virsh: Fix documentation for memtune command

Commit 78ba748e claims to fix
documentation for swap_hard_limit virsh memtune option but it only fixes
documentation in formatdomain.html and libvirt.h. This patch completes
the task by fixing "virsh help memtune" output and memtune section of
virsh man page.

docs/formatdomain.html.in

@@ -314,7 +314,11 @@
       <dt><code>memtune</code></dt>
       <dd> The optional <code>memtune</code> element provides details
         regarding the memory tunable parameters for the domain. If this is
-        omitted, it defaults to the OS provided defaults.</dd>
+        omitted, it defaults to the OS provided defaults. For QEMU/KVMi, the
+        parameters are applied to the QEMU process as a whole. Thus, when
+        counting them, one needs to add up guest RAM, guest video RAM, and
+        some memory overhead of QEMU itself. The last piece is hard to
+        determine so one needs guess and try.</dd>
       <dt><code>hard_limit</code></dt>
       <dd> The optional <code>hard_limit</code> element is the maximum memory
         the guest can use. The units for this value are kilobytes (i.e. blocks

tools/virsh.c

@@ -3202,7 +3202,7 @@ static const vshCmdOptDef opts_memtune[] = {
     {"soft-limit", VSH_OT_INT, VSH_OFLAG_NONE,
      N_("Memory during contention in kilobytes")},
     {"swap-hard-limit", VSH_OT_INT, VSH_OFLAG_NONE,
-     N_("Max swap in kilobytes")},
+     N_("Max memory plus swap in kilobytes")},
     {"min-guarantee", VSH_OT_INT, VSH_OFLAG_NONE,
      N_("Min guaranteed memory in kilobytes")},
     {NULL, 0, 0, NULL}

tools/virsh.pod

@@ -611,12 +611,42 @@ use the virsh B<edit> command instead to update its XML <memory> element.
 
 =item B<memtune> I<domain-id> optional I<--hard-limit> B<kilobytes>
 optional I<--soft-limit> B<kilobytes> optional I<--swap-hard-limit>
-B<kilobytes> -I<--min-guarantee> B<kilobytes>
+B<kilobytes> optional I<--min-guarantee> B<kilobytes>
 
 Allows you to display or set the domain memory parameters. Without
 flags, the current settings are displayed; with a flag, the
 appropriate limit is adjusted if supported by the hypervisor.  LXC and
-QEMU/KVM supports I<--hard-limit>, I<--soft-limit>, and I<--swap-hard-limit>.
+QEMU/KVM support I<--hard-limit>, I<--soft-limit>, and I<--swap-hard-limit>.
+
+For QEMU/KVM, the parameters are applied to the QEMU process as a whole.
+Thus, when counting them, one needs to add up guest RAM, guest video RAM, and
+some memory overhead of QEMU itself.  The last piece is hard to determine so
+one needs guess and try.
+
+=over 4
+
+=item I<--hard-limit>
+
+The maximum memory the guest can use.  The units for this value are kilobytes
+(i.e. blocks of 1024 bytes).
+
+=item I<--soft-limit>
+
+The memory limit to enforce during memory contention.  The units for this
+value are kilobytes (i.e. blocks of 1024 bytes).
+
+=item I<--swap-hard-limit>
+
+The maximum memory plus swap the guest can use.  The units for this value are
+kilobytes (i.e. blocks of 1024 bytes).  This has to be more than hard-limit
+value provided.
+
+=item I<--min-guarantee>
+
+The guaranteed minimum memory allocation for the guest.  The units for this
+value are kilobytes (i.e. blocks of 1024 bytes).
+
+=back
 
 =item B<blkiotune> I<domain-id> optional I<--weight> B<weight>