[XEN PATCH v2 0/2] libxl: Implement QEMU command line probe

[XEN PATCH v2 0/2] libxl: Implement QEMU command line probe

[Anthony PERARD]

Patch series available in this git branch:
https://xenbits.xen.org/git-http/people/aperard/xen-unstable.git br.libxl-qemu-cmdline-probe-v2

v2:
- removed commited patch
- rename "qemu_cmdline" to "qemu_opts" in struct field and func parameters.
- rename "struct libxl__qemu_available_cmd_line" to
  "struct libxl__qemu_available_opts".

Starting with QEMU 9.0, the option "-chroot", that we use for the
"dmrestrict" feature, is removed. We need to find out which to use
between "-chroot" and "-run-with chroot=dir".

Also, "-runas" is deprecated in QEMU 9.1 and will be remove in a future
release, it's replaced with "-run-with user=user".

To find out which command line option we can use, we'll spawn QEMU, and run the
QMP command "query-command-line-options".

Some example of running these patches:
    with qemu-xen (8.0):
        http://logs.test-lab.xenproject.org/osstest/logs/187352/
    with QEMU (upstream, 9.1-rc3):
        http://logs.test-lab.xenproject.org/osstest/logs/187353/

Anthony PERARD (2):
  libxl: Probe QEMU for -run-with chroot=dir and use it
  libxl: Probe QEMU for -run-with user=user and use it

 tools/libs/light/libxl_dm.c       | 90 +++++++++++++++++++++++++------
 tools/libs/light/libxl_internal.h |  6 +++
 2 files changed, 80 insertions(+), 16 deletions(-)

-- 


Anthony Perard | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech

[XEN PATCH v2 1/2] libxl: Probe QEMU for -run-with chroot=dir and use it

[Anthony PERARD]

QEMU 9.0 have removed "-chroot" command line option, which have been
deprecated since QEMU 8.1 in favor of "-run-with chroot=dir".

Look into the result of the QMP command "query-command-line-options"
to find out if "-run-with chroot=dir" is available. Then use it in
place of "-chroot".

Resolves: xen-project/xen#187
Signed-off-by: Anthony PERARD <anthony.perard@vates.tech>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
---

Notes:
    v2:
    - rename "qemu_cmdline" to "qemu_opts" in struct field and func
      parameters.
    - rename "struct libxl__qemu_available_cmd_line" to
      "struct libxl__qemu_available_opts".

 tools/libs/light/libxl_dm.c       | 78 +++++++++++++++++++++++++------
 tools/libs/light/libxl_internal.h |  5 ++
 2 files changed, 69 insertions(+), 14 deletions(-)

diff --git a/tools/libs/light/libxl_dm.c b/tools/libs/light/libxl_dm.c
index 46babfed0b..15b157060f 100644
--- a/tools/libs/light/libxl_dm.c
+++ b/tools/libs/light/libxl_dm.c
@@ -1183,11 +1183,12 @@ static int libxl__pre_open_qmp_socket(libxl__gc *gc, libxl_domid domid,
 }
 
 static int libxl__build_device_model_args_new(libxl__gc *gc,
-                                        const char *dm, int guest_domid,
-                                        const libxl_domain_config *guest_config,
-                                        char ***args, char ***envs,
-                                        const libxl__domain_build_state *state,
-                                        int *dm_state_fd)
+    const char *dm, int guest_domid,
+    const libxl_domain_config *guest_config,
+    char ***args, char ***envs,
+    const libxl__domain_build_state *state,
+    const libxl__qemu_available_opts *qemu_opts,
+    int *dm_state_fd)
 {
     const libxl_domain_create_info *c_info = &guest_config->c_info;
     const libxl_domain_build_info *b_info = &guest_config->b_info;
@@ -1778,8 +1779,13 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
         }
 
         /* Add "-chroot [dir]" to command-line */
-        flexarray_append(dm_args, "-chroot");
-        flexarray_append(dm_args, chroot_dir);
+        if (qemu_opts->have_runwith_chroot) {
+            flexarray_append_pair(dm_args, "-run-with",
+                                  GCSPRINTF("chroot=%s", chroot_dir));
+        } else {
+            flexarray_append(dm_args, "-chroot");
+            flexarray_append(dm_args, chroot_dir);
+        }
     }
 
     if (state->saved_state) {
@@ -2059,11 +2065,12 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
 }
 
