qemu_firmware: Try to autofill for old style UEFI specification

While we discourage people to use the old style of specifying
UEFI for their domains (the old style is putting path to the FW
image under /domain/os/loader/ whilst the new one is using
/domain/os/@firmware), some applications might have not adapted
yet. They still rely on libvirt autofilling NVRAM path and
figuring out NVRAM template when using the old way (notably
virt-install does this). We must preserve backcompat for this
previously supported config approach. However, since we really
want distro maintainers to leave --with-loader-nvram configure
option and rely on JSON descriptors, we need to implement
autofilling of NVRAM template for the old way too.

Fedora: https://bugzilla.redhat.com/show_bug.cgi?id=1782778
RHEL: https://bugzilla.redhat.com/show_bug.cgi?id=1776949Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

src/qemu/qemu_firmware.c

@@ -959,6 +959,21 @@ qemuFirmwareMatchDomain(const virDomainDef *def,
 
     want = qemuFirmwareOSInterfaceTypeFromOsDefFirmware(def->os.firmware);
 
+    if (want == QEMU_FIRMWARE_OS_INTERFACE_NONE &&
+        def->os.loader) {
+        want = qemuFirmwareOSInterfaceTypeFromOsDefFirmware(def->os.loader->type);
+
+        if (fw->mapping.device != QEMU_FIRMWARE_DEVICE_FLASH ||
+            STRNEQ(def->os.loader->path, fw->mapping.data.flash.executable.filename)) {
+            VIR_DEBUG("Not matching FW interface %s or loader "
+                      "path '%s' for user provided path '%s'",
+                      qemuFirmwareDeviceTypeToString(fw->mapping.device),
+                      fw->mapping.data.flash.executable.filename,
+                      def->os.loader->path);
+            return false;
+        }
+    }
+
     for (i = 0; i < fw->ninterfaces; i++) {
         if (fw->interfaces[i] == want)
             break;
@@ -1226,14 +1241,29 @@ qemuFirmwareFillDomain(virQEMUDriverPtr driver,
     qemuFirmwarePtr *firmwares = NULL;
     ssize_t nfirmwares = 0;
     const qemuFirmware *theone = NULL;
+    bool needResult = true;
     size_t i;
     int ret = -1;
 
     if (!(flags & VIR_QEMU_PROCESS_START_NEW))
         return 0;
 
-    if (def->os.firmware == VIR_DOMAIN_OS_DEF_FIRMWARE_NONE)
-        return 0;
+    /* Fill in FW paths if either os.firmware is enabled, or
+     * loader path was provided with no nvram varstore. */
+    if (def->os.firmware == VIR_DOMAIN_OS_DEF_FIRMWARE_NONE) {
+        /* This is horrific check, but loosely said, if UEFI
+         * image was provided by the old method (by specifying
+         * its path in domain XML) but no template for NVRAM was
+         * specified and the varstore doesn't exist ... */
+        if (!virDomainDefHasOldStyleROUEFI(def) ||
+            def->os.loader->templt ||
+            virFileExists(def->os.loader->nvram))
+            return 0;
+
+        /* ... then we want to consult JSON FW descriptors first,
+         * but we don't want to fail if we haven't found a match. */
+        needResult = false;
+    }
 
     if ((nfirmwares = qemuFirmwareFetchParsedConfigs(driver->privileged,
                                                      &firmwares, &paths)) < 0)
@@ -1249,9 +1279,16 @@ qemuFirmwareFillDomain(virQEMUDriverPtr driver,
     }
 
     if (!theone) {
-        virReportError(VIR_ERR_OPERATION_FAILED,
-                       _("Unable to find any firmware to satisfy '%s'"),
-                       virDomainOsDefFirmwareTypeToString(def->os.firmware));
+        if (needResult) {
+            virReportError(VIR_ERR_OPERATION_FAILED,
+                           _("Unable to find any firmware to satisfy '%s'"),
+                           virDomainOsDefFirmwareTypeToString(def->os.firmware));
+        } else {
+            VIR_DEBUG("Unable to find NVRAM template for '%s', "
+                      "falling back to old style",
+                      NULLSTR(def->os.loader ? def->os.loader->path : NULL));
+            ret = 0;
+        }
         goto cleanup;
     }