libxl: don't ignore the return value from xc_cpuid_apply_policy

Also change libxl__cpuid_legacy to propagate the error from
xc_cpuid_apply_policy into callers.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
(cherry picked from commit 34990446ca91d9e201ff17bd4e3f43bfe3ad308e)

libs/light: Propagate libxl__arch_domain_create() return code

Commit 34990446ca91 started to overwrite the `rc` value from
libxl__arch_domain_create(), thus error aren't propagated anymore.

Check `rc` value before doing the next thing.

Fixes: 34990446ca91 ("libxl: don't ignore the return value from xc_cpuid_apply_policy")
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>
Release-acked-by: Henry Wang <Henry.Wang@arm.com>
(cherry picked from commit 8cdfbf95b19c01fbb741c41d5ea5a94f8823964c)

libxl: fix guest kexec - skip cpuid policy

When a domain performs a kexec (soft reset), libxl__build_pre() is
called with the existing domid.  Calling libxl__cpuid_legacy() on the
existing domain fails since the cpuid policy has already been set, and
the guest isn't rebuilt and doesn't kexec.

xc: error: Failed to set d1's policy (err leaf 0xffffffff, subleaf 0xffffffff, msr 0xffffffff) (17 = File exists): Internal error
libxl: error: libxl_cpuid.c:494:libxl__cpuid_legacy: Domain 1:Failed to apply CPUID policy: File exists
libxl: error: libxl_create.c:1641:domcreate_rebuild_done: Domain 1:cannot (re-)build domain: -3
libxl: error: libxl_xshelp.c:201:libxl__xs_read_mandatory: xenstore read failed: `/libxl/1/type': No such file or directory
libxl: warning: libxl_dom.c:49:libxl__domain_type: unable to get domain type for domid=1, assuming HVM

During a soft_reset, skip calling libxl__cpuid_legacy() to avoid the
issue.  Before commit 34990446ca91, the libxl__cpuid_legacy() failure
would have been ignored, so kexec would continue.

Fixes: 34990446ca91 ("libxl: don't ignore the return value from xc_cpuid_apply_policy")
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
(cherry picked from commit 1e454c2b5b1172e0fc7457e411ebaba61db8fc87)

diff --git a/tools/libxl/libxl_cpuid.c b/tools/libxl/libxl_cpuid.c
index 1b7626f7d41cf91b9104f2620803785ade7ec58d..72fc220de84071a45cc2b717c17496e523974e7f 100644 (file)
--- a/tools/libxl/libxl_cpuid.c
+++ b/tools/libxl/libxl_cpuid.c
@@ -432,10 +432,12 @@ int libxl_cpuid_parse_config_xend(libxl_cpuid_policy_list *cpuid,
     return 0;
 }
 
-void libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
-                         libxl_domain_build_info *info)
+int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
+                        libxl_domain_build_info *info)
 {
+    GC_INIT(ctx);
     bool pae = true;
+    int r;
 
     /*
      * For PV guests, PAE is Xen-controlled (it is the 'p' that differentiates
@@ -450,7 +452,13 @@ void libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
     if (info->type == LIBXL_DOMAIN_TYPE_HVM)
         pae = libxl_defbool_val(info->u.hvm.pae);
 
-    xc_cpuid_apply_policy(ctx->xch, domid, restore, NULL, 0, pae, info->cpuid);
+    r = xc_cpuid_apply_policy(ctx->xch, domid, restore, NULL, 0,
+                              pae, info->cpuid);
+    if (r)
+        LOGEVD(ERROR, -r, domid, "Failed to apply CPUID policy");
+
+    GC_FREE;
+    return r ? ERROR_FAIL : 0;
 }
 
 static const char *input_names[2] = { "leaf", "subleaf" };

