g_base64_encode(data, input.len);
+
+e_free_data:
+    g_free(data);
+    return report;
+}
+
 static int
 sev_read_file_base64(const char *filename, guchar **data, gsize *len)
 {
diff --git a/target/i386/sev_i386.h b/target/i386/sev_i386.h
index 4db6960f60..e2d0774708 100644
--- a/target/i386/sev_i386.h
+++ b/target/i386/sev_i386.h
@@ -35,5 +35,7 @@ extern uint32_t sev_get_cbit_position(void);
 extern uint32_t sev_get_reduced_phys_bits(void);
 extern char *sev_get_launch_measurement(void);
 extern SevCapability *sev_get_capabilities(Error **errp);
+extern SevAttestationReport *
+sev_get_attestation_report(const char *mnonce, Error **errp);
 
 #endif
-- 
2.17.1