[Qemu-devel] [PATCH 5/6] fw_cfg: insert fw_cfg file blobs via qemu cmdline

["Gabriel L. Somlo" <somlo@cmu.edu>]

Allow user supplied files to be inserted into the fw_cfg
device before starting the guest. Since fw_cfg_add_file()
already disallows duplicate fw_cfg file names, qemu will
exit with an error message if the user supplies multiple
blobs with the same fw_cfg file name, or if a blob name
collides with a fw_cfg name used internally by qemu.

Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
---
 hw/nvram/fw_cfg.c         | 48 +++++++++++++++++++++++++++++++++++++++++++++++
 include/hw/nvram/fw_cfg.h |  4 ++++
 qemu-options.hx           | 10 ++++++++++
 vl.c                      | 27 ++++++++++++++++++++++++++
 4 files changed, 89 insertions(+)

diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 86f120e..70e9805 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -29,6 +29,7 @@
 #include "trace.h"
 #include "qemu/error-report.h"
 #include "qemu/config-file.h"
+#include "hw/loader.h"
 
 #define FW_CFG_SIZE 2
 #define FW_CFG_NAME "fw_cfg"
@@ -549,6 +550,51 @@ static void fw_cfg_machine_ready(struct Notifier *n, void *data)
 }
 
 
+static struct FWCfgOption {
+    const char *name;
+    const char *file;
+} *fw_cfg_options;
+static int fw_cfg_num_options;
+
+void fw_cfg_option_add(QemuOpts *opts)
+{
+    const char *name = qemu_opt_get(opts, "name");
+    const char *file = qemu_opt_get(opts, "file");
+
+    if (name == NULL || *name == '\0' || file == NULL || *file == '\0') {
+        error_report("invalid argument value");
+        exit(1);
+    }
+
+    fw_cfg_options = g_realloc(fw_cfg_options, sizeof(struct FWCfgOption) *
+                                               (fw_cfg_num_options + 1));
+    fw_cfg_options[fw_cfg_num_options].name = name;
+    fw_cfg_options[fw_cfg_num_options].file = file;
+    fw_cfg_num_options++;
+}
+
+static void fw_cfg_options_insert(FWCfgState *s)
+{
+    int i, filesize;
+    const char *filename;
+    void *filebuf;
+
+    for (i = 0; i < fw_cfg_num_options; i++) {
+        filename = fw_cfg_options[i].file;
+        filesize = get_image_size(filename);
+        if (filesize == -1) {
+            error_report("Cannot read fw_cfg file %s", filename);
+            exit(1);
+        }
+        filebuf = g_malloc(filesize);
+        if (load_image(filename, filebuf) != filesize) {
+            error_report("Failed to load fw_cfg file %s", filename);
+            exit(1);
+        }
+        fw_cfg_add_file(s, fw_cfg_options[i].name, filebuf, filesize);
+    }
+}
+
 
 static void fw_cfg_init1(DeviceState *dev)
 {
@@ -560,6 +606,8 @@ static void fw_cfg_init1(DeviceState *dev)
 
     qdev_init_nofail(dev);
 
+    fw_cfg_options_insert(s);
+
     fw_cfg_add_bytes(s, FW_CFG_SIGNATURE, (char *)"QEMU", 4);
     fw_cfg_add_bytes(s, FW_CFG_UUID, qemu_uuid, 16);
     fw_cfg_add_i16(s, FW_CFG_NOGRAPHIC, (uint16_t)(display_type == DT_NOGRAPHIC));
diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index f11d7d5..20a62d4 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -7,6 +7,7 @@
 
 #include "exec/hwaddr.h"
 #include "qemu/typedefs.h"
+#include "qemu/option.h"
 #endif
 
 #define FW_CFG_SIGNATURE        0x00
@@ -76,6 +77,9 @@ void fw_cfg_add_file_callback(FWCfgState *s, const char *filename,
                               void *data, size_t len);
 void *fw_cfg_modify_file(FWCfgState *s, const char *filename, void *data,
                          size_t len);
+
+void fw_cfg_option_add(QemuOpts *opts);
+
 FWCfgState *fw_cfg_init_io(uint32_t iobase);
 FWCfgState *fw_cfg_init_mem(hwaddr ctl_addr, hwaddr data_addr);
 FWCfgState *fw_cfg_init_mem_wide(hwaddr ctl_addr, hwaddr data_addr,
diff --git a/qemu-options.hx b/qemu-options.hx
index 3c852f1..94ce91b 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2668,6 +2668,16 @@ STEXI
 @table @option
 ETEXI
 
+DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
+    "-fw_cfg name=<name>,file=<file>\n"
+    "                add named fw_cfg blob from file\n",
+    QEMU_ARCH_ALL)
+STEXI
+@item -fw_cfg name=@var{name},file=@var{file}
+@findex -fw_cfg
+Add named fw_cfg blob from file
+ETEXI
+
 DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
     "-serial dev     redirect the serial port to char device 'dev'\n",
     QEMU_ARCH_ALL)
diff --git a/vl.c b/vl.c
index 694deb4..6a30e61 100644
--- a/vl.c
+++ b/vl.c
@@ -490,6 +490,25 @@ static QemuOptsList qemu_semihosting_config_opts = {
     },
 };
 
+static QemuOptsList qemu_fw_cfg_opts = {
+    .name = "fw_cfg",
+    .implied_opt_name = "name",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_fw_cfg_opts.head),
+    .desc = {
+        {
+            .name = "name",
+            .type = QEMU_OPT_STRING,
+            .help = "Sets the fw_cfg name of the blob to be inserted",
+        }, {
+            .name = "file",
+            .type = QEMU_OPT_STRING,
+            .help = "Sets the name of the file from which\n"
+                    "the fw_cfg blob will be loaded",
+        },
+        { /* end of list */ }
+    },
+};
+
 /**
  * Get machine options
  *
@@ -2804,6 +2823,7 @@ int main(int argc, char **argv, char **envp)
     qemu_add_opts(&qemu_numa_opts);
     qemu_add_opts(&qemu_icount_opts);
     qemu_add_opts(&qemu_semihosting_config_opts);
+    qemu_add_opts(&qemu_fw_cfg_opts);
 
     runstate_init();
 
@@ -3420,6 +3440,13 @@ int main(int argc, char **argv, char **envp)
                 }
                 do_smbios_option(opts);
                 break;
+            case QEMU_OPTION_fwcfg:
+                opts = qemu_opts_parse(qemu_find_opts("fw_cfg"), optarg, 0);
+                if (opts == NULL) {
+                    exit(1);
+                }
+                fw_cfg_option_add(opts);
+                break;
             case QEMU_OPTION_enable_kvm:
                 olist = qemu_find_opts("machine");
                 qemu_opts_parse(olist, "accel=kvm", 0);
-- 
2.1.0