[xen stable-4.15] libxl/x86: check return value of SHADOW_OP_SET_ALLOCATION domctl

[patchbot@xxxxxxx]

commit 6bbdcefd205903b2181b3b4fdc9503709ecdb7c4
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Jul 19 12:28:09 2021 +0200
Commit:     Ian Jackson <iwj@xxxxxxxxxxxxxx>
CommitDate: Thu Aug 19 17:46:59 2021 +0100

    libxl/x86: check return value of SHADOW_OP_SET_ALLOCATION domctl
    
    The hypervisor may not have enough memory to satisfy the request. While
    there, make the unit of the value clear by renaming the local variable.
    
    Requested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
    backport-requested-by: Jan Beulich <jbeulich@xxxxxxxx>
    (cherry picked from commit 0be5a00af590c97ea553aadb60f1e0b3af53d8f6)
---
 tools/libs/light/libxl_x86.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/tools/libs/light/libxl_x86.c b/tools/libs/light/libxl_x86.c
index ac09897a63..18c3c77ccd 100644
--- a/tools/libs/light/libxl_x86.c
+++ b/tools/libs/light/libxl_x86.c
@@ -529,10 +529,20 @@ int libxl__arch_domain_create(libxl__gc *gc,
         xc_domain_set_time_offset(ctx->xch, domid, rtc_timeoffset);
 
     if (d_config->b_info.type != LIBXL_DOMAIN_TYPE_PV) {
-        unsigned long shadow = DIV_ROUNDUP(d_config->b_info.shadow_memkb,
-                                           1024);
-        xc_shadow_control(ctx->xch, domid, XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION,
-                          NULL, 0, &shadow, 0, NULL);
+        unsigned long shadow_mb = DIV_ROUNDUP(d_config->b_info.shadow_memkb,
+                                              1024);
+        int r = xc_shadow_control(ctx->xch, domid,
+                                  XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION,
+                                  NULL, 0, &shadow_mb, 0, NULL);
+
+        if (r) {
+            LOGED(ERROR, domid,
+                  "Failed to set %lu MiB %s allocation",
+                  shadow_mb,
+                  libxl_defbool_val(d_config->c_info.hap) ? "HAP" : "shadow");
+            ret = ERROR_FAIL;
+            goto out;
+        }
     }
 
     if (d_config->c_info.type == LIBXL_DOMAIN_TYPE_PV &&
--
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