virsh: Add iothreadpin command

https://bugzilla.redhat.com/show_bug.cgi?id=1135491

$ virsh iothread --help

  NAME
    iothreadpin - control domain IOThread affinity

  SYNOPSIS
    iothreadpin <domain> <iothread> <cpulist> [--config] [--live] [--current]

  DESCRIPTION
    Pin domain IOThreads to host physical CPUs.

  OPTIONS
    [--domain] <string>  domain name, id or uuid
    [--iothread] <number>  IOThread ID number
    [--cpulist] <string>  host cpu number(s) to set
    --config         affect next boot
    --live           affect running domain
    --current        affect current domain

Using the output from iothreadsinfo, allow changing the pinned CPUs for
a single IOThread.

$ virsh iothreadsinfo $dom
 IOThread ID    CPU Affinity
---------------------------------------------------
 1               2
 2               3
 3               0-1

$ virsh iothreadpin $dom 3 0-2

Then view the change

$ virsh iothreadsinfo $dom
 IOThread ID    CPU Affinity
---------------------------------------------------
 1               2
 2               3
 3               0-2

If an invalid value is supplied or require option missing,
then an error will be displayed:

$ virsh iothreadpin $dom 4 3
error: invalid argument: iothread value out of range 4 > 3

$ virsh iothreadpin $dom 3
error: command 'iothreadpin' requires <cpulist> option

tools/virsh-domain.c

@@ -6877,6 +6877,106 @@ cmdIOThreadsInfo(vshControl *ctl, const vshCmd *cmd)
     return niothreads >= 0;
 }
 
+/*
+ * "iothreadpin" command
+ */
+static const vshCmdInfo info_iothreadpin[] = {
+    {.name = "help",
+     .data = N_("control domain IOThread affinity")
+    },
+    {.name = "desc",
+     .data = N_("Pin domain IOThreads to host physical CPUs.")
+    },
+    {.name = NULL}
+};
+
+static const vshCmdOptDef opts_iothreadpin[] = {
+    {.name = "domain",
+     .type = VSH_OT_DATA,
+     .flags = VSH_OFLAG_REQ,
+     .help = N_("domain name, id or uuid")
+    },
+    {.name = "iothread",
+     .type = VSH_OT_INT,
+     .flags = VSH_OFLAG_REQ,
+     .help = N_("IOThread ID number")
+    },
+    {.name = "cpulist",
+     .type = VSH_OT_DATA,
+     .flags = VSH_OFLAG_REQ,
+     .help = N_("host cpu number(s) to set")
+    },
+    {.name = "config",
+     .type = VSH_OT_BOOL,
+     .help = N_("affect next boot")
+    },
+    {.name = "live",
+     .type = VSH_OT_BOOL,
+     .help = N_("affect running domain")
+    },
+    {.name = "current",
+     .type = VSH_OT_BOOL,
+     .help = N_("affect current domain")
+    },
+    {.name = NULL}
+};
+
+static bool
+cmdIOThreadPin(vshControl *ctl, const vshCmd *cmd)
+{
+    virDomainPtr dom;
+    const char *cpulist = NULL;
+    bool config = vshCommandOptBool(cmd, "config");
+    bool live = vshCommandOptBool(cmd, "live");
+    bool current = vshCommandOptBool(cmd, "current");
+    unsigned int iothread_id = 0;
+    int maxcpu;
+    bool ret = false;
+    unsigned char *cpumap = NULL;
+    size_t cpumaplen;
+    unsigned int flags = VIR_DOMAIN_AFFECT_CURRENT;
+
+    VSH_EXCLUSIVE_OPTIONS_VAR(current, live);
+    VSH_EXCLUSIVE_OPTIONS_VAR(current, config);
+
+    if (config)
+        flags |= VIR_DOMAIN_AFFECT_CONFIG;
+    if (live)
+        flags |= VIR_DOMAIN_AFFECT_LIVE;
+
+    if (!(dom = vshCommandOptDomain(ctl, cmd, NULL)))
+        return false;
+
+    if (vshCommandOptUInt(cmd, "iothread", &iothread_id) < 0) {
+        vshError(ctl, "%s", _("iothreadpin: Invalid IOThread number."));
+        goto cleanup;
+    }
+
+    if (vshCommandOptString(cmd, "cpulist", &cpulist) < 0) {
+        vshError(ctl, "%s", _("iothreadpin: invalid cpulist."));
+        goto cleanup;
+    }
+
+    if ((maxcpu = vshNodeGetCPUCount(ctl->conn)) < 0)
+        goto cleanup;
+    cpumaplen = VIR_CPU_MAPLEN(maxcpu);
+
+    /* Pin mode: pinning specified vcpu to specified physical cpus*/
+    if (!(cpumap = vshParseCPUList(ctl, cpulist, maxcpu, cpumaplen)))
+        goto cleanup;
+
+    if (virDomainPinIOThread(dom, iothread_id,
+                             cpumap, cpumaplen, flags) != 0)
+        goto cleanup;
+
+    ret = true;
+
+ cleanup:
+    VIR_FREE(cpumap);
+    virDomainFree(dom);
+    return ret;
+}
+
 /*
  * "cpu-compare" command
  */
@@ -12786,6 +12886,12 @@ const vshCmdDef domManagementCmds[] = {
      .info = info_iothreads,
      .flags = 0
     },
+    {.name = "iothreadpin",
+     .handler = cmdIOThreadPin,
+     .opts = opts_iothreadpin,
+     .info = info_iothreadpin,
+     .flags = 0
+    },
     {.name = "send-key",
      .handler = cmdSendKey,
      .opts = opts_send_key,

tools/virsh.pod

@@ -1374,6 +1374,32 @@ a persistent guest.
 If I<--current> is specified or I<--live> and I<--config> are not specified,
 then get the IOThread data based on the current guest state.
 
+=item B<iothreadpin> I<domain> I<iothread> I<cpulist>
+[[I<--live>] [I<--config>] | [I<--current>]]
+
+Change the pinning of a domain IOThread to host physical CPUs. In order
+to retrieve a list of all IOThreads, use B<iothreadsinfo>. To pin an
+I<iothread> specify the I<cpulist> desired for the IOThread ID as listed
+in the B<iothreadsinfo> output.
+
+I<cpulist> is a list of physical CPU numbers. Its syntax is a comma
+separated list and a special markup using '-' and '^' (ex. '0-4', '0-3,^2') can
+also be allowed. The '-' denotes the range and the '^' denotes exclusive.
+If you want to reset iothreadpin setting, that is, to pin an I<iothread>
+to all physical cpus, simply specify 'r' as a I<cpulist>.
+
+If I<--live> is specified, affect a running guest. If the guest is not running,
+an error is returned.
+If I<--config> is specified, affect the next boot of a persistent guest.
+If I<--current> is specified or I<--live> and I<--config> are not specified,
+affect the current guest state.
+Both I<--live> and I<--config> flags may be given if I<cpulist> is present,
+but I<--current> is exclusive.
+If no flag is specified, behavior is different depending on hypervisor.
+
+B<Note>: The expression is sequentially evaluated, so "0-15,^8" is
+identical to "9-14,0-7,15" but not identical to "^8,0-15".
+
 =item B<managedsave> I<domain> [I<--bypass-cache>]
 [{I<--running> | I<--paused>}] [I<--verbose>]