 static int libxl__build_device_model_args(libxl__gc *gc,
-                                        const char *dm, int guest_domid,
-                                        const libxl_domain_config *guest_config,
-                                        char ***args, char ***envs,
-                                        const libxl__domain_build_state *state,
-                                        int *dm_state_fd)
+    const char *dm, int guest_domid,
+    const libxl_domain_config *guest_config,
+    char ***args, char ***envs,
+    const libxl__domain_build_state *state,
+    const libxl__qemu_available_opts *qemu_opts,
+    int *dm_state_fd)
 /* dm_state_fd may be NULL iff caller knows we are using stubdom
  * and therefore will be passing a filename rather than a fd. */
 {
@@ -2081,7 +2088,9 @@ static int libxl__build_device_model_args(libxl__gc *gc,
         return libxl__build_device_model_args_new(gc, dm,
                                                   guest_domid, guest_config,
                                                   args, envs,
-                                                  state, dm_state_fd);
+                                                  state,
+                                                  qemu_opts,
+                                                  dm_state_fd);
     default:
         LOGED(ERROR, guest_domid, "unknown device model version %d",
               guest_config->b_info.device_model_version);
@@ -2403,7 +2412,9 @@ void libxl__spawn_stub_dm(libxl__egc *egc, libxl__stub_dm_spawn_state *sdss)
 
     ret = libxl__build_device_model_args(gc, "stubdom-dm", guest_domid,
                                          guest_config, &args, NULL,
-                                         d_state, NULL);
+                                         d_state,
+                                         &sdss->dm.qemu_opts,
+                                         NULL);
     if (ret) {
         ret = ERROR_FAIL;
         goto out;
@@ -3024,6 +3035,7 @@ static void device_model_probe_detached(libxl__egc *egc,
 static void device_model_probe_cmdline(libxl__egc *egc,
     libxl__ev_qmp *qmp, const libxl__json_object *response, int rc)
 {
+    EGC_GC;
     libxl__dm_spawn_state *dmss = CONTAINER_OF(qmp, *dmss, qmp);
 
     if (rc)
@@ -3033,6 +3045,43 @@ static void device_model_probe_cmdline(libxl__egc *egc,
      * query-command-line-options response:
      * [ { 'option': 'str', 'parameters': [{ 'name': 'str', ... }] } ]
      */
+    const libxl__json_object *option;
+    for (int i_option = 0;
+         (option = libxl__json_array_get(response, i_option));
+         i_option++) {
+        const libxl__json_object *o;
+        const char *opt_str;
+
+        o = libxl__json_map_get("option", option, JSON_STRING);
+        if (!o) {
+            rc = ERROR_QEMU_API;
+            goto out;
+        }
+        opt_str = libxl__json_object_get_string(o);
+
+        if (!strcmp("run-with", opt_str)) {
+            const libxl__json_object *params;
+            const libxl__json_object *item;
+
+            params = libxl__json_map_get("parameters", option, JSON_ARRAY);
+            for (int i = 0; (item = libxl__json_array_get(params, i)); i++) {
+                o = libxl__json_map_get("name", item, JSON_STRING);
+                if (!o) {
+                    rc = ERROR_QEMU_API;
+                    goto out;
+                }
+                if (!strcmp("chroot", libxl__json_object_get_string(o))) {
+                    dmss->qemu_opts.have_runwith_chroot = true;
+                }
+            }
+
+            /*
+             * No need to parse more options, we are only interested with
+             * -run-with at the moment.
+             */
+            break;
+        }
+    }
 
     qmp->callback = device_model_probe_quit;
     rc = libxl__ev_qmp_send(egc, qmp, "quit", NULL);
@@ -3113,6 +3162,7 @@ static void device_model_launch(libxl__egc *egc,
 
     rc = libxl__build_device_model_args(gc, dm, domid, guest_config,
                                           &args, &envs, state,
+                                          &dmss->qemu_opts,
                                           &dm_state_fd);
     if (rc)
         goto out;
diff --git a/tools/libs/light/libxl_internal.h b/tools/libs/light/libxl_internal.h
index e99adc56cb..0133c57e01 100644
--- a/tools/libs/light/libxl_internal.h
+++ b/tools/libs/light/libxl_internal.h
@@ -4142,6 +4142,10 @@ _hidden void libxl__add_nics(libxl__egc *egc, libxl__ao *ao, uint32_t domid,
 /* First layer; wraps libxl__spawn_spawn. */
 
 typedef struct libxl__dm_spawn_state libxl__dm_spawn_state;
+typedef struct libxl__qemu_available_opts libxl__qemu_available_opts;
+struct libxl__qemu_available_opts {
+    bool have_runwith_chroot;
+};
 
 typedef void libxl__dm_spawn_cb(libxl__egc *egc, libxl__dm_spawn_state*,
                                 int rc /* if !0, error was logged */);
@@ -4154,6 +4158,7 @@ struct libxl__dm_spawn_state {
     libxl__ev_qmp qmp;
     libxl__ev_time timeout;
     libxl__dm_resume_state dmrs;
+    libxl__qemu_available_opts qemu_opts;
     const char *dm;
     /* filled in by user, must remain valid: */
     uint32_t guest_domid; /* domain being served */
-- 


Anthony Perard | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech

[XEN PATCH v2 2/2] libxl: Probe QEMU for -run-with user=user and use it

[Anthony PERARD]

"-runas" is deprecated since QEMU 9.1 and will be remove in a future
release.

