[Xen-devel] [PATCH 19/20] tools/libxl: Re-position CPUID handling during domain construction

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

CPUID handling needs to be earlier in construction.  Move it from its current
position in libxl__build_post() to libxl__build_pre() for fresh builds, and
libxl__srm_callout_callback_static_data_done() for the migration/resume case.

In the migration case, take account of XGR_SDD_MISSING_CPUID.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/libxl/libxl_create.c | 19 ++++++++++++++++++-
 tools/libxl/libxl_dom.c    | 12 ++++++++----
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index a8fa4ca11b..0d9a91aeeb 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -1303,8 +1303,25 @@ int 
libxl__srm_callout_callback_static_data_done(unsigned int missing,
     libxl__save_helper_state *shs = user;
     libxl__domain_create_state *dcs = shs->caller_state;
     STATE_AO_GC(dcs->ao);
+    libxl_ctx *ctx = libxl__gc_owner(gc);
+
+    const libxl_domain_config *d_config = dcs->guest_config;
+    const libxl_domain_build_info *info = &d_config->b_info;
 
-    /* TODO - something useful. */
+    /*
+     * For pre-4.14 streams, no CPUID/MSR information will be sent.  Retain
+     * the old behaviour by regenerating CPUID from first principles.
+     */
+    if (missing & XGR_SDD_MISSING_CPUID)
+        libxl_cpuid_apply_policy(ctx, dcs->guest_domid);
+
+    /*
+     * In all cases, cpuid=[] needs re-evaluating.  The common case is that it
+     * will match libxl_cpuid_apply_policy() and/or whatever is in the stream,
+     * but the legacy XEND 'k' modifier passes through host values.
+     */
+    if (info->cpuid != NULL)
+        libxl_cpuid_set(ctx, dcs->guest_domid, info->cpuid);
 
     return 0;
 }
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 01aefa6ce4..099a913019 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -254,6 +254,8 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
     int rc;
     uint64_t size;
 
+    const int restore_fd = dcs->restore_fd;
+
     if (xc_domain_max_vcpus(ctx->xch, domid, info->max_vcpus) != 0) {
         LOG(ERROR, "Couldn't set max vcpu count");
         return ERROR_FAIL;
@@ -376,6 +378,12 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
         return ERROR_FAIL;
     }
 
+    if (restore_fd < 0) {
+        libxl_cpuid_apply_policy(ctx, domid);
+        if (info->cpuid != NULL)
+            libxl_cpuid_set(ctx, domid, info->cpuid);
+    }
+
     xs_domid = xs_read(ctx->xsh, XBT_NULL, "/tool/xenstored/domid", NULL);
     state->store_domid = xs_domid ? atoi(xs_domid) : 0;
     free(xs_domid);
@@ -456,10 +464,6 @@ int libxl__build_post(libxl__gc *gc, uint32_t domid,
     if (rc)
         return rc;
 
-    libxl_cpuid_apply_policy(ctx, domid);
-    if (info->cpuid != NULL)
-        libxl_cpuid_set(ctx, domid, info->cpuid);
-
     if (info->type == LIBXL_DOMAIN_TYPE_HVM
         && !libxl_ms_vm_genid_is_zero(&info->u.hvm.ms_vm_genid)) {
         rc = libxl__ms_vm_genid_set(gc, domid,
-- 
2.11.0


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