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index daf3ff0a5577cdf37a0af8b77432d819121a426b..1554bcca1b6adfc33ce164688bb1cba5ab06a1c6 100644 (file)
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -1438,6 +1438,7 @@ int libxl__srm_callout_callback_static_data_done(unsigned int missing,
 
     libxl_domain_config *d_config = dcs->guest_config;
     libxl_domain_build_info *info = &d_config->b_info;
+    int rc = 0;
 
     /*
      * CPUID/MSR information is not present in pre Xen-4.14 streams.
@@ -1447,9 +1448,9 @@ int libxl__srm_callout_callback_static_data_done(unsigned int missing,
      * stream doesn't contain any CPUID data.
      */
     if (missing & XGR_SDD_MISSING_CPUID)
-        libxl__cpuid_legacy(ctx, dcs->guest_domid, true, info);
+        rc = libxl__cpuid_legacy(ctx, dcs->guest_domid, true, info);
 
-    return 0;
+    return rc;
 }
 
 void libxl__srm_callout_callback_restore_results(xen_pfn_t store_mfn,
@@ -2141,6 +2142,8 @@ static int do_domain_soft_reset(libxl_ctx *ctx,
                               aop_console_how);
     cdcs->domid_out = &domid_out;
 
+    state->soft_reset = true;
+
     dom_path = libxl__xs_get_dompath(gc, domid);
     if (!dom_path) {
         LOGD(ERROR, domid, "failed to read domain path");

diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index f8661e90d4f02ebe1dadbf5a15ed6dca48b28d33..e68ba07ee8f00662aee756e20382f0ce9d7aa6de 100644 (file)
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -386,13 +386,15 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
     state->console_port = xc_evtchn_alloc_unbound(ctx->xch, domid, state->console_domid);
 
     rc = libxl__arch_domain_create(gc, d_config, domid);
+    if (rc) goto out;
 
     /* Construct a CPUID policy, but only for brand new domains.  Domains
      * being migrated-in/restored have CPUID handled during the
      * static_data_done() callback. */
-    if (!state->restore)
-        libxl__cpuid_legacy(ctx, domid, false, info);
+    if (!state->restore && !state->soft_reset)
+        rc = libxl__cpuid_legacy(ctx, domid, false, info);
 
+out:
     return rc;
 }
 

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 3bc3bbcf847b1416cd9a8bcff9b8973a03f00db3..2f531174e6ace977866b7b104223659de10b4aba 100644 (file)
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1403,6 +1403,7 @@ typedef struct {
     /* Whether this domain is being migrated/restored, or booting fresh.  Only
      * applicable to the primary domain, not support domains (e.g. stub QEMU). */
     bool restore;
+    bool soft_reset;
 } libxl__domain_build_state;
 
 _hidden void libxl__domain_build_state_init(libxl__domain_build_state *s);
@@ -2056,8 +2057,8 @@ typedef yajl_gen_status (*libxl__gen_json_callback)(yajl_gen hand, void *);
 _hidden char *libxl__object_to_json(libxl_ctx *ctx, const char *type,
                                     libxl__gen_json_callback gen, void *p);
 
-_hidden void libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool retore,
-                                 libxl_domain_build_info *info);
+_hidden int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool retore,
+                                libxl_domain_build_info *info);
 
 /* Calls poll() again - useful to check whether a signaled condition
  * is still true.  Cannot fail.  Returns currently-true revents. */

diff --git a/tools/libxl/libxl_nocpuid.c b/tools/libxl/libxl_nocpuid.c
index f47336565b9882d2f389784a006e9b9694a500c7..0630959e760c636d06db2332088142b030a237f7 100644 (file)
--- a/tools/libxl/libxl_nocpuid.c
+++ b/tools/libxl/libxl_nocpuid.c
@@ -34,9 +34,10 @@ int libxl_cpuid_parse_config_xend(libxl_cpuid_policy_list *cpuid,
     return 0;
 }
 
-void libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
-                         libxl_domain_build_info *info)
+int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
+                        libxl_domain_build_info *info)
 {
+    return 0;
 }
 
 yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,