[PATCH 06/15] xl: implement and enable dryrun mode for `xl vcpu-pin'

[Dario Faggioli <dario.faggioli@citrix.com>]

As it can be useful to see if the outcome of some complex vCPU
pinning bitmap specification looks as expected.

This also allow for the introduction of some automatic testing
and verification for the bitmap parsing code, as it happens
already in check-xl-disk-parse and check-xl-vif-parse.

In particular, to make the above possible, this commit also
changes the implementation of the vcpu-pin command so that,
instead of always returning 0, it returns an error if the
parsing fails.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
---
Picking this up from a previously submitted series ("xl:
allow for node-wise specification of vcpu pinning") as the
changes in that and in this series would otherwise be
conflicting. If this is considered fine, Feel free to apply
it from here and skip the corresponding e-mail in the
original submission.
---
Changes since v2:
 * fixed a typo in the changelog
---
 tools/libxl/xl_cmdimpl.c  |   49 +++++++++++++++++++++++++++++++++------------
 tools/libxl/xl_cmdtable.c |    2 +-
 2 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 5ece4af..33c0d0d 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -4532,30 +4532,53 @@ int main_vcpulist(int argc, char **argv)
     return 0;
 }
 
-static void vcpupin(uint32_t domid, const char *vcpu, char *cpu)
+static int vcpupin(uint32_t domid, const char *vcpu, char *cpu)
 {
     libxl_vcpuinfo *vcpuinfo;
     libxl_bitmap cpumap;
 
     uint32_t vcpuid;
     char *endptr;
-    int i, nb_vcpu;
+    int i = 0, nb_vcpu, rc = -1;
+
+    libxl_bitmap_init(&cpumap);
 
     vcpuid = strtoul(vcpu, &endptr, 10);
     if (vcpu == endptr) {
         if (strcmp(vcpu, "all")) {
             fprintf(stderr, "Error: Invalid argument.\n");
-            return;
+            goto out;
         }
         vcpuid = -1;
     }
 
-    if (libxl_cpu_bitmap_alloc(ctx, &cpumap, 0)) {
-        goto vcpupin_out;
-    }
+    if (libxl_cpu_bitmap_alloc(ctx, &cpumap, 0))
+        goto out;
 
     if (vcpupin_parse(cpu, &cpumap))
-        goto vcpupin_out1;
+        goto out;
+
+    if (dryrun_only) {
+        libxl_cputopology *info = libxl_get_cpu_topology(ctx, &i);
+
+        if (!info) {
+            fprintf(stderr, "libxl_get_cpu_topology failed.\n");
+            goto out;
+        }
+        libxl_cputopology_list_free(info, i);
+
+        fprintf(stdout, "cpumap: ");
+        print_cpumap(cpumap.map, i, stdout);
+        fprintf(stdout, "\n");
+
+        if (ferror(stdout) || fflush(stdout)) {
+            perror("stdout");
+            exit(-1);
+        }
+
+        rc = 0;
+        goto out;
+    }
 
     if (vcpuid != -1) {
         if (libxl_set_vcpuaffinity(ctx, domid, vcpuid, &cpumap) == -1) {
@@ -4565,7 +4588,7 @@ static void vcpupin(uint32_t domid, const char *vcpu, char *cpu)
     else {
         if (!(vcpuinfo = libxl_list_vcpu(ctx, domid, &nb_vcpu, &i))) {
             fprintf(stderr, "libxl_list_vcpu failed.\n");
-            goto vcpupin_out1;
+            goto out;
         }
         for (i = 0; i < nb_vcpu; i++) {
             if (libxl_set_vcpuaffinity(ctx, domid, vcpuinfo[i].vcpuid,
@@ -4576,10 +4599,11 @@ static void vcpupin(uint32_t domid, const char *vcpu, char *cpu)
         }
         libxl_vcpuinfo_list_free(vcpuinfo, nb_vcpu);
     }
-  vcpupin_out1:
+
+    rc = 0;
+ out:
     libxl_bitmap_dispose(&cpumap);
-  vcpupin_out:
-    ;
+    return rc;
 }
 
 int main_vcpupin(int argc, char **argv)
@@ -4590,8 +4614,7 @@ int main_vcpupin(int argc, char **argv)
         /* No options */
     }
 
-    vcpupin(find_domain(argv[optind]), argv[optind+1] , argv[optind+2]);
-    return 0;
+    return vcpupin(find_domain(argv[optind]), argv[optind+1] , argv[optind+2]);
 }
 
 static void vcpuset(uint32_t domid, const char* nr_vcpus, int check_host)
diff --git a/tools/libxl/xl_cmdtable.c b/tools/libxl/xl_cmdtable.c
index 326a660..d3dcbf0 100644
--- a/tools/libxl/xl_cmdtable.c
+++ b/tools/libxl/xl_cmdtable.c
@@ -211,7 +211,7 @@ struct cmd_spec cmd_table[] = {
       "[Domain, ...]",
     },
     { "vcpu-pin",
-      &main_vcpupin, 0, 1,
+      &main_vcpupin, 1, 1,
       "Set which CPUs a VCPU can use",
       "<Domain> <VCPU|all> <CPUs|all>",
     },