Signed-off-by: Anthony PERARD <anthony.perard@vates.tech>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
---

Notes:
    v2:
    - rename "qemu_cmdline" to "qemu_opts" in struct field and func
      parameters.

 tools/libs/light/libxl_dm.c       | 12 ++++++++++--
 tools/libs/light/libxl_internal.h |  1 +
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/tools/libs/light/libxl_dm.c b/tools/libs/light/libxl_dm.c
index 15b157060f..1f2f5bd97a 100644
--- a/tools/libs/light/libxl_dm.c
+++ b/tools/libs/light/libxl_dm.c
@@ -2052,8 +2052,13 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
         }
 
         if (state->dm_runas) {
-            flexarray_append(dm_args, "-runas");
-            flexarray_append(dm_args, state->dm_runas);
+            if (qemu_opts->have_runwith_user) {
+                flexarray_append_pair(dm_args, "-run-with",
+                                      GCSPRINTF("user=%s", state->dm_runas));
+            } else {
+                flexarray_append(dm_args, "-runas");
+                flexarray_append(dm_args, state->dm_runas);
+            }
         }
     }
     flexarray_append(dm_args, NULL);
@@ -3073,6 +3078,9 @@ static void device_model_probe_cmdline(libxl__egc *egc,
                 if (!strcmp("chroot", libxl__json_object_get_string(o))) {
                     dmss->qemu_opts.have_runwith_chroot = true;
                 }
+                else if (!strcmp("user", libxl__json_object_get_string(o))) {
+                    dmss->qemu_opts.have_runwith_user = true;
+                }
             }
 
             /*
diff --git a/tools/libs/light/libxl_internal.h b/tools/libs/light/libxl_internal.h
index 0133c57e01..089a2f949c 100644
--- a/tools/libs/light/libxl_internal.h
+++ b/tools/libs/light/libxl_internal.h
@@ -4145,6 +4145,7 @@ typedef struct libxl__dm_spawn_state libxl__dm_spawn_state;
 typedef struct libxl__qemu_available_opts libxl__qemu_available_opts;
 struct libxl__qemu_available_opts {
     bool have_runwith_chroot;
+    bool have_runwith_user;
 };
 
 typedef void libxl__dm_spawn_cb(libxl__egc *egc, libxl__dm_spawn_state*,
-- 


Anthony Perard | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech

Re: [XEN PATCH v2 0/2] libxl: Implement QEMU command line probe

[Andrew Cooper]

On 30/08/2024 10:49 am, Anthony PERARD wrote:
> Patch series available in this git branch:
> https://xenbits.xen.org/git-http/people/aperard/xen-unstable.git br.libxl-qemu-cmdline-probe-v2
>
> v2:
> - removed commited patch
> - rename "qemu_cmdline" to "qemu_opts" in struct field and func parameters.
> - rename "struct libxl__qemu_available_cmd_line" to
>   "struct libxl__qemu_available_opts".
>
> Starting with QEMU 9.0, the option "-chroot", that we use for the
> "dmrestrict" feature, is removed. We need to find out which to use
> between "-chroot" and "-run-with chroot=dir".
>
> Also, "-runas" is deprecated in QEMU 9.1 and will be remove in a future
> release, it's replaced with "-run-with user=user".
>
> To find out which command line option we can use, we'll spawn QEMU, and run the
> QMP command "query-command-line-options".
>
> Some example of running these patches:
>     with qemu-xen (8.0):
>         http://logs.test-lab.xenproject.org/osstest/logs/187352/
>     with QEMU (upstream, 9.1-rc3):
>         http://logs.test-lab.xenproject.org/osstest/logs/187353/
>
> Anthony PERARD (2):
>   libxl: Probe QEMU for -run-with chroot=dir and use it
>   libxl: Probe QEMU for -run-with user=user and use it
>
>  tools/libs/light/libxl_dm.c       | 90 +++++++++++++++++++++++++------
>  tools/libs/light/libxl_internal.h |  6 +++
>  2 files changed, 80 insertions(+), 16 deletions(-)

I've committed these as they're fully reviewed, but I think this
warrants a CHANGELOG.md update as we're fixing libxl to work with newer
QEMU.

~Andrew