sev/i386: add support to LAUNCH_MEASURE command

During machine creation we encrypted the guest bios image, the
LAUNCH_MEASURE command can be used to retrieve the measurement of
the encrypted memory region. This measurement is a signature of
the memory contents that can be sent to the guest owner as an
attestation that the memory was encrypted correctly by the firmware.
VM management tools like libvirt can query the measurement using
query-sev-launch-measure QMP command.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/sev-stub.c b/target/i386/sev-stub.c
index c86d8c1392379e6a134d88f612fe50bf48335975..2f61c32ec975cc0b553e5e00a4ca8ab9ac854796 100644 (file)
--- a/target/i386/sev-stub.c
+++ b/target/i386/sev-stub.c
@@ -39,3 +39,8 @@ uint32_t sev_get_reduced_phys_bits(void)
 {
     return 0;
 }
+
+char *sev_get_launch_measurement(void)
+{
+    return NULL;
+}

diff --git a/target/i386/sev.c b/target/i386/sev.c
index 2d14879166efeb77701a797b02fadd9a82f85564..0132beaf24b4610d044d583f2b1c6fa78287dd88 100644 (file)
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -516,6 +516,68 @@ sev_launch_update_data(uint8_t *addr, uint64_t len)
     return ret;
 }
 
+static void
+sev_launch_get_measure(Notifier *notifier, void *unused)
+{
+    int ret, error;
+    guchar *data;
+    SEVState *s = sev_state;
+    struct kvm_sev_launch_measure *measurement;
+
+    if (!sev_check_state(SEV_STATE_LAUNCH_UPDATE)) {
+        return;
+    }
+
+    measurement = g_new0(struct kvm_sev_launch_measure, 1);
+
+    /* query the measurement blob length */
+    ret = sev_ioctl(sev_state->sev_fd, KVM_SEV_LAUNCH_MEASURE,
+                    measurement, &error);
+    if (!measurement->len) {
+        error_report("%s: LAUNCH_MEASURE ret=%d fw_error=%d '%s'",
+                     __func__, ret, error, fw_error_to_str(errno));
+        goto free_measurement;
+    }
+
+    data = g_new0(guchar, measurement->len);
+    measurement->uaddr = (unsigned long)data;
+
+    /* get the measurement blob */
+    ret = sev_ioctl(sev_state->sev_fd, KVM_SEV_LAUNCH_MEASURE,
+                    measurement, &error);
+    if (ret) {
+        error_report("%s: LAUNCH_MEASURE ret=%d fw_error=%d '%s'",
+                     __func__, ret, error, fw_error_to_str(errno));
+        goto free_data;
+    }
+
+    sev_set_guest_state(SEV_STATE_LAUNCH_SECRET);
+
+    /* encode the measurement value and emit the event */
+    s->measurement = g_base64_encode(data, measurement->len);
+    trace_kvm_sev_launch_measurement(s->measurement);
+
+free_data:
+    g_free(data);
+free_measurement:
+    g_free(measurement);
+}
+
+char *
+sev_get_launch_measurement(void)
+{
+    if (sev_state &&
+        sev_state->state >= SEV_STATE_LAUNCH_SECRET) {
+        return g_strdup(sev_state->measurement);
+    }
+
+    return NULL;
+}
+
+static Notifier sev_machine_done_notify = {
+    .notify = sev_launch_get_measure,
+};
+
 void *
 sev_guest_init(const char *id)
 {
@@ -593,6 +655,7 @@ sev_guest_init(const char *id)
     }
 
     ram_block_notifier_add(&sev_ram_notifier);
+    qemu_add_machine_init_done_notifier(&sev_machine_done_notify);
 
     return s;
 err:

diff --git a/target/i386/sev_i386.h b/target/i386/sev_i386.h
index 924cebcab02d4be39e758f15bfbd8280f8bd7996..6e370775770e8028ad1af7105d7d81594848d908 100644 (file)
--- a/target/i386/sev_i386.h
+++ b/target/i386/sev_i386.h
@@ -37,6 +37,7 @@ extern uint64_t sev_get_me_mask(void);
 extern SevInfo *sev_get_info(void);
 extern uint32_t sev_get_cbit_position(void);
 extern uint32_t sev_get_reduced_phys_bits(void);
+extern char *sev_get_launch_measurement(void);
 
 typedef struct QSevGuestInfo QSevGuestInfo;
 typedef struct QSevGuestInfoClass QSevGuestInfoClass;
@@ -78,6 +79,7 @@ struct SEVState {
     uint32_t handle;
     int sev_fd;
     SevState state;
+    gchar *measurement;
 };
 
 typedef struct SEVState SEVState;

diff --git a/target/i386/trace-events b/target/i386/trace-events
index 4aa87ef3eeb54483b8bd94daf5c292ab8daa8d2c..ce6c71b375c2cd6b0ec9fdf6f2b4024b786859ce 100644 (file)
--- a/target/i386/trace-events
+++ b/target/i386/trace-events
@@ -13,3 +13,4 @@ kvm_memcrypt_unregister_region(void *addr, size_t len) "addr %p len 0x%zu"
 kvm_sev_change_state(const char *old, const char *new) "%s -> %s"
 kvm_sev_launch_start(int policy, void *session, void *pdh) "policy 0x%x session %p pdh %p"
 kvm_sev_launch_update_data(void *addr, uint64_t len) "addr %p len 0x%" PRIu64
+kvm_sev_launch_measurement(const char *value) "data %s"