[PATCH v2 2/2] sev: update sev-inject-launch-secret to make gpa optional

[James Bottomley <jejb@linux.ibm.com>]

If the gpa isn't specified, it's value is extracted from the OVMF
properties table located below the reset vector (and if this doesn't
exist, an error is returned).  OVMF has defined the GUID for the SEV
secret area as 4c2eb361-7d9b-4cc3-8081-127c90d3d294 and the format of
the <data> is: <base>|<size> where both are uint32_t.  We extract
<base> and use it as the gpa for the injection.

Note: it is expected that the injected secret will also be GUID
described but since qemu can't interpret it, the format is left
undefined here.

Signed-off-by: James Bottomley <jejb@linux.ibm.com>

---

v2: fix line length warning, add more comments about sev area
---
 qapi/misc-target.json |  2 +-
 target/i386/monitor.c | 27 ++++++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/qapi/misc-target.json b/qapi/misc-target.json
index 06ef8757f0..0c7491cd82 100644
--- a/qapi/misc-target.json
+++ b/qapi/misc-target.json
@@ -216,7 +216,7 @@
 #
 ##
 { 'command': 'sev-inject-launch-secret',
-  'data': { 'packet-header': 'str', 'secret': 'str', 'gpa': 'uint64' },
+  'data': { 'packet-header': 'str', 'secret': 'str', '*gpa': 'uint64' },
   'if': 'defined(TARGET_I386)' }
 
 ##
diff --git a/target/i386/monitor.c b/target/i386/monitor.c
index 1bc91442b1..11bdb04155 100644
--- a/target/i386/monitor.c
+++ b/target/i386/monitor.c
@@ -34,6 +34,7 @@
 #include "sev_i386.h"
 #include "qapi/qapi-commands-misc-target.h"
 #include "qapi/qapi-commands-misc.h"
+#include "hw/i386/pc.h"
 
 /* Perform linear address sign extension */
 static hwaddr addr_canonical(CPUArchState *env, hwaddr addr)
@@ -730,9 +731,33 @@ SevCapability *qmp_query_sev_capabilities(Error **errp)
     return sev_get_capabilities(errp);
 }
 
+#define SEV_SECRET_GUID "4c2eb361-7d9b-4cc3-8081-127c90d3d294"
+struct sev_secret_area {
+    uint32_t base;
+    uint32_t size;
+};
+
 void qmp_sev_inject_launch_secret(const char *packet_hdr,
-                                  const char *secret, uint64_t gpa,
+                                  const char *secret,
+                                  bool has_gpa, uint64_t gpa,
                                   Error **errp)
 {
+    if (!has_gpa) {
+        uint8_t *data;
+        struct sev_secret_area *area;
+
+        /*
+         * not checking length means that this area can't be versioned
+         * by length and would have to be replaced if updated
+         */
+        if (!pc_system_ovmf_table_find(SEV_SECRET_GUID, &data, NULL)) {
+            error_setg(errp, "SEV: no secret area found in OVMF,"
+                       " gpa must be specified.");
+            return;
+        }
+        area = (struct sev_secret_area *)data;
+        gpa = area->base;
+    }
+
     sev_inject_launch_secret(packet_hdr, secret, gpa, errp);
 }
-- 
2.